SWODY1
SPC AC 220513
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1213 AM CDT WED APR 22 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
FULL-LATITUDE TROUGH OVER THE ERN CONUS WILL BEGIN TO LIFT NEWD INTO
THE ATLANTIC IN RESPONSE TO SEWD PROGRESSION OF NEXT UPSTREAM SYSTEM
THROUGH WRN CANADA INTO THE PACIFIC NW AND NRN ROCKIES. AS THIS
OCCURS...WEAK MIDLEVEL IMPULSE CURRENTLY OVER NRN UT WILL TRANSLATE
EWD WITHIN INCREASINGLY ZONAL FLOW PATTERN...EMERGING INTO THE CNTRL
HIGH PLAINS LATER THIS AFTERNOON.
IN THE LOW LEVELS...AFTERNOON SURFACE PATTERN WILL FEATURE LOW
PRESSURE CENTERS OVER SERN MANITOBA AND NWRN TX WITH A STRENGTHENING
LEE TROUGH OVER THE HIGH PLAINS. AN ASSOCIATED WARM FRONT WILL
INTENSIFY THROUGH THE PERIOD FROM THE MANITOBA LOW CENTER SEWD
THROUGH THE DAKOTAS INTO MID MS VALLEY. FARTHER S...A WARM OR
STATIONARY BOUNDARY WILL STRETCH ESEWD FROM THE LOW OVER NWRN TX
INTO THE LOWER MS VALLEY.
...CNTRL/SRN PLAINS...
BOUNDARY LAYER WILL REMAIN RATHER DRY E OF STRENGTHENING LEE TROUGH
WITH DEWPOINTS LARGELY IN THE 40S. HOWEVER...FORECAST SOUNDINGS
INDICATE THAT ENVIRONMENT WILL BE CHARACTERIZED BY STEEP
LOW/MID-TROPOSPHERIC LAPSE RATES WHICH WILL LARGELY CONTRIBUTE TO
AFTERNOON MLCAPE APPROACHING 500 J/KG ALONG CNTRL HIGH PLAINS
PORTION OF LEE TROUGH. LATEST MODEL GUIDANCE SUGGESTS THAT DEEP
MIXING/CONVERGENCE ALONG THIS BOUNDARY IN CONCERT WITH INCREASED
FORCING FOR ASCENT IN ADVANCE OF ABOVE-MENTIONED SHORT WAVE TROUGH
MAY BE SUFFICIENT TO INITIATE ISOLATED STORMS BY LATE
AFTERNOON/EARLY EVENING. DEEP-LAYER VERTICAL SHEAR WILL REMAIN ON
THE MARGINS /I.E. AROUND 30 KT THROUGH THE LOWEST 6 KM/ OF THAT
SUPPORTIVE OF UPDRAFT SUSTENANCE/ROTATION. WHEN COUPLED WITH THE
STEEP LAPSE RATES...SETUP MAY YIELD SOME HAIL AND LOCALLY STRONG
WIND GUSTS THROUGH THE LATE AFTERNOON AND EVENING HOURS.
FARTHER S ALONG LEE TROUGH AND WARM/STATIONARY FRONT...A STRONGER
CAP AND THE ABSENCE OF ANY APPRECIABLE FORCING MECHANISMS ARE
EXPECTED TO INHIBIT ANY DEEP MOIST CONVECTION THROUGH THE DIURNAL
HEATING CYCLE.
ELEVATED TSTMS WILL BE POSSIBLE LATER TONIGHT IN A BAND OF
STRENGTHENING WAA/ISENTROPIC ASCENT FROM KS/NEB INTO THE OZARK
PLATEAU...ROOTED ABOVE EML/STRONG CAP. SOME HAIL WILL BE POSSIBLE
WITH THE STRONGER STORMS GIVEN THE STEEP MIDLEVEL LAPSE RATES AND
MUCAPE APPROACHING 1000 J/KG.
...OH VALLEY...
DEEP-LAYER ASCENT ASSOCIATED WITH VORTICITY MAXIMUM/MIDLEVEL JET
STREAK DIGGING SEWD THROUGH THE UPPER GREAT LAKES MAY SERVE TO FOCUS
A CLUSTER OF LOW-TOPPED TSTMS OVER THE UPPER OH VALLEY THIS
AFTERNOON. GIVEN THE STEEP LAPSE RATES AND QUITE COOL THERMODYNAMIC
PROFILES...ENVIRONMENT WILL BE SUPPORTIVE OF SOME HAIL INTO THIS
EVENING.
..MEAD/SMITH.. 04/22/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment