SWODY3
SPC AC 170729
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT MON MAY 17 2010
VALID 191200Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND
CNTRL PLAINS...
...SRN AND CNTRL PLAINS...
A NEGATIVELY-TILTED UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE
HIGH PLAINS WEDNESDAY AS A WELL-DEVELOPED LOW-LEVEL JET STRENGTHENS
ACROSS THE SRN AND CNTRL PLAINS. ELEVATED THUNDERSTORMS MAY BE
ONGOING ALONG THE LOW-LEVEL JET AXIS IN THE SRN PLAINS WEDNESDAY
MORNING. IN RESPONSE TO THE LOW-LEVEL JET...MOISTURE SHOULD RETURN
QUICKLY NWD INTO NORTH TX AND OK. THIS SHOULD RESULT IN A BROAD
CORRIDOR OF MODERATE TO STRONG INSTABILITY ACROSS THE SLIGHT RISK
ESPECIALLY IN AREAS WHERE CONVECTION CLEARS DURING THE LATE MORNING.
IN ADDITION...DEEP LAYER SHEAR SHOULD INCREASE DURING THE DAY ACROSS
THE SRN PLAINS AS A MID-LEVEL JET IN THE BASE OF THE UPPER-LEVEL
TROUGH MOVES INTO THE REGION.
ETA-KF FORECAST SOUNDINGS ACROSS OK AND NORTH TX ARE QUITE
IMPRESSIVE WEDNESDAY AFTERNOON SHOWING 40 TO 50 KT OF DEEP LAYER
SHEAR WITH SFC DEWPOINTS IN THE UPPER 60S F AND MLCAPE VALUES AROUND
3000 J/KG. THIS COMBINED WITH STEEP MID-LEVEL LAPSE RATES SHOULD
EASILY SUPPORT SUPERCELLS WITH VERY LARGE HAIL POSSIBLE WITH THE
MORE INTENSE CORES. IN ADDITION...THE NAM AND GFS ARE IN RELATIVELY
GOOD AGREEMENT CONCERNING THE POSITION OF A 35 TO 45 KT JET MAX NEAR
850 MB IN CNTRL OK. THIS JET SHOULD PROVIDE FAVORABLE LOW-LEVEL
SHEAR PROFILES FOR TORNADOES WITH AN ISOLATED STRONG TORNADO THREAT
POSSIBLE FROM THE JET CENTER WWD ACROSS WRN OK WHERE 30 PERCENT AND
SIGNIFICANT SEVERE PROBABILITY CONTOURS HAVE BEEN ADDED. SEVERE
STORMS WILL ALSO BE POSSIBLE IN NW AND WCNTRL TX EARLY WEDNESDAY
EVENING. HOWEVER...THE MODELS SUGGEST THE CAP WILL LIMIT CONVECTIVE
COVERAGE SOUTH OF THE RED RIVER. SEVERE STORMS WILL ALSO BE POSSIBLE
NWWD ACROSS SRN KS INTO FAR ERN CO WHERE THE MODELS FORECAST
MODERATE INSTABILITY AND DEEP LAYER SHEAR.
THE MAIN UNCERTAINTIES CONCERNING THE SEVERE POTENTIAL WEDNESDAY
INVOLVE THE TIMING OF THE UPPER-LEVEL TROUGH. IF THE UPPER-LEVEL
TROUGH ENDS UP BEING SLOWER THAN IS CURRENTLY FORECAST AND THE
DRYLINE IS SETUP FURTHER WEST...THE WRN PARTS OF THE SLIGHT RISK
AREA WOULD BE FAVORED.
..BROYLES.. 05/17/2010
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