SWODY1
SPC AC 240540
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT SUN AUG 24 2008
VALID 241200Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A PORTION OF THE CNTRL
HIGH PLAINS...
...CNTRL HIGH PLAINS AREA...
LEE TROUGH AND SLY FLOW WILL BECOME ESTABLISHED OVER THE CNTRL HIGH
PLAINS IN WAKE OF RETREATING SURFACE RIDGE. THIS WILL CONTRIBUTE TO
LOW 60S DEWPOINTS ADVECTING NNWWD THROUGH WRN NEB AND SW SD BENEATH
PLUME OF 8 C/KM 850-500 MB LAPSE RATES. MLCAPE FROM 1500-2500 J/KG
WILL BE POSSIBLE AS THE BOUNDARY LAYER WARMS DURING THE AFTERNOON.
THE STEEPER LAPSE RATES WILL CORRESPOND TO A WARM EML SPREADING EWD
INTO THE HIGH PLAINS WITH 700 MB TEMPERATURES FROM 12-14C. THIS WILL
LIKELY CONTRIBUTE TO A CAP EAST OF HIGHER TERRAIN.
HEIGHTS MAY RISE SLIGHTLY DURING THE FIRST HALF OF THE DAY IN WAKE
OF RETREATING UPPER TROUGH MOVING INTO SE CANADA. HOWEVER...A VORT
MAX CURRENTLY MOVING THROUGH ID IS FORECAST TO CREST UPPER RIDGE AND
THEN MOVE ESEWD INTO NE WY...WRN SD AND NW NEB. INITIAL STORMS WILL
MOST LIKELY DEVELOP WITHIN ZONE OF OROGRAPHIC FORCING OVER HIGHER
TERRAIN. ACTIVITY WILL THEN SPREAD SEWD INTO THE HIGH PLAINS DURING
THE EVENING BEFORE WEAKENING AS IT ENCOUNTERS STRONGER CONVECTIVE
INHIBITION AND NOCTURNAL COOLING. FLOW ALOFT WILL REMAIN
MODEST...BUT STRONG VEERING IN THE SURFACE-500 MB LAYER WILL
CONTRIBUTE TO 30-35 KT BULK SHEAR THAT WILL BE MARGINALLY SUFFICIENT
FOR ORGANIZED STORM STRUCTURES. ISOLATED DAMAGING WIND AND LARGE
HAIL WILL BE THE MAIN THREATS.
...SRN HALF OF GULF COASTAL STATES...
FAY HAS BEEN DOWNGRADED TO A TROPICAL DEPRESSION AND WILL LIKELY
REMAIN SO ON SUNDAY GIVEN THAT IT IS EXPECTED TO STAY OVER LAND. THE
STRONGER LOW LEVEL WINDS ARE FORECAST TO ROTATE FROM THE NE THROUGH
NW QUADRANT OF THE STORM...BECOMING FARTHER REMOVED FROM THE FETCH
OF HIGHER THETA-E AIR OFF THE GULF. A MARGINAL THREAT FOR ISOLATED
TORNADOES MAY CONTINUE INTO SUNDAY. HOWEVER...OVERALL THREAT DOES
NOT APPEAR TO WARRANT A CATEGORICAL RISK AT THIS TIME DUE TO
EXPECTED WEAKENING OF WIND FIELDS IN THE ERN HALF OF THE STORM. IF
IT BEGINS TO APPEAR THAT THE LOW LEVEL WINDS ARE SLOWER TO WEAKEN
THAN CURRENTLY ANTICIPATED...THEN A SLIGHT RISK MAY BE REINTRODUCED
IN LATER OUTLOOKS.
...NE OH...NW PA THROUGH THE WRN HALF OF NY...
SRN EXTENTION OF UPPER TROUGH MOVING THROUGH SE CANADA WILL CONTINUE
INTO THE LOWER GREAT LAKES AND NERN U.S. SUNDAY ACCOMPANIED BY A
COLD FRONT. A NARROW AXIS OF INSTABILITY WILL LIKELY DEVELOP ALONG
MOIST AXIS AHEAD OF THE FRONT...BUT WEAK MID LEVEL LAPSE RATES WILL
LIMIT MLCAPE TO GENERALLY AROUND 1000 J/KG.
SCATTERED STORMS WILL LIKELY DEVELOP ALONG FRONT AND LAKE BREEZE
BOUNDARIES AND SPREAD SEWD THROUGH PARTS OF OH...PA AND NY. WEAK
VERTICAL SHEAR WILL SUPPORT MOSTLY MULTICELL STORMS. LOW LEVEL LAPSE
RATES MAY STEEPEN ENOUGH FOR A THREAT OF ISOLATED STRONG WIND GUSTS
THROUGH EARLY EVENING.
..DIAL/JEWELL.. 08/24/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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