Saturday, March 7, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071619
SWODY1
SPC AC 071615

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1015 AM CST SAT MAR 07 2009

VALID 071630Z - 081200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE
SRN/CENTRAL PLAINS ACROSS THE MID MS RIVER VALLEY...

...PORTIONS OF OK/KS NEWD ACROSS THE MID MS RIVER VALLEY...
MORNING WV IMAGERY INDICATES WELL DEFINED SYSTEM ALREADY EJECTING
ACROSS ERN CO...WITH TRAILING IMPULSE DIGGING TOWARDS THE FOUR
CORNERS REGION. TRAILING/STRONG UPPER LOW NOW OVER THE GREAT BASIN
WILL EJECT ENEWD AS A NEGATIVELY TILTED SHORTWAVE TROUGH ACROSS THE
CENTRAL PLAINS THROUGH TONIGHT. THIS FEATURE WILL CONTINUE TO BE
MAIN CONTRIBUTOR TO THUNDERSTORM DEVELOPMENT ACROSS PORTIONS OF THE
SRN/CENTRAL PLAINS NEWD INTO THE SRN GREAT LAKES REGION LATER TODAY
AND TONIGHT. AT THE SURFACE...A FRONT WILL REMAIN DRAPED FROM
VICINITY LAKE ERIE WSWWD INTO NRN MO AND SWRN KS WHERE A LOW WILL
DEEPEN TODAY. THIS LOW WILL THEN TRACK GENERALLY ENEWD INTO CENTRAL
MO WITH TRAILING COLD FRONT ACCELERATING ESEWD ACROSS THE SRN HIGH
PLAINS THROUGH THE LATTER HALF OF THE PERIOD.

ALTHOUGH WINDS ALOFT WILL BECOME ENHANCED ACROSS THIS REGION AS 90+
KT MID LEVEL JET /130+ KT H25 SPEED MAX/ ACCOMPANIES EJECTING TROUGH
ACROSS OK BY LATE TONIGHT...PRIMARY LIMITING FACTOR FOR A MORE
ACTIVE SEVERE WEATHER THREAT CONTINUES TO BE RELATIVELY DRY AIR MASS
PRECEEDING THE SYSTEM. PW/S REMAIN NEAR OR JUST UNDER 1 INCH WITH
H85 DEW POINTS LESS THAN 9C OVER THE SRN PLAINS. REGARDLESS...VERY
COLD MID LEVEL AIR/STEEP LAPSE RATES AND STRENGTHENING DEEP ASCENT
SHOULD OVERCOME THE LIMITED MOISTURE AND LIKELY SUPPORT SCATTERED
STRONG TO SEVERE THUNDERSTORMS SPREADING ENEWD FROM KS/NRN MO ACROSS
THE MID MS RIVER VALLEY LATE TODAY AND TONIGHT.

12Z NAM AND RUC FORECAST WEAKER CAP NEAR THE FRONT/DEVELOPING DRY
LINE ACROSS KS AND INTO THE TX PANHANDLE REGION THIS
AFTERNOON...WHILE GFS MAINTAINS STRONGER CAP ACROSS THE WARM SECTOR.
ALTHOUGH ALL AGREE IN DEVELOPING ELEVATED THUNDERSTORMS NORTH OF
THE BOUNDARY FROM NRN KS/NRN MO ACROSS THE MID MS RIVER VALLEY
BEGINNING LATER TODAY AND INCREASING OVERNIGHT ALONG NOSE OF
STRENGTHENING LLJ. LARGE HAIL WILL BE PRIMARY THREAT WITH THIS
ACTIVITY...WHICH SHOULD EVOLVE AS ONE OR TWO CLUSTERS/MCSS THROUGH
THE PERIOD. WILL MAINTAIN CONDITIONAL RISK/LOW PROBABILITIES OF
DIURNAL DEVELOPMENT NEAR THE FRONT/SURFACE LOW THIS AFTERNOON / AS
FORECAST BY THE NAM/RUC / GIVEN THE VERY STRONG/DEEP MIXING TODAY.
MORE LIKELY SURFACE DEVELOPMENT MAY BE DELAYED UNTIL LATER THIS
EVENING/OVERNIGHT AS STRONG COLD FRONT AND DEEP ASCENT BEGIN TO
SHIFT EWD ACROSS KS/OK. WIND DAMAGE/HAIL WOULD BE PRIMARY WARM
SECTOR THREATS WITH HIGH BASED STORMS WITH ANY DIURNALLY DRIVEN
DEVELOPMENT. ALTHOUGH AS STORMS DEVELOP EWD INTO RICHER MOISTURE
AHEAD OF COLD FRONT LATER TONIGHT OVER PORTIONS OF NERN OK/SERN
KS/SWRN MO...STORM INTENSITY/ORGANIZATION AND OVERALL TORNADO
POTENTIAL WILL LIKELY INCREASE.

..EVANS/SMITH.. 03/07/2009

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