Analog forecasts

*** Historical breakup probability disclaimer: The 2020 ICEX synoptic pattern is very different than previous years. The result of this is a smaller sample size of comparable events and lower confidence in the relationship between historical conditions and breakup events.

March 24, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a slightly better handle on the synoptic pattern compared to yesterday, but still are struggling with the development of the surface high pressure indicated by all the global models. The transition from low the high pressure in the Chukchi Sea apparently evolves in enough different ways to "confuse" the analogs analysis. That said, the point forecast for SLP at the ICEX camp location mirrors the GFS fairly closely.

At the upper levels, the analogs have a medium handle on the pattern of upper level high pressure over the southwest and a strong upper level low pressure to the north. The pattern of the upper low northwest of Alaska diving southwestward to the Mainland is quite unusual. On the temperature front, the analogs have an excellent handle on the low-level cooling forecast by all the models. Every one of the top analogs has the same trajectory as the GFS output. This gives high confidence in the temperature forecast.

Direct links to files:

• SLP 5-day forecast and SLP Percent analogs animation

• T2M 5-day forecast and T2M Percent analogs animation

• Z500 5-day forecast and Z500 Percent analogs animation

March 23, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have not captured the evolution of the upcoming pattern change very well. The global models all build a ~1036 mb high pressure over the Chukchi Sea by 72 hours. The GFS and CMC keep the core of the high pressure over the Chukchi and drift the center to near the Bering Strait. The ECMWF moves the high pressure directly over the norther Beaufort Sea and then toward Banks island. While this sounds like a divergence of solutions, the GFS and CMC then move the high due eastward from the Bering Strait along the North Slope and then near the Mackenzie River delta by day 6/7. During the day 2-3 period, a low pressure drops from the northeast to a point several hundred miles north of Demarcation Point. All-in-all, the solutions all point to a generally light wind regime after 24 hours.

The analogs did not perform great today. Most of the best matches occurred in the 1940s, 1950s, and 1960s. The SLP analogs did not capture the developing high pressure in the Chukchi Sea. While the analogs do handle the cooling temperatures that the numerical guidance point toward, the large day-to-day changes that appear to be in the forecast are not captured well by the analogs. At the upper levels, the dynamical models call for an upper low to drop southwest from near Banks Island and become established over the Interior. This is a very unusual pattern and as such, the analogs do not capture it. Overall, the analogs are not very useful today.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 22, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a strong handle on the upper level features; e.g., the 500 mb ridge finally moving from west to east along the southern portion of the Mainland. Unlike the upper level pattern, the analogs are a bit messy on the surface features. The global models are now all in agreement on building a massive surface high pressure around 500 miles north or Point Barrow by Day 4-5. The CMC, UKMET, GFS, and ECMWF all agree on this high pressure solution, except the UKMET and ECMWF have the high centered more toward the Chukchi Sea.

The abrupt pattern change from wave after wave of low pressure to a high pressure regime is something that analogs often do not handle well. That said, for the point location of the ICEX camp, the analogs ensemble of the top 5 matches shows an SLP of 1027 mb at Day 5 while the GFS has a pressure of 1032 mb. The analogs generally capture the pattern of pressure drops through Day 3 and big pressure increases through Day 5. The interpretation of this is that the top analogs have correctly identified the changing pattern, but the top 50 analogs used to make the animations have not.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 21, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a solid handle on the synoptic pattern. For the first time in a number of days, late February 2015 is no longer a top analogs match with the regional SLP field. The top matches are: 4/9/62, 4/7/48, 3/28,2019, 3/21/54, and 3/16/93. All but one of the top matches is for a point in the season after today's date. This indicates the pattern is more representative of a pattern later in the season. Following those five days, there is a marked reduction in winds by 48 hours that lasts through the remaining 5 days. This wind forecast is remarkably consistent with today's 12 UTC GFS – which shows light winds from 48-120 hours.

The analogs forecast for SLP and 500 hPa heights are in remarkable agreement with the dynamical models. The 2-meter temps analogs are pretty muddled. In general, it shows a decreasing temperature trend, but the signal is not overly strong.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 20, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a solid handle on the synoptic pattern. Once again, Feb (27), 2015, was the best analog. An animation of sea level pressures and wind speeds from Feb 24 through Mar 4, 2015 (below left and below right) indicate a strong ridge of high pressure developing over the southwest mainland with occasional areas of low pressure dropping from the high Arctic over the top of the upper ridge into the northern Beaufort Sea and to near Banks island.

