Tuesday, October 20, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201546
SWODY1
SPC AC 201544

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1044 AM CDT TUE OCT 20 2009

VALID 201630Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS PARTS OF SERN AZ/SWRN NM AND
FAR WRN TX...

...SERN AZ/NM/FAR WRN TX

VIGOROUS UPPER LOW OVERNIGHT HAS TRACKED SEWD TO CURRENT LOCATION
NWRN AZ. MODELS MOVE THE LOW CENTER TO CENTRAL NM BY 12Z WED WITH
STRONG PVA/MID LEVEL COOLING SPREADING EWD ACROSS ERN AZ INTO WRN NM
THIS AFTERNOON...REACHING SRN HI PLAINS BY WED AM.

VERY MOIST AIR WHICH HAS WORKED NWD THRU WRN MEXICO PAST COUPLE DAYS
IS BEING DRAWN NEWD IN THE STRONGER SWLY FLOW IN ADVANCE OF UPPER
LOW ACROSS SERN AZ INTO SRN NM/FAR WRN TX. PRONOUNCED DRYING NOTED
ON W/V IMAGERY SPREADING EWD ACROSS CENTRAL AZ IN ADVANCE OF UPPER
LOW EXPECTED TO BE ZONE OF STRONGER ASCENT FOR THUNDERSTORM
DEVELOPMENT BY EARLY AFTERNOON.

WITH DEWPOINTS RISING INTO THE MID/UPPER 50S PRIOR TO THE ARRIVAL OF
DRYING AND TROUGH...SURFACE TEMPERATURES RISING INTO THE MID 70S
SERN AZ VALLEYS EXPECTED TO BE SUFFICIENT TO INITIATE SURFACE BASED
THUNDERSTORMS. WITH STEEP LAPSE RATES...7-8C/KM...MLCAPES UP TO
1000 J/KG...AND DEEP LAYER SHEAR OF 40-50KT...CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS. STORMS SHOULD INITIATE VICINITY
HIGHER TERRAIN FROM ERN RIM/WHITE MTNS SWD IN SERN AZ AND QUICKLY
MOVE/DEVELOP EWD ACROSS LOWER ELEVATIONS AND INTO SWRN NM/FAR WRN
TX.

LARGE HAIL AND LOCALLY DAMAGING WINDS WILL BE LIKELY WITH THE
STRONGEST ACTIVITY...WITH PARAMETERS FAVORABLE FOR ROTATING
STORMS...ENHANCING THE SEVERE CONCERN...PARTICULARLY FOR LARGE HAIL.


WITH GREATER INSTABILITY NOW EXPECTED...THIS AREA HAS BEEN UPGRADED
TO A SLIGHT RISK FOR THIS AFTERNOON AND EVENING.

...SRN/CNTRL HI PLNS...
A MODIFIED CP AIR MASS /WITH SFC DEW POINTS IN THE LOW 50S/ WILL
CONTINUE TO RETURN NWD ACROSS THE SRN AND CNTRL HI PLNS TODAY IN
STRENGTHENING SLY FLOW AHEAD OF LEE TROUGH. SIMILAR TO MON...
HEATING/BOUNDARY LAYER DEEPENING WILL ERODE CIN NOW PRESENT OVER
REGION TO SUPPORT ISOLD/SCTD STORMS BY MID/LATE AFTN ALONG LEE
TROUGH...WHERE SBCAPE WILL BE AROUND 500 J/KG.

THE STRONGER MID/HI LVL FLOW/SHEAR ASSOCIATED WITH AZ UPR TROUGH
WILL REMAIN W OF THE REGION THROUGH THE DAY. THUS...ENVIRONMENT
WILL BE MOST SUPPORTIVE OF MULTICELL CLUSTERS CAPABLE OF GUSTY WINDS
AND POSSIBLY MARGINALLY SVR HAIL. STRENGTHENING NOCTURNAL LLJ AND
INCREASING FORCING FOR ASCENT SHOULD RESULT IN AN INCREASE IN STORM
COVERAGE AND LARGER SCALE ORGANIZATION TONIGHT FROM ERN NM/WRN TX
NEWD INTO WRN KS/S-CNTRL NEB. THIS ACTIVITY MAY CONTINUE TO POSE A
THREAT FOR ISOLD DMGG WIND AND MARGINALLY SVR HAIL.

..HALES/HURLBUT.. 10/20/2009

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