SWODY1
SPC AC 140542
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1242 AM CDT FRI AUG 14 2009
VALID 141200Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN PLAINS INTO NRN
MN...
...THERE IS A SLGT RISK OF SVR TSTMS OVER MUCH OF CENTRAL/ERN MT...
...UPPER MS VALLEY TO SOUTHERN MT...
GRADUAL MOISTENING ACROSS THE NRN PLAINS SHOULD CONTRIBUTE GREATLY
TOWARDS CONVECTIVE POTENTIAL FROM MT INTO NRN MN FRIDAY. LATEST
MODEL GUIDANCE AND SATELLITE IMAGERY SUGGEST LARGE SCALE FORCING
WILL INCREASE ACROSS THE DAKOTAS EARLY AHEAD OF LEAD SHORTWAVE
TROUGH. THIS FEATURE APPEARS PARTLY RESPONSIBLE FOR ONGOING
CONVECTION ACROSS ERN MT INTO WRN ND EARLY THIS MORNING. LATEST
THINKING IS CONVECTION WILL MIGRATE ACROSS THE DAKOTAS EARLY AS LLJ
WILL BE SHUNTED EAST INTO CNTRL SD BY 18Z BEFORE VEERING ALONG
FRONTAL ZONE INTO NRN MN BY LATE AFTERNOON. WITH TIME...STRONGEST
BOUNDARY LAYER HEATING/STEEP LOW LEVEL LAPSE RATES WILL OCCUR
IMMEDIATELY AHEAD OF WEAK SFC LOW ACROSS THE NRN RED RIVER
VALLEY...ENHANCING THE PROSPECTS FOR SFC BASED THUNDERSTORM
DEVELOPMENT ALONG ADVANCING WIND SHIFT...AND ALONG NARROW ZONE
IMMEDIATELY NORTH OF FRONTAL ZONE DUE TO WARM ADVECTION. SHEAR
PROFILES FAVOR ORGANIZED MULTI-CELL CLUSTERS WITHIN THE WARM
ADVECTION ZONE...AND PERHAPS A FEW WEAK SUPERCELLS NEAR THE WARM
SECTOR...THOUGH PARAMETERS SEEM MORE CONDUCIVE FOR CLUSTERING GIVEN
THAT LARGE SCALE FORCING WILL LIKELY CONTRIBUTE TO STORM MERGERS.
FARTHER WEST...STRONG FORCING WILL SPREAD ACROSS THE NRN ROCKIES IN
ASSOCIATION WITH 50-60KT MID LEVEL JET THAT WILL EJECT ACROSS MT
DURING THE LATTER HALF OF THE PERIOD. IN ALL LIKELIHOOD A FAIRLY
SHARP BAROCLINIC ZONE WILL DEVELOP WITHIN EXIT REGION OF THIS
FEATURE WHICH APPEARS TO TIME INTO CENTRAL MT BETWEEN 21-00Z.
ALTHOUGH BUOYANCY WILL BE SOMEWHAT MARGINAL...MUCAPE ON THE ORDER OF
1000 J/KG...KINEMATIC ENVIRONMENT SUGGESTS A SQUALL LINE WILL EMERGE
ALONG ADVANCING COLD FRONT...WITH PERHAPS AN ISOLATED SUPERCELL
THREAT TOWARD THE MT/WY BORDER. DAMAGING WINDS AND HAIL COULD
ACCOMPANY THIS ACTIVITY AS IT SPREADS ACROSS CNTRL/ERN MT WELL INTO
THE EVENING HOURS.
...CENTRAL HIGH PLAINS...
LATEST SATELLITE IMAGERY CLEARLY DEPICTS A WELL DEFINED UPPER
VORT/SHORTWAVE TROUGH OVER NRN AZ EARLY THIS MORNING. THIS FEATURE
WILL EJECT NEWD ACROSS THE 4-CORNERS REGION TOWARD THE CNTRL/SRN
HIGH PLAINS BY 15/00Z. CONTINUED MOISTENING SHOULD OCCUR ACROSS THE
TX SOUTH PLAINS...NWD INTO WRN NEB WHERE PWAT VALUES WILL EXCEED
1.5 INCHES. THIS AIRMASS WILL UNDOUBTEDLY CONVECT BY MID-LATE
AFTERNOON AS ANY BOUNDARY LAYER HEATING WILL PROVIDE THE BUOYANCY
AND REMOVE THE INHIBITION FOR THUNDERSTORM DEVELOPMENT AHEAD OF
MOIST UPPER TROUGH. AT THIS TIME WILL NOT INTRODUCE SLIGHT RISK AS
SHEAR PROFILES ARE EXPECTED TO REMAIN SOMEWHAT MARGINAL.
..DARROW/GRAMS.. 08/14/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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