The analogs ensemble has a very strong signal for a massive upper level high pressure intensifying and retrograding over the Alaska Peninsula. An upper trough develops north of the Beaufort Sea by 48 hours according to all global dynamic models. There is strong agreement with this scenario according to the historical analogs. As was the case yesterday, there is a strong analogs signal for temperatures to drop throughout the five day forecast period. This is nearly identical to the GFS forecast and the NWS forecast for Deadhorse. Before the temperature drop occurs, strong SW winds with blowing snow is indicated by the analogs and the dynamical forecasts.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 19, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a solid handle on the synoptic pattern. Once again, the analogs have identified February 25-26, 2015, as a high quality match. This date has been a match on nearly every day for the last 10 days. This gives excellent confidence that current pattern evolution was captured well be the Feb 25 analog. Using that analog only, the progression from Day 0 is for low pressure near Wrangel Island to move 500 miles north of Pt. Barrow to north of Banks Island by 48-60 hours. After that, strong high pressure developed over southwestern Alaska with a new low pressure north of Demarcation Point became established. This solution is remarkably similar to today's 12 UTC GFS solution.

Looking at a composite of the winds from the top 5 analogs, we see a fluctuation between moderate southwest winds, followed by a period of lower, variable winds. This is a solution that the global models support. The 2-meter temperature forecast from the analogs and the GFS are nearly exactly the same. The same is true of the upper level (500 mb) forecast. Overall, there is excellent agreement between the numerical guidance and the analogs. This gives confidence that the numerical guidance has high levels of predictability.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 18, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a solid handle on the synoptic pattern. The three animations below show the 5-day forecast for SLP, 2-meter temps, and 500 mb heights. In the case of SLP, there is a very strong signal for higher than normal air pressure over the Mainland (although not as high as a week or two ago) and low pressure over the Chukchi Sea and Beaufort Seas. This is a continuation of the pattern that began late last week. These types of patterns often have a series of 2-4 storms that take a similar track. The last storm is frequently the strongest. In this regime, winds are frequently strong, but subside in subsidence on the west side of the parade of shortwave troughs.

The ares of the globe that is currently experiencing the highest temperature anomalies are the Chukchi and Beaufort Seas. Temperatures of 25°F above normal cover the entire ocean area north of Alaska. The analogs have easily captured this feature and the evolution of temperature anomalies over the next five days. The GFS keeps temps in the 10Fs, while the top five analogs try to drop temps near 0F by Day 5; however, the 50-analog ensemble has a stronger warm signal. At the upper levels, the analogs nicely capture the same pattern as the GFS and ECMWF – a massive upper ridge over the mainland that slightly retrogrades to the west as an upper trough slides over the top and lowers heights to near normal over the ICEX camp.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 15, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs had a reasonable handle on the large-scale features. Looking at a composite of the top SLP analogs (4/5/1989, 3/17/1993, 2/26/2015, 3/22/1954, and 3/29/2019, we can construct a 5-day forecast of expected winds (leftmost animation below). This technique continues to show winds up to 20 mph for the next two days from the southwest before relaxing for two days, and then picking up again on Day 5. Nearly every day for the last week, late February 2015 shows up as an SLP match (rightmost animation on below). If we use that date only and project a 5-day wind forecast, we show that southwest winds hang on for another day before relaxing the following two days. Winds pick up somewhat on Day 3 and then ease up on Day 4. This is broadly similar to what the 12 UTC GFS model run depicts.

Note: the ECMWF and GFS both develop a weak low pressure near the camp at Day 3, but the ECMWF maintains southwest winds at 20-25 mph in the vicinity of the ICEX camp nearly continuously for the next 5 days.

As always, the pattern of high pressure over the Mainland with lower pressures in the Arctic waters are poor matches with previous ICEX years.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 14, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs had a reasonable handle on the large-scale features. The details are murkier though. The GFS has a series of weak features moving through over the next few days. The SLP forecast (above left) shows the GFS pressure values bouncing around. The analogs mean tracks the GFS fairly closely. The GFS and analogs air temperature forecasts track closely for the first few days, but then the analogs drops temps near 0F while the GFS warms up to near 15F. In the upper levels, the GFS and ECMWF continue to indicate anomalously high pressure at 500 mb. Even at Day 4-5, there is a 90% agreement that stron high pressure will be over the Mainland and Arctic waters.

