DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 082001
SWODY1
SPC AC 081958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT MON JUL 08 2013

VALID 082000Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM MT ACROSS THE NRN PLAINS
INTO THE MIDDLE MO RIVER VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS FRM SERN LOWER MI INTO NRN
OH...

...MT/ND...
AS A STRONG SHORTWAVE TROUGH PROGRESSES EWD ACROSS THE NRN
INTERMOUNTAIN WEST TOWARD THE NRN ROCKIES...SCATTERED STRONG/SEVERE
STORMS HAVE DEVELOPED IN ADVANCE OF THE SYSTEM FROM WRN INTO NRN MT.
A FAVORABLE THERMODYNAMIC PATTERN IS SUPPORTIVE OF INCREASING
SEVERE THREAT THROUGH THE EVENING AS AMPLE LOW LEVEL MOISTURE
/SURFACE DEWPOINTS IN THE 50S/ COUPLED WITH SUFFICIENT HEATING IS
LOCATED ALONG THE NRN PERIPHERY OF STEEP MID LEVEL LAPSE
RATES...ENHANCED BY STRONG DIRECTIONAL/SPEED SHEAR IN THE LOW-MID
LEVELS. STORMS ARE EXPECTED TO GRADUALLY ORGANIZE INTO BOWING LINE
SEGMENTS ACROSS CENTRAL/ERN MT POSSIBLY SPREADING INTO ND TONIGHT.
THIS IS SUPPORTED BY MORNING CONVECTION-ALLOWING MODEL GUIDANCE
INCLUDING THE LATEST HRRR THAT INDICATE POTENTIAL FOR SIGNIFICANT
SEVERE WIND GUSTS AS A COMPOSITE COLD POOL GROWS UPSCALE...AND THIS
HAS BEEN INCLUDED IN THE SEVERE WIND GRAPHICS FROM MT INTO WRN ND.
OTHERWISE...MINOR ADJUSTMENTS HAVE BEEN MADE TO EXTEND THE SEVERE
RISK AREA SLIGHTLY FARTHER WEST IN MT BASED ON CURRENT STORM
INITIATION REGIONS.

...WY/SD/NEB/IA...
CONSENSUS OF CONVECTION-ALLOWING MODELS CONTINUES TO SUPPORT
DEVELOPMENT OF STRONG/SEVERE STORMS MOVING ACROSS THE NRN NEB/SRN SD
REGION LATE THIS AFTERNOON AND TONIGHT...IN ASSOCIATION WITH A SHORT
WAVE TROUGH EVIDENT IN WATER VAPOR IMAGERY MOVING INTO THE HIGH
PLAINS. THE ENVIRONMENT IS CHARACTERIZED BY SUFFICIENT INSTABILITY
/MLCAPE 1500-2500 J PER KG/ ALONG THE SRN EDGE OF STRONGER WINDS
ALOFT AND VERTICAL SHEAR. TO BETTER INDICATE THE POