May 31, 2013

Post date: May 31, 2013 2:11:47 PM

Friday, May 31 @0900 CDT: Yesterday's chase got started quite early, with cells popping up around Oklahoma City early in the afternoon. We got on one north of OKC, and tracked it for quite a while. It had some serious rotation, and it looked like it was going to drop a funnel on numerous occasions (Several chasers reported having seen one.), but we never saw one. Even so, it was a great cell to chase!

I have uploaded a few pictures from the day HERE.

As for today, which looks to be our last actual chase day (since options tomorrow will probably be way out of range for us, given that we all have to get back to Norman, OK for our departing flights on Sunday), we once again have a Moderate Risk. Could the last chase be tornadic? Pretty please???

Oh, and here's yesterday's travel map:

Friday, May 31 @1145 CDT: The SPC has released the 1630z update... Here's the scoop:

Forecast Discussion

SPC AC 311629

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1129 AM CDT FRI MAY 31 2013

VALID 311630Z - 011200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING ACROSS PARTS OF CNTRL OK... SERN KS... AND SWRN MO...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE GREAT PLAINS INTO UPPER MIDWEST...

...REGIONAL SEVERE WEATHER OUTBREAK POSSIBLE TODAY OVER PARTS OF CENTRAL/EASTERN OK...SOUTHEAST KS...AND SOUTHWEST MO. VERY LARGE HAIL...WIDESPREAD DAMAGING WINDS...AND A FEW STRONG TORNADOES/VIOLENT ARE POSSIBLE...

...OK/KS/MO...

ANOTHER VERY VOLATILE ENVIRONMENT IS IN PLACE ACROSS PARTS OF THE SOUTHERN PLAINS AND MID MS VALLEY TODAY. WIDESPREAD VERY STEEP MID LEVEL LAPSE RATES AND DEWPOINTS IN THE UPPER 60S/LOWER 70S ARE RESULTING IN THE POTENTIAL FOR AFTERNOON MLCAPE VALUES OVER 4000 J/KG. THIS AIR MASS IS CURRENTLY CAPPED...AND THE CAP SHOULD RESTRAIN DEEP CONVECTION THROUGH MUCH OF THE DAY ALLOWING STRONG HEATING.

BY MID/LATE AFTERNOON...A SHORTWAVE TROUGH INDICATED IN WATER VAPOR IMAGERY OVER THE TX PANHANDLE...ALONG WITH A SECOND AND STRONGER TROUGH OVER CO...WILL APPROACH THE REGION. THIS WILL RAPIDLY WEAKEN THE CAP AND ALLOW EXPLOSIVE THUNDERSTORM DEVELOPMENT ALONG THE DRYLINE OVER WEST-CENTRAL OK...AND ALONG THE COLD FRONT EXTENDING FROM CENTRAL OK INTO SOUTHWEST MO. DEEP LAYER EFFECTIVE SHEAR VALUES ARE FAVORABLE FOR SUPERCELL STORMS CAPABLE OF VERY LARGE HAIL...DAMAGING WINDS...AND TORNADOES. SHEAR VECTORS PERPENDICULAR TO THE N-S DRYLINE OVER CENTRAL OK WILL FAVOR DISCRETE STORM STRUCTURES. ALL 12Z MODEL GUIDANCE INDICATES RAPID INTENSIFICATION OF THE LOW LEVEL JET OVER CENTRAL OK BY EVENING AS THE UPPER TROUGH APPROACHES. GIVEN THESE PARAMETERS...IT APPEARS THE THREAT OF A FEW STRONG/VIOLENT TORNADOES ARE IN PLACE. HAVE INCREASED SEVERE PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.

DURING THE EVENING...NUMEROUS THUNDERSTORMS ARE EXPECTED TO CONGEAL INTO A FAST-MOVING MCS THAT TRACKS NORTHEASTWARD ACROSS NORTHEAST OK INTO SOUTHWEST KS. HIGH CAPE VALUES AND AN INCREASING LOW LEVEL JET WILL PROMOTE THE POTENTIAL FOR WIDESPREAD WIND DAMAGE...ALONG WITH LARGE HAIL AND ISOLATED TORNADOES.

...IA/MN/WI...

AN UPPER LOW IS PRESENT THIS MORNING OVER WESTERN SD...WITH MULTIPLE SHORTWAVE TROUGHS ROTATING NORTHWARD ACROSS IA/MN. STRONG DAYTIME HEATING IS OCCURRING AHEAD OF THE SHORTWAVE TROUGHS OVER PARTS OF MN/WI/IA WHERE MODERATE AFTERNOON CAPE IS EXPECTED. CATTERED THUNDERSTORMS ARE EXPECTED TO FORM BY MID AFTERNOON OVER MN/IA AND TRACK NORTHEASTWARD. A FEW OF THESE STORMS COULD BE SUPERCELLULAR WITH A RISK OF HAIL/DAMAGING WINDS OR AN ISOLATED TORNADO.

...IL/IND...

AN ONGOING CLUSTER OF THUNDERSTORMS IN THE STL AREA MAY RE-INTENSIFY THIS AFTERNOON AS IT TRACKS INTO AN INCREASINGLY MOIST/UNSTABLE AIR MASS OVER IL/IND. IF THIS OCCURS...LOCALLY DAMAGING WINDS AND HAIL WILL BE POSSIBLE.

..HART/LEITMAN.. 05/31/2013

Friday, May 31 @1530 CDT: The SPC has issued a PDS watch (i.e., Particularly Dangerous Situation) for much of Oklahoma.

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 262

NWS STORM PREDICTION CENTER NORMAN OK

330 PM CDT FRI MAY 31 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF

CENTRAL AND NORTHEAST OKLAHOMA

* EFFECTIVE THIS FRIDAY AFTERNOON FROM 330 PM UNTIL MIDNIGHT CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

* PRIMARY THREATS INCLUDE...

SEVERAL INTENSE TORNADOES LIKELY

NUMEROUS VERY LARGE HAIL EVENTS TO 4 INCHES IN DIAMETER LIKELY

NUMEROUS DAMAGING WIND GUSTS LIKELY WITH SEVERAL SIGNIFICANT

GUSTS TO 80 MPH POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE

MILES EAST AND WEST OF A LINE FROM 20 MILES WEST NORTHWEST OF

BARTLESVILLE OKLAHOMA TO 30 MILES EAST OF WICHITA FALLS TEXAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU2).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 260...WW 261...

DISCUSSION...AN EXTREMELY UNSTABLE AIR MASS HAS DEVELOPED ACROSS

MUCH OF CENTRAL/EASTERN OK THIS AFTERNOON. THIS WILL LIKELY RESULT

IN RAPID DEVELOPMENT OF SEVERE THUNDERSTORMS THIS AFTERNOON AND

EVENING ALONG THE DRYLINE OVER WEST-CENTRAL OK...AND ALONG A WEAK

BOUNDARY EXTENDING NORTHEASTWARD INTO NORTHEAST OK. DISCRETE

SUPERCELLS CAPABLE OF EXTREMELY LARGE HAIL AND DAMAGING TORNADOES

ARE POSSIBLE. DAMAGING WINDS WILL BECOME AN INCREASING THREAT

THROUGH THE EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

600. MEAN STORM MOTION VECTOR 26025.

...HART