SLP Composite: Looking at the top 5 SLP matches from today's 12 UTC run, three of the matches are the same as yesterday. Extrapolating the winds for the next three days from the five matches, we see a core of moderate to strong winds continuing in the nearshore Arctic waters for the next 48 hours (see animation above).

Wind duration: yesterday and the day before, we noted that the best analog match with the Wrangel Island storm showed 60 hours of string winds at Deadhorse. The composite of the top 5 matches showed about 48 hours. As of this writing, the strong winds at the ICEX camp are continuing.

As always, the pattern of high pressure over the Mainland with lower pressures in the Arctic waters are poor matches with previous ICEX years.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 13, 2020 Analogs Forecast:

The storm has arrived. Strong southwesterly winds were observed at the camp before the wind instrument stopped reporting. At Deadhorse, southwest winds sustained at 30-40 mph have been occurring for 24 hours. As noted yesterday, the excellent surface and upper level analogs match from Feb 25, 2015, had strong southwest winds for Deadhorse for nearly 60 hours. The March 26, 1996, and March 10, 1989, events saw strong winds at Deadhorse for only 24 hours. Using a composite of the top analogs matches, winds in the vicinity of the camp stayed in the 20+ knots range for at least 48 hours on average (see rightmost animation below). In all cases, high pressure remained strong enough over the mainland to generate an elevated baseline of westerly winds – even when SLP north of Point Barrow wasn't especially low. That said, the SLP analog forecast does not capture the same mini-high pressure that the global models suggest will switch the winds to southeast after Day 4.

The analogs have a great handle of the upper level high pressure currently anchored over the Mainland. The analogs have shown this feature to be fairly persistent, while dynamical models have shown it to be progressive. Today, the dynamical models have toned-down the progressive nature of the upper ridge-trough pattern. Finally, at the surface, the analogs are back in line with the dynamical models on 2-meter temps. Both the analogs and the GFS drop temperatures back down to single digits above zero Fahrenheit by Day 3.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. Once again there is very little correlation between today's conditions and previous breakup events.

March 12, 2020 Analogs Forecast:

As has been the case for the last week, models are locked in on a developing low pressure near Wrangel Island which is forecast to then move northeastward to north of Banks Island. Both the GFS and the ECMWF have nearly identical solutions (982 vs 983 mb). As with yesterday, we looked at similar instances of a closed low pressure near Wrangel Island, a large high pressure over the Mainland, and a big upper level high pressure over the southern Mainland. A handful of decent matches were identified. Notably, the March 26, 1996, and February 25, 2015, events were good matches for the initial conditions and the synoptic progression. Even though the March 1996 event had a better statistical match score, the February 2015 storm captured the track and pressure fields the following few days much better.

The February 25-27, 2015, event is therefore the best analog in the previous 15 years. At Deadhorse, the winds were sustained from the southwest at 20-35 mph for 60 hours and the temperature was just below freezing for much of that time.

March 11, 2020 Analogs Forecast:

The big news of the day is the developing 982 mb low pressure west of Wrangel Island and the 1059 mb high pressure developing over the eastern Interior at hour 48 (Friday at 12 UTC). Since analogs do not capture these features well using a forecast-scale domain, I expanded the area and looked for similar instances of a deep low pressure near Wrangel Island and strong high pressure over the eastern Interior and western Yukon. The top 20 matches for SLP at 48 hours (when the models show the low pressure fully closed off) and the top 20 matches for the 500 mb height field at 72 hours are shown in the table below. Note that there are several common dates in the group.

A composite of the 5 best SLP matches and tracing following the winds over the next two days, we see that a core of strong southwesterly winds occurred all along the North Slope and offshore waters, with the peak values just to the west and south of the camp location. The first map below shows the Day 1 composite wind speed from the top 5 SLP analogs. At the camp location, strong southwesterly winds around 12 m/s (23 knots). By Day 2, a notable core of strong winds (10 m/s) is evident right along the entire North Slope coast, but not extending very far inland (second image below. My interpretation of these maps is that historically, these synoptic patterns generate strong southwesterly winds in the vicinity of the ICEX camp.

