SWODY1
SPC AC 251955
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT SUN MAR 25 2012
VALID 252000Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF ERN NC...
A FEW CHANGES HAVE BEEN MADE TO THE OUTLOOK AT 20Z. THE FIRST IS TO
MAKE THE SLIGHT RISK AREA SMALLER TO ENCOMPASS ONLY ERN NC WHERE
MESOANALYSIS ESTIMATES MLCAPE VALUES ARE AROUND 1000 J/KG. HAVE
REMOVED THE PORTION OF SERN VA WHERE INSTABILITY SHOULD REMAIN VERY
WEAK. THE SECOND CHANGE IS TO REMOVE A SMALL PART OF NERN VA AND SRN
MD FROM THUNDER WHERE THUNDERSTORM ACTIVITY IS NOT EXPECTED THIS
AFTERNOON OR EVENING DUE TO A LACK OF INSTABILITY. THE THIRD CHANGE
IS TO ADD LOW END PROBABILITIES FOR TORNADO AND WIND DAMAGE TO THE
LA BASIN...REFERENCE MCD 360.
..BROYLES.. 03/25/2012
.PREV DISCUSSION... /ISSUED 1049 AM CDT SUN MAR 25 2012/
...ERN NC...
POTENT UPPER LOW THAT HAS TAKEN OVER A WEEK TO CROSS THE CONUS WILL
FINALLY PASS OFF THE MID ATLANTIC COAST LATE TONIGHT. ANOTHER DAY OF
TSTMS WITH HAIL APPEAR LIKELY FOR PARTS OF NC PRIOR TO THE PASSAGE
OF THE UPPER LOW AND ITS ASSOCIATED COLD POOL. FROM THE SANDHILLS
ACROSS THE COASTAL PLAIN VIS SATL IMAGERY REVEALS BREAKS IN THE
CLOUDS AND POTENTIAL FOR LOCALLY STRONGER SURFACE HEATING TO OCCUR
AHEAD OF THE APPROACHING UPPER SYSTEM. COMBINED WITH SURFACE
DEWPOINTS AROUND 60F AND STEEPENING MID LEVEL LAPSE NEAR THE LOW
CENTER...AFTERNOON SBCAPE VALUES OF 700-1200 J/KG APPEAR POSSIBLE.
LOW THROUGH MID-LEVEL FLOW COINCIDENT WITH THE INCREASE IN
CONVECTION IS FORECAST TO BE WEAK AND RESULT IN STORMS THAT WILL
STRUGGLE TO ORGANIZE/PERSIST. HOWEVER...THE DEGREE OF INSTABILITY
AND BACKGROUND AMBIENT VORTICITY...AND LOW FREEZING LEVELS...WILL
CONTRIBUTE TO EFFICIENT HAIL PRODUCTION FROM THE STORMS THAT DO
DEVELOP. AN ENSEMBLE OF SPC HAILCAST MODEL OUTPUT SUGGESTS SOME
STORMS MAY PRODUCE HAIL AROUND 1 INCH IN DIAMETER BUT MOST UPDRAFTS
ARE EXPECTED TO REMAIN INSUFFICIENTLY ROBUST FOR SEVERE HAIL.
...SRN CA...
DEEP COLD CORE LOW ABOUT 250 MILES WEST OF THE CHANNEL ISLANDS OFF
THE SRN CA COAST WILL CONTINUE TO PROGRESS EAST THROUGH LATE TODAY.
THIS SYSTEM APPEARS QUITE STRONG ON VIS SATL IMAGERY AND INCREASING
ASCENT/DECREASING STATIC STABILITY OCCURRING AMIDST A MOIST AIRMASS
SHOULD CONTRIBUTE TO TSTMS AND SQUALLS MOVING INTO THE COASTAL AREAS
AND MOUNTAINS OF SRN CA LATER TODAY. WHILE CONVECTIVE INSTABILITY IS
FORECAST TO REMAIN MEAGER GIVEN GENERALLY COOL/MOIST ENVIRONMENTAL
PROFILES...A LOW PROBABILITY FORECAST OF MARGINALLY SEVERE
HAIL...PERHAPS TO 1 INCH IN DIAMETER...APPEARS WARRANTED WITH THIS
SYSTEM.
...NRN PLAINS...
THUNDER AND HAIL PROBABILITIES HAVE BEEN REMOVED FROM THIS REGION
DUE TO LATEST GUIDANCE INDICATING STRONG CAPPING....LIMITED
MOISTURE...AND WEAK FORCING ALL PROVING HOSTILE TO STORM DEVELOPMENT
THIS PERIOD. WHILE AN ISOLD TSTM CANNOT BE COMPLETELY RULED
OUT...THE GREATER POTENTIAL APPEARS TO EVOLVE PRIMARILY BEYOND THIS
FORECAST PERIOD...AFTER 12Z MONDAY.
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