27P (Ann) Advisories

...27P close to degenerating...

Center Track Forecast

12 hours: 35 knots; 40 mph; 65 km/h (Open wave)24 hours: 30 knots; 35 mph; 55 km/h (Dissipating, just offshore)

Advisory 3


1-minute sustained wind: 40 knots; 45 mph; 75 km/hEstimated minimum pressure: 1000 mbCurrent position: 14.5S, 149.3E

Public Advisory

Ann has weakened quite considerably since the previous advisory, now on the verge of degenerating into a fast moving, open tropical wave. Ann currently has winds of 40 knots, or 75 kilometers per hour, mostly on its south side, and is moving west-northwestward 13 knots or 24 kilometers per hour.
As Ann is expected to degenerate into an open tropical wave in the next 24 hours, this is the final scheduled advisory on this cyclone. Advisories will resume if determined to be necessary.

Scientific Discussion

Ann's satellite appearance has deteriorated significantly, now with a heavily exposed low-level center due to shear as well as dry air intrusion; it should be noted that Ann's circulation is now almost indistinguishable on water vapor imagery. An ASCAT pass from about 12 hours ago that revealed 40 knot winds on its southwest side suggests winds of 45 knots at the time; given the rate of deterioration in the satellite appearance, the winds are lowered to 40 knots at this time. It should be especially highlighted that winds on the northern side are estimated to be near 5 to 10 knots; by technical definition, Ann is close to becoming an open tropical wave, similar to Caribbean storms such as Beryl and Isaac of 2018.
There is not much left in terms of the forecast for Ann; it is expected to make landfall in the northern Cape York peninsula in about 24 hours as an open tropical wave, mostly following the guidance of the GFS and HWRF. The intensity forecast just follows a statistical decay method for tropical cyclones dissipating into an open wave due to strong wind shear and dry air intrusion, placing it as a tropical depression-equivalent system in terms of winds at landfall in 24 hours.

Forecaster ID

MCK

Advisory Archive

Below is an archive of previous advisories for 94P.

...27P stronger as it approaches Queensland...

Center Track Forecast

12 hours: 50 knots; 60 mph; 95 km/h24 hours: 45 knots; 50 mph; 85 km/h36 hours: 40 knots; 45 mph; 75 km/h48 hours: 35 knots; 40 mph; 65 km/h72 hours: 30 knots; 35 mph; 55 km/h (Dissipating)

Advisory 2


1-minute sustained wind: 55 knots; 65 mph; 100 km/hEstimated minimum pressure: 990 mbCurrent position: 15.3S, 153.9E

Public Advisory

Ann has strengthened in the past 24 hours, now with 1-minute sustained winds of 55 knots, or 100 kilometers per hour, and is moving westward at 12 knots, or 22 kilometers per hour. It is forecasted to make landfall in northern Queensland in approximately 48-54 hours as a low-end tropical storm on the Saffir-Simpson scale, and dissipate over the Gulf of Carpentaria in approximately 72 hours.

Scientific Discussion

Ann, after strengthening to high-end tropical storm status, has seemed to level off in intensity, and seems to be visibly deteriorating after developing an impressive CDO measuring approximately 200 nautical miles wide, though this pattern may have otherwise been indicative of a CCC pattern, in which little development actually occurred-- a CCC pattern like this usually occurs during the diurnal convective maximum, in which Ann is currently transitioning through; furthermore the remaining convection seems focused primarily on the southern half of the cyclone. Position-wise, it is difficult to pinpoint the exact center as it is heavily shrouded. Regardless of this, Ann continues to display characteristics of high-end tropical storm status. Subjective Dvorak estimates are currently at T3.0/45 knots, with one submission at T3.5/55 knots; the ADT is estimating at 63 knots, while SATCON estimates at 58 knots. I am setting the intensity estimate at 55 knots-- at the average of these estimates.
There is some slight change equatorward by way of the forecast reasoning in terms of the track forecast: a subtropical ridge is still expected to provide the primary steering flow for 27P as it continues to move towards Queensland. There are some changes in terms of the intensity forecast-- short-term has been tuned upward as wind shear in 27P's path is decreasing slightly more than predicted yesterday. Regardless, sea surface temperatures along the way are marginally favorable, at 27C, with some pockets of 26C, and mid-level RHs are also expected to be marginally favorable as well, with area-averaged values dipping towards 50%. This forecast generally lies within the middle of the intensity guidance.

Forecaster ID

MCK

...27P continues moving westward...

Center Track Forecast

12 hours: 60 knots; 70 mph; 110 km/h24 hours: 55 knots; 65 mph; 100 km/h36 hours: 45 knots; 50 mph; 85 km/h48 hours: 40 knots; 45 mph; 75 km/h72 hours: 30 knots; 35 mph; 55 km/h96 hours: 15 knots; 15 mph; 30 km/h

Advisory 1


1-minute sustained wind: 45 knots; 50 mph; 85 km/hEstimated minimum pressure: 995 mbCurrent position: 16.4S, 158.8E

Public Advisory

27P continues to move westward as a fairly small tropical cyclone. It should be noted that as a result of its small core, 27P has the capability of having extremely unstable intensity changes. It is currently estimated as having winds of 45 knots or 85 kilometers per hour, and is expected to continue strengthening for the next 24 hours or so. In approximately 60-72 hours, 27P is expected to make landfall in northern Queensland as a weak tropical cyclone.

Scientific Discussion

27P has visibly strengthened quite notably since advisory P-1 approximately 6 hours ago, with Dvorak estimates at T3/45 knots, with some analyses at T3.5/55 knots; the SATCON is estimating 47 knots, and the ADT is estimating at 47 knots as well. An ASCAT pass has captured winds of around 45 knots. For this advisory I will be somewhat conservative and place the 1-minute sustained wind estimate at 45 knots to place more value to the ASCAT passes.
The track forecast is surprisingly straightforward: a subtropical ridge is expected to provide the primary steering pattern for 27P, and will keep it moving westward and somewhat equatorward as the ridge begins to move northward. Model guidance is in a very narrow cluster around 40 nautical miles wide; this advisory stays close to the model consensus. The intensity forecast, however, rides well above the model guidance, given that 27P is maintaining a small core, which could result in very erratic intensity changes.

Forecaster ID

MCK

...94P forms...


Advisory P-1


1-minute sustained wind: 35 knots; 40 mph; 65 km/hEstimated minimum pressure: 1003 mbCurrent position: 16.4N, 159.1E

Public Advisory

Given available data, Invest 94P has coalesced into a tropical storm, with winds of 35 knots, or 65 kilometers per hour. Currently the cyclone is moving westward towards Queensland, at a speed of around 8 knots, or around 15 kilometers per hour. It is expected to intensify for the next 24 hours, though it is expected to weaken as it approaches Queensland.
The first full advisory, including a center track forecast, will be published in approximately 5 hours, or 00Z/April 12.

Scientific Discussion

The available data, including ASCAT passes, Dvorak analysis, and satellite imagery, all strongly suggest that 94P has closed off into a tropical cyclone, with poleward outflow and more organized convection, as well as low-level stratocumulus spinning around a defined low-level circulation. ASCAT passes have missed around half of the storm, with peak winds of around 30 knots detected, and Dvorak estimates ranging from T2.5/35 knots to T3/45 knots; for this advisory I have elected to set the intensity at 35 knots, at the average of these values.

Forecaster ID

MCK