March 10, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs were adjusted somewhat to look at a bigger regional picture. As we have discussed for the last 5 or so days, a storm will be forming near Wrangel Island and will travel northeast from that position to a point about 500 kilometers north of Point Barrow. The latest runs of the GFS and ECMWF both show a 981-982 mb low developing west of Wrangel Island. Successive model runs have trended a little weaker with the low but a little stronger with the high pressure over the mainland. The sensible effect of this pattern is strong southerly winds and warmer temperatures. For the camp location, the analogs analysis does a good job at capturing local pressure changes (see leftmost image below). Unfortunately it does not capture the unusual strength of the low pressure to the north or the unusual strength of the high pressure to the south. A feature of outlier events is that the analogs struggle to find a sufficiently large number of matches. The strength and track of the unusual low pressure means a strong push of southerly (warm) winds is likely. The analogs do not capture this detail.

The global models all develop a massive 575 dm high pressure centered over Kodiak Island and extended over much of Mainland Alaska. There is excellent agreement in the models. For some upper air stations, this will challenge monthly 500 mb height records. The analogs now have a strong handle on the strength and progression of this massive feature (see animation below). While the models are progressive with slowly moving the high pressure into the Yukon/British Columbia region, the analogs has the feature anchored over the Mainland. A feature this winter has been the very strong polar vortex. This feature has locked the pattern in place since mid-December. It appears that this developing storm may be the first domino to drop in the breakdown of the polar vortex

Once again, analogs perform poorly when anomalous events are developing. The developing low pressure is an outlier event. The massive high pressure developing to the south is unusually strong, but a relatively common event and the analogs have a strong handle on it.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. Once again there is very little correlation between today's conditions and previous breakup events.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 9, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs broadly capture the big picture over the mainland and nearshore waters the next few days, but as has been noted before, analogs are particularly bad at capturing outlier events. The GFS is calling for a 976 mb low to form near Wrangel Island at 96 hours. The ECMWF has it at 980 mb near the same location at the same time. Both models are also calling for a 1050+ mb high pressure over the eastern Interior. When the analogs search window is shifted west, it does capture the lower pressure pattern in the same location as the numerical models – but the forecast utility over the ICEX camp location drops with the much larger search box.

At the upper levels, all the global models develop a very impressive ridge across the Gulf of Alaska and southern Mainland – as high as 575 dm in the southern Mainland. The models drift this upper high eastward on days 3-5. No matter where the analogs search window is situated, it always wants to keep the high pressure from moving zonally. This highlights the unusual nature of the local pattern. The NWS is indicating that this pattern may be the beginning of the breakdown of the stratospheric Polar Vortex and our 3-month cold period.

In short, the analogs perform poorly when anomalous events are developing. Take today's reading with caution.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. Once again there is very little correlation between today's conditions and previous breakup events.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 8, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs continue to have a good handle on the SLP trend near the ICEX camp. The GFS and analogs mean are in lock step with one another (see leftmost graphic below). Over the mainland, both the GFS and ECMWF now build a 1050+ mb high over the eastern Interior with 1030+ mb pressure all the way to the west coast. The analogs are less bullish regarding the pressure anomalies. The analogs, by their very nature, have a difficult time capturing outlier events; as such, they do not pick up on the possible Chukchi Sea low pressure. The 2-meter temps in the analogs and the GFS are also in lock step with each other. By Day 5, the GFS shows a 30F temp rise due to the Chukchi Sea storm advecting warmer air northward. As noted earlier, outlier events are not the strong suit of analogs. In the upper levels, the height fields of the GFS, ECMWF, and the analogs are in good agreement (see middle plot below). The developing mega ridge over the Bering Sea is captured by the analogs and the large-scale ridge/trough pattern is effectively shown. On the wind front, there is major disagreement between the analogs and the GFS for the zonal wind component (rightmost plot below).

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. Once again there is very little correlation between today's conditions and previous breakup events. Please note that the program uses a 3-day running mean of conditions to estimate historical matches.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 7, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have a much better handle on the sea level pressure features north of the Alaska coast today. They show the areas of low pressure diving from NW to SE across the Beaufort Sea. The "SLP 5-day forecast" link below shows the nice agreement between the models. In addition, the building high pressure (1040 mb) over the mainland (according to the GFS) on days 3-5 shows up as a very high likelihood of above average pressures at Day 4-5 in the analogs (very high for the time period). On the temperature front, the analogs had been much warmer the previous two days but now are about 10F colder throughout the period. The GFS is now about 10F warmer than the last few days and the two models are now only a few degrees apart throughout the 5-day forecast period. The dividing line between warmer air to the north and colder air to the south is rather sharp. At the upper levels, the individual analogs show a lot of variability, but the analogs mean closely resembles the GFS and the ECMWF with a deep upper low developing over the Chukchi Sea and a huge high pressure over the southern mainland and Gulf of Alaska by Days 4-5.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. With a better handle on the pressure pattern, the previously identified weak correlations with some breakup dates in 2014 have almost completely gone away.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 6, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs have captured the dominant pressure pattern both north and south of the ICEX camp. South of the Interior, it is not capturing the Gulf of Alaska low pressure. Still the broadly low pressure regime north of the ICEX camp with higher pressures to the south continue in both the GFS and the analogs. Weak low pressures that cut off in the Beaufort Sea, as shown in the GFS, are hard for the analogs to resolve – as they are best at handling large-scale patterns. The analogs showed a ~10F to 15F jump in 2-meter temps on yesterday's run and that continues today. There is now a consistent 15F difference between the warmer analogs and the colder GFS throughout the 5-day period. At the upper levels, the cold upper level low pressure is no longer centered over the camp. The GFS and analogs both show a similar trough/ridge pattern, but the analogs has it displayed 200-300 km farther north. This is largely why the 2-meter temps are warmer in the analogs. Throughout the next 5-days, the u-wind (zonal) analysis shows increasing westerly winds over the next five days (good agreement with the GFS). Winds do not appear overly strong though.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions. The continued low correlations with significant breakup events in previous years should be viewed with caution. Today's SLP initialization has a modest (10%ile) match with March 24 & 25, 2014.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 5, 2020 Analogs Forecast:

Using estimated coordinate 71.1N 142.6W, the 12UTC analogs and the GFS both show a sharp SLP drop over the next two days. The GFS keeps the pressure field low with a 1007 mb low pressure, while the analogs do not capture this fairly small feature. The analogs and the GFS both show the forecasted mainland high pressure as a little weaker than previously indicated in the prior few days' runs. Unlike the last few days, the analogs are significantly more bullish on a warming trend building over the Chukchi Sea and moving toward the Beaufort Sea. It shows temperatures peaking near 0°F by Day 2 (48 hours) before dropping back to -10°F by Day 5. Interestingly, the GFS has trended a little colder compared to yesterday. The pattern this entire winter for all the global models has been to forecast too warm and finally catch on the the cooler patter at the last minute. This anecdotal experience favors the GFS over the analogs for 2-meter temps. A new variable added today is the U-wind component. The historical spatial correlation between U-wind and surrounding areas is shown as a tight band from around Wrangel Island to Great Bear Lake, Canada. Links to the U-wind forecasts were added below. The U-wind represents the zonal (east-west) wind component measured in meters per second. Larger values represent stronger westerly (or weaker easterly) winds. Over the 5-day period, the analogs shows a slightly stronger westerly (from the west) wind component by about 2 meters per second.

As previously noted, this year's ICEX camp occurs during a period of atmospheric conditions not typically experienced during prior ICEX missions (although similar to 2007 and 2017). The continued low correlations with significant breakup events in previous years should be viewed with caution.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• U-Wind 5-day forecast U-wind Percent analogs animation

March 2, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. The analogs did not initialize well with the SLP pattern. A series of weak high and low pressures north of Alaska are difficult for analogs to match up with. Starting at 24 hours, the SLP pattern matches very well with the GFS with building a strong area of high pressure over the mainland with weak low pressure north of 75N. The high pressure is forecast to move steadily from west to east over the land mass of North America. The analogs are about a day slower than the GFS with moving the high pressure along to the east. As with the SLP pattern, the analogs did not initialize the deep upper low from the Beaufort to the Gulf of Alaska well. Beyond Day 1, it captures the evolution of the 500 hPa flow in a similar manner as the GFS and ECMWF. The analogs have been excellent in forecasting 2-meter temps. After days of flip-flopping, the GFS finally has a similar forecast as the analogs. For the first time, am beginning to see some 20% matches with breakup events from prior to 2018 at Day 4.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

March 1, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. All five of the top SLP analogs match the GFS forecast for days 1-5. What they are struggling with is the surrounding pressure fields. The GFS has a series of closed lows and highs in the vicinity of the ICEX camp, but the range of pressures is relatively modest. The analogs show a strong signal for strong high pressure developing over the mainland. The GFS also shows a > 1030 hPa high pressure over the mainland. The placement of the highs and lows in the analogs indicates relatively light winds. At the upper levels, the analogs does not capture the low heights over the region on Days 0-3 but shows the trend toward higher heights on days 4-5. The Rossby Wave pattern is well captured. I haven't mentioned the 2-meter temp before, but the GFS has been terrible at initializing the low temps. The analogs have been much better with the temperature regime and forecast.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

February 29, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. We're starting to see some divergence between the analogs and the GFS. The GFS shows a closed high pressure building north of the ICEX camp during the 48 to 96 hour time frame, and low pressure moving toward the camp afterward. The analogs does not capture the GFS's high pressure feature. The high over the mainland is shown farther north than the dynamic models. At the upper levels, the first two days of analogs are in good agreement with all the dynamic models. Afterward, all dynamic models build a upper level low over the entire mainland. The analogs are slow to catch on to the pattern shift. Overall, the analogs did not do well on this run and should be used with caution.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

February 28, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. The analogs forecast continues to show strong high pressure over mainland Alaska. Unlike previous days, the historical analogs suggest the high pressure will drift into the Yukon Territory and then southeast. North of Alaska, the analogs have a weak signal for generally lower pressure. The GFS closes off a weak low pressure just north of the ICEX camp. The analogs SLP pressure pattern favors weak winds throughout the forecast period – west/southwest winds on Days 0-2 but variable afterward. The global models develop a strong low pressure moving into the southern Mainland by Day 4-5. The analogs have not captured this feature – likely because the analysis domain is much farther north. In the upper levels, the analogs generally capture the 500 hPa pressure pattern of a low north and northeast of the Beaufort Sea and a high south and southeast of Alaska; however, the analogs has these features shifted several hundred kilometers northward. None of the forecast variables shows anything more than a 5th percentile match with critical breakup dates prior to 2018.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

February 27, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. The analogs forecast continues to show strong high pressure over mainland Alaska and low pressure due north of Alaska. The trend for the low pressure north of Alaska is slightly weather than yesterday; therefore, the trend yesterday for stronger west and southwest winds is somewhat reduced for today. The analogs more closely resemble the Feb 24-25 analogs for SLP. At the 500 hPa level, the analogs are locking on to higher geopotential heights for mainland Alaska and extending north of the state. This is notably stronger than the GFS, but with the same direction of height changes over the next five days. None of the forecast variables shows anything more than a 10th percentile match with critical breakup dates prior to 2018.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

• February 27, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC. The analogs forecast continues to show strong high pressure over mainland Alaska and low pressure due north of Alaska. The trend for the low pressure north of Alaska is slightly weather than yesterday; therefore, the trend yesterday for stronger west and southwest winds is somewhat reduced for today. The analogs more closely resemble the Feb 24-25 analogs for SLP. At the 500 hPa level, the analogs are locking on to higher geopotential heights for mainland Alaska and extending north of the state. This is notably stronger than the GFS, but with the same direction of height changes over the next five days. None of the forecast variables shows anything more than a 10th percentile match with critical breakup dates prior to 2018.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

February 26, 2020 Analogs Forecast:

Using estimate coordinate 71.2N 142.3W, the 12UTC analogs product generated the following 5-day sea level pressure (SLP) forecast. The red line is the GFS operational mean, the green dashed line is the analogs mean. Each blue line is an analogs member. The animation shows a 5-day forecast plot of the percentage of the top 50 analogs that have an above normal or below normal SLP for the date. The SLP analogs forecast for Days 0-3 show lower pressure north of Alaska than the previous day's runs. It also shows the ridge over the mainland to be slightly farther south than yesterday. This pattern favors stronger winds from the west and southwest than was indicated the previous two days.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation

February 24, 2020 Analogs Forecast:

Using estimate coordinate 71.1N 142.6W, the 12UTC analogs product genrated the following 5-day sea level pressure (SLP) forecast. The red line is the GFS operational mean, the green dashed line is the analogs mean. Each blue line is an analogs member. The animation shows a 5-day forecast plot of the percentage of the top 50 analogs that have an above normal or below normal SLP for the date. On day 0 to 2, a strong majority of analog members favor strengthening high pressure over mainland Alaska with a slow west to east drift. This favors a westerly wind flow in the vicinity of the ICEX camp. None of the next five days is an SLP pattern match for any of the critical match days identified previously.

Direct links to files:

• SLP 5-day forecast SLP Percent analogs animation

• T2M 5-day forecast T2M Percent analogs animation

• Z500 5-day forecast Z500 Percent analogs animation