| May 25, 2013 1300 UTC Day 1 Convective Outlook | ||||||||||||||||||
| Updated: Sat May 25 12:49:38 UTC 2013 | ||||||||||||||||||
| Probabilistic to Categorical Outlook Conversion Table |
| Categorical Graphic | ||||||||||||||||||
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| Probabilistic Tornado Graphic | ||||||||||||||||||
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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| Probabilistic Damaging Wind Graphic | ||||||||||||||||||
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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| Probabilistic Large Hail Graphic | ||||||||||||||||||
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 251245
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT SAT MAY 25 2013
VALID 251300Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL AND NRN
PLNS...
...SYNOPSIS...
LITTLE CHANGE IN THE LARGE-SCALE PATTERN EXPECTED THIS PERIOD AS A
RIDGE REMAINS STNRY OVER THE CNTRL PLNS/UPR MS VLY...BETWEEN SLOWLY
PROGRESSIVE LOWS OVER THE PACIFIC NW AND SRN NEW ENGLAND. FARTHER
S...A WEAKLY ORGANIZED MID/UPR-LVL TROUGH WILL DRIFT SLOWLY E/NE
TOWARD THE ARKLATEX. AT THE SFC...A LEE TROUGH/DRYLINE SHOULD
PERSIST OVER THE NRN/CNTRL HIGH PLNS AS A NW-SE WARM FRONT ADVANCES
SLOWLY N ACROSS CNTRL/NRN PLNS. STRONG TO POSSIBLY SVR TSTM
DEVELOPMENT WILL FOCUS ALONG BOTH THE LEE TROUGH AND FRONT LATER
TODAY INTO SUN.
...CNTRL/NRN PLNS THIS AFTN/EVE...
PERSISTENT SELY FLOW E OF LEE TROUGH WILL CONTINUE TO ADVECT LOW-LVL
MOISTURE NWWD ACROSS THE NRN HALF OF THE PLNS TODAY...WITH SFC
DEWPOINTS IN THE MID 50S F EXPECTED BY EVE IN FAR ERN MT/WRN
ND...AND VALUES WELL INTO THE 60S LIKELY OVER WRN SD AND MUCH OF
NEB. AT THE SAME TIME...MODERATE SWLY MID-LVL FLOW WILL MAINTAIN
DEEP EML ACROSS REGION. COUPLED WITH DAYTIME HEATING...AFTN SBCAPE
SHOULD RANGE FROM AROUND 1500 J/KG IN ERN MT/WRN ND TO NEAR 2500
J/KG IN CNTRL NEB.
EML CAP LIKELY WILL DELAY SFC-BASED TSTM DEVELOPMENT UNTIL MID AFTN
IN MOST AREAS. THE EARLIEST DEVELOPMENT MAY OCCUR OVER SE MT...NE
WY...AND WRN SD /BLACK HILLS AREA/...WHERE LOW-LVL
CONVERGENCE/UPSLOPE FLOW SHOULD BE GREATEST. THE STORMS SHOULD THEN
MOVE/DEVELOP ESE INTO LOW-LVL MOIST AXIS OVER WRN PORTIONS OF THE
LWR PLNS THIS EVE THROUGH EARLY SUN.
WHILE NO NOTEWORTHY UPR-LVL DISTURBANCE IS APPARENT IN STLT IMAGERY
TO BOLSTER STORM STRENGTH/LONGEVITY...REGION WILL LIE BENEATH SRN
FRINGE OF THE MAIN BELT OF THE WLYS...WITH AMPLE /35-40 KT/ WSWLY
DEEP SHEAR FOR SUPERCELLS. VERY LARGE HAIL SHOULD BE THE MAIN SVR
THREAT INITIALLY...ALTHOUGH TORNADOES ALSO MAY OCCUR. WITH TIME THE
STORMS SHOULD MERGE INTO LINES/CLUSTERS THAT YIELD AN INCREASING
RISK FOR DMGG WIND INTO THE EVE. THIS THREAT MAY PERSIST INTO EARLY
SUN ALONG WARM FRONT OVER PARTS OF NEB AND SD...AIDED BY
NOCTURNALLY-STRENGTHENED SLY LLJ.
...SRN HIGH PLNS...
MORE ISOLD TO WDLY SCTD STORMS SHOULD ONCE AGAIN FORM ALONG SRN HALF
OF LEE TROUGH FROM WRN KS SSW THROUGH THE OK/TX PANHANDLES INTO ERN
NM. THESE STORMS WILL EXIST IN COMPARATIVELY WEAK DEEP SHEAR AND
MODEST MOISTURE. BUT STEEP LOW TO MID-LVL LAPSE RATES AND 25+ DEG
LOW LEVEL TEMP-DEWPOINT SPREADS MAY YIELD A FEW STORMS WITH LARGE
HAIL AND LOCALLY DMGG WIND.
...CNTRL/E TX TODAY/TNGT...
SFC HEATING MAY PROMOTE THE DEVELOPMENT OF PERIODIC CLUSTERS OF
STRONG TSTMS ALONG THE OUTER FRINGES OF SLOWLY-MOVING TX UPR SYSTEM
TODAY...AND ADDITIONAL DEVELOPMENT CLOSER TO THE CENTER OF THE MAIN
VORT ONCE AGAIN TNGT/EARLY SUN. WHILE DEEP SHEAR WILL REMAIN
WEAK...SOME DEGREE OF LOW-LVL SPEED AND DIRECTIONAL SHEAR WILL
PERSIST IN WARM/HUMID ENVIRONMENT ON THE E SIDE OF THE UPR SYSTEM.
THIS SETUP MAY YIELD OCCASIONAL EMBEDDED AREAS OF LOW-LVL
ROTATION...AND POSSIBLY A BRIEF TORNADO OR TWO. THE OVERALL SVR RISK
DOES...HOWEVER...APPEAR TOO WEAK/UNFOCUSED TO WARRANT MORE THAN THE
LOWEST CONDITIONAL PROBABILITIES ATTM.
..CORFIDI/MARSH.. 05/25/2013
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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