Saturday, March 19, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 192004
SWODY1
SPC AC 192002

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0302 PM CDT SAT MAR 19 2011

VALID 192000Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PART OF THE SRN PLAINS
TO WRN MO AND FAR NWRN AR...

...SLIGHT RISK AREA HAS BEEN EXPANDED EWD ACROSS MORE OF ERN OK/NWRN
AR AND SWRN MO...WITH A SECOND EXTENSION OF THE SLIGHT RISK ACROSS
MORE OF SRN AND CENTRAL KS...

...TX PANHANDLE/NERN OK/ERN KS/WRN MO...
GIVEN RECENT CONVECTIVE TRENDS...WITH TSTMS HAVING DEVELOPED SINCE
18Z PER RADAR IMAGERY FROM NE OF OKC INVOF CQB AND THEN NEWD TO
NOWATA COUNTY OK TO SERN KS...EWD EXPANSION OF SLIGHT IS NEEDED.
THIS ACTIVITY APPEARS TO BE LOCATED ALONG A CONVECTIVE OUTFLOW
BOUNDARY ATTENDANT TO EARLIER CONVECTION WHICH IS CONTINUING TO MOVE
INTO WRN/SWRN MO. THE SEWD MOVEMENT OF THIS BOUNDARY IN CENTRAL OK
IS LIKELY SHUNTING THE NWD PROGRESSION OF THE WARM FRONT...WHILE
FARTHER E...OBJECTIVE ANALYSES INDICATED THIS FRONT HAS MADE
GREATEST NEWD MOVEMENT. THESE TRENDS /BOTH IN RADAR IMAGERY AND
THERMODYNAMICS/ SUGGEST A THREAT FOR SEVERE STORMS MAY OCCUR FARTHER
E THAN PREVIOUSLY FORECAST...AND THUS HAVE EXTENDED THE SLIGHT RISK
AREA/ATTENDANT PROBABILITIES INTO A LITTLE MORE OF ERN OK...NWRN
AR...AND SWRN MO.

...NWRN-NORTH CENTRAL OK INTO PARTS OF SRN/CENTRAL KS...
WATER VAPOR IMAGERY SHOWED A MIDLEVEL IMPULSE TRACKING ENEWD THROUGH
THE CENTRAL/SRN HIGH PLAINS...WHILE ONE AREA OF SURFACE PRESSURE
FALLS WAS CENTERED OVER WRN KS ATTENDANT TO THIS MIDLEVEL FEATURE.
REGIONAL RADAR IMAGERY INDICATED A PERSISTENT SECOND AREA OF TSTMS
MOVING INTO SOUTH CENTRAL KS WITH ACTIVITY ALSO LOCATED INTO
NWRN-NRN OK. THIS ACTIVITY APPEARS TO BE ELEVATED WELL NORTH OF THE
PRIMARY WARM FRONT WHICH IS BISECTING OK SW-NE...AND NNE OF A SECOND
BOUNDARY EXTENDING NWWD FROM CENTRAL TO NWRN OK. ASCENT AHEAD OF
THE HIGH PLAINS TROUGH AND LOW LEVEL WAA N OF THE SECONDARY BOUNDARY
WILL CONTINUE TO SUPPORT THIS AREA OF CONVECTION WITH AN ATTENDANT
THREAT FOR MAINLY HAIL. THUS...HAVE EXPANDED THE SLIGHT RISK AREA
AND HAIL PROBABILITIES ACCORDINGLY.

..PETERS.. 03/19/2011

.PREV DISCUSSION... /ISSUED 1112 AM CDT SAT MAR 19 2011/

BROAD CYCLONIC UPPER FLOW WILL PERSIST OVER THE WESTERN UNITED
STATES TODAY...WHILE A SUBTLE SHORTWAVE TROUGH OVER CO/NM MOVES INTO
THE SOUTHERN PLAINS. THE FOCUS FOR SEVERE THUNDERSTORMS WILL BE
ACROSS PORTIONS OF TX/OK INTO THE MID MS VALLEY.

...OK/KS/MO...
MULTIPLE CLUSTERS OF STRONG TO SEVERE STORMS ARE ONGOING AT THIS
TIME OVER PORTIONS OF NORTHEAST OK AND EASTERN KS. THIS ACTIVITY
INTENSIFIED THIS MORNING AS ASCENT IN ADVANCE OF AN APPROACHING
SHORTWAVE TROUGH OVERSPREAD THE REGION. MORNING RAOBS SHOWS STEEP
MID LEVEL LAPSE RATES...MODERATE ELEVATED CAPE...AND SUFFICIENT
EFFECTIVE SHEAR FOR A FEW ROTATING STORMS CAPABLE OF LARGE HAIL.
THESE STORMS WILL LIKELY PERSIST AS THEY SPREAD EASTWARD INTO MO
THIS AFTERNOON. HOWEVER...THE EXTENT OF SEVERE THREAT FARTHER EAST
IS IN QUESTION AS CONVECTION MOVES INTO A MORE STABLE ENVIRONMENT.
NEVERTHELESS HAVE ADJUSTED SLIGHT RISK A LITTLE FARTHER EAST.

ANOTHER AREA OF CONVECTION IS OVER WESTERN OK AND IS IN CLOSER
PROXIMITY TO APPROACHING UPPER TROUGH. SO FAR...THESE STORMS HAVE
BEEN IN A DRIER/MORE STABLE AIR MASS. HOWEVER...INTENSIFICATION IS
EXPECTED BY EARLY AFTERNOON AS STORMS SPREAD ACROSS NORTHERN OK.
LARGE HAIL WILL BE THE MAIN THREAT WITH THESE STORMS AS WELL.

...OK/TX LATE THIS AFTERNOON AND EVENING...
SEVERAL MODEL SOLUTIONS ARE SUGGESTING THE POTENTIAL FOR ISOLATED
THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON AND EVENING OVER
SOUTHWEST OK AND WEST TX. THE HIGHEST PROBABILITY OF INITIATION
APPEARS TO BE IN OK...WITH THE POTENTIAL OF STORMS DECREASING
FARTHER SOUTH. IF A STORM CAN FORM IN THIS ENVIRONMENT...SUPERCELL
STRUCTURES WOULD BE LIKELY WITH LARGE HAIL AND DAMAGING WINDS
POSSIBLE. EVEN A TORNADO COULD OCCUR MAINLY OVER SOUTHWEST OK WHERE
FORECAST SOUNDINGS SHOW SUFFICIENT LOW LEVEL AND DEEP LAYER VERTICAL
SHEAR.

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