SWODY1
SPC AC 261959
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0159 PM CST MON JAN 26 2009
VALID 262000Z - 271200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
DOMINANT UPPER AIR FEATURE FOR REMAINDER PERIOD WILL BE
STG/POSITIVELY-TILTED TROUGH -- EVIDENT ATTM FROM NRN ROCKIES SWWD
ACROSS SRN NV AND SRN CA. THIS TROUGH IS EXPECTED TO MOVE SLOWLY
EWD THROUGH 27/12Z. TO ITS E...STG LOW LEVEL WAA AND ISENTROPIC
REGIME IS FCST OVER SRN PLAINS NEWD TO OH VALLEY...ATOP LOW LEVEL
FRONTAL ZONE. SFC REFLECTION OF THAT FRONT APPEARS IN TWO SEGMENTS:
1. QUASISTATIONARY SYNOPTIC BOUNDARY FROM SRN FL WNWWD ACROSS NWRN
GULF AND S-CENTRAL TX
2. STRENGTHENING SFC-925 MB FRONTAL ZONE EVIDENT FROM S-CENTRAL TX
NEWD TO VICINITY MWL...BECOMING DIFFUSE FARTHER NE ACROSS SERN OK.
FRONTAL ZONES SHOULD MERGE THROUGH END OF PERIOD...WITH DOMINANT
BOUNDARY ASSUMING POSITION FROM LOWER PECOS VALLEY REGION NEWD
ACROSS N-CENTRAL TX TO SWRN AR BY 12Z.
...SRN GREAT BASIN/NRN AZ REGION...
STG MIDLEVEL LARGE-SCALE ASCENT -- IMMEDIATELY AHEAD OF TROUGH --
WILL STEEPEN LAPSE RATED JUST ENOUGH FOR ISOLATED/EPISODIC
THUNDER...IN COMBINATION WITH MRGL LOW-MIDLEVEL MOISTURE. SOME OF
THIS ACTIVITY WILL BE IN FORM OF THUNDERSNOW...ELEVATION DEPENDENT.
MUCAPE UP TO ABOUT 300 J/KG IS POSSIBLE THIS AFTERNOON...SOME OF
WHICH SHOULD REACH UPWARD INTO FAVORABLE ICING LAYERS FOR LTG
GENERATION...PER MODIFIED RUC SOUNDINGS. VIS IMAGERY ALREADY SHOWS
SHALLOW AND STRONGLY SHEARED CB DEVELOPING WHERE PROLONGED
INSOLATION HAS TAKEN PLACE. SMALL HAIL MAY FALL FROM DEEPEST AND
MOST VIGOROUS CELLS...HOWEVER...LACK OF MORE ROBUST LOW LEVEL THETAE
SHOULD KEEP SVR THREAT TOO WEAK FOR AOA 5-PERCENT PROBABILITIES.
...SRN PLAINS TO OZARKS...
THUNDER POTENTIAL IS FCST TO PEAK AROUND 08Z-10Z TIME FRAME ACROSS
OUTLOOK AREA...THEN SHIFT EWD AND DIMINISH CONSIDERABLY AROUND 12Z.
PERSISTENT/ELEVATED MOISTURE TRANSPORT AND JUXTAPOSED WAA ARE
EXPECTED ALONG WRN FRINGES OF 40-55 KT SWLY LLJ OVERNIGHT. ELEVATED
MUCAPE APCHG 300 J/KG IS POSSIBLE.ROOTED AROUND 850 MB OVER N TX AND
800 MB NWD OVER CENTRAL OK. MODIFIED NAM-KF FCST SOUNDINGS SUGGEST
THIS BUOYANCY WILL BE CAPPED BY PRONOUNCED STABLE LAYER LOCATED
BETWEEN 450-500 MB...AND AOB HEIGHT LEVEL OF -20 DEG C ISOTHERM.
THIS SORT OF THERMODYNAMIC STRUCTURE INDICATES THAT...WHILE
SHOWERY/CONVECTIVE BURSTS OF FREEZING/FROZEN PRECIP ARE QUITE LIKELY
ACROSS MUCH OF THIS REGION...THUNDER WILL BE ONLY ISOLATED TO WIDELY
SCATTERED IN NATURE.
..EDWARDS.. 01/26/2009
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