Thursday, March 18, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 181949
SWODY1
SPC AC 181948

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0248 PM CDT THU MAR 18 2010

VALID 182000Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

THE ONLY CHANGE FOR THE 20Z OUTLOOK IS TO ADD A THUNDER LINE IN ERN
NC WHERE A FEW LIGHTNING STRIKES MAY OCCUR THIS AFTERNOON. THE
CONVECTION IS ASSOCIATED WITH COLD AIR ALOFT AND LARGE-SCALE ASCENT
JUST AHEAD OF AN UPPER-LEVEL TROUGH WHICH WILL MOVE AWAY FROM THE
ERN SEABOARD THIS EVENING.

..BROYLES.. 03/18/2010

.PREV DISCUSSION... /ISSUED 1041 AM CDT THU MAR 18 2010/

...SYNOPSIS...
A CONTINENTAL POLAR AIR MASS REMAINS OVER MUCH OF THE CONUS THIS
MORNING WITH LITTLE IN THE WAY OF ANY MOISTURE SOURCE FOR
THUNDERSTORMS. A DEEP UPPER TROUGH OVER THE SERN U.S. WILL MAINTAIN
NWLY FLOW ACROSS THE SRN PLAINS/LOWER MS VALLEY WITH A SFC
ANTICYCLONE CENTERED OVER E TX THIS AFTERNOON. TO THE NW...THE
FEATURE OF INTEREST WILL BE A COLD FRONT THAT WILL EXTEND FROM THE
GREAT BASIN INTO THE CNTRL PLAINS LATER TODAY AND TONIGHT. ISOLATED
THUNDERSTORMS WILL BE POSSIBLE NEAR THE FRONT THIS AFTERNOON FROM NV
INTO CO...AS WELL AS ACROSS SW NEB INTO NWRN KS LATE.

...SRN NV INTO SWRN WY/WRN CO...
A POSITIVELY TILTED UPPER TROUGH WILL PROCEED SEWD ACROSS THE GREAT
BASIN TODAY...WITH A COLD FRONT EXTENDING FROM SRN NV TO THE WY/CO
BORDER BY 21Z. STEEPENING LAPSE RATES AND LIFT ALONG THE FRONT WILL
LIKELY RESULT IN ISOLATED WEAK CONVECTION. INSTABILITY WILL BE WEAK
WITH MUCAPE VALUES ON THE ORDER OF 200-300 J/KG. WHILE LOCALLY
STRONG WIND GUSTS MAY OCCUR...WEAK INSTABILITY AND LOW TO MID LEVEL
WIND FIELDS SHOULD RESULT IN MAINLY SUB-SEVERE CONVECTION.

...SWRN NEB AND NWRN KS OVERNIGHT...
DEEP FRONTOGENETICAL FORCING BEHIND A COLD FRONT AND COOLING ALOFT
WITH THE APPROACHING TROUGH MAY RESULT IN ISOLATED THUNDERSTORMS
TONIGHT MAINLY OVER SWRN NEB. FORECAST SOUNDINGS SHOW 100-200 J/KG
MUCAPE DEVELOPING...ROOTED AROUND 700 MB. GIVEN THAT MOST OF THE
THERMODYNAMIC PROFILE WILL BE BELOW FREEZING...SNOW OR ICE PELLETS
MAY RESULT.

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