SPC AC 020622
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1222 AM CST FRI JAN 02 2009
VALID 031200Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN TX INTO THE LOWER MS
VALLEY...
...SYNOPSIS...
LARGE-SCALE PATTERN WILL REMAIN PROGRESSIVE THROUGH THE DAY TWO
PERIOD AS DYNAMIC MIDLEVEL TROUGH TRANSLATES FROM THE NRN ROCKIES
AND GREAT BASIN EWD INTO THE NRN AND CNTRL PLAINS. A LEAD...LOWER
LATITUDE IMPULSE INITIALLY OVER THE SRN PLAINS WILL DEAMPLIFY
THROUGH THE PERIOD WHILE SHIFTING NEWD THROUGH THE MIDDLE/LOWER MS
VALLEYS.
IN THE LOW LEVELS...DIFFERENCES DO EXIST IN THE TRACK OF PRIMARY
SURFACE LOW...BUT IN GENERAL...THIS FEATURE WILL DEVELOP FROM WRN KS
SEWD TOWARD CNTRL OK BEFORE RAPIDLY LIFTING NEWD INTO IL/IND BY
SUNDAY MORNING. TRAILING COLD FRONT WILL PUSH SEWD THROUGH THE
CNTRL AND SRN PLAINS...EVENTUALLY REACHING THE MIDDLE/LOWER MS
VALLEY LATE SATURDAY NIGHT. MEANWHILE...SYNOPTIC WARM FRONT WILL
LIFT NEWD THROUGH THE TN INTO OH VALLEY.
...ERN TX INTO LOWER MS VALLEY...
02/00Z REGIONAL SOUNDINGS AND CURRENT SURFACE OBSERVATIONS INDICATE
THAT A MODIFIED AIR MASS IS ALREADY RETURNING NWD THROUGH SRN/ERN TX
AND LA. THIS PROCESS WILL BE HASTENED DURING THE LATTER HALF OF THE
DAY ONE PERIOD INTO DAY TWO AS A SWLY LLJ DEVELOPS OVER SRN PLAINS
INTO LOWER MS VALLEY. DESPITE INTERVENING CLOUDS AND
PRECIPITATION...BOUNDARY LAYER DEWPOINTS IN THE LOW/MID 60S IN
CONJUNCTION WITH MODEST EML PLUME PRECEDING LEAD SHORT WAVE TROUGH
WILL CONTRIBUTE TO AIR MASS DESTABILIZATION WITH MLCAPE INCREASING
TO 500-1000 J/KG.
TSTMS ARE EXPECTED TO BE ONGOING SATURDAY MORNING OVER PARTS OF ERN
TX...DRIVEN BY DEEP-LAYER ASCENT IN ADVANCE OF SHORT WAVE TROUGH AND
IN LEFT EXIT REGION OF SUBTROPICAL JET STREAK PROPAGATING EWD INTO
THE NWRN GULF BASIN. EXPECT TSTMS TO SLOWLY INTENSIFY THROUGH THE
DAY WHILE MOVING/DEVELOPING EWD/NEWD INTO GRADUALLY DESTABILIZING
AIR MASS OVER LA/MS. WHILE MIDLEVEL WIND FIELDS WILL NOT BE
PARTICULARLY STRONG /45-55 KT/...PROXIMITY OF 40-45 KT LLJ WILL
RESULT IN SUFFICIENT LOW AND DEEP-LAYER SHEAR FOR EMBEDDED SUPERCELL
AND BOWING STRUCTURES CAPABLE OF DAMAGING WIND GUSTS AND PERHAPS A
COUPLE OF TORNADOES.
AN ISOLATED SEVERE STORM THREAT MAY CONTINUE INTO SATURDAY NIGHT
OVER PARTS OF W-CNTRL/SWRN AL. HOWEVER...WEAKENING FORCING FOR
ASCENT AND DECREASING INSTABILITY WITH TIME SHOULD TEND TO LIMIT A
MORE SUBSTANTIAL SEVERE WEATHER THREAT OVERNIGHT.
..MEAD.. 01/02/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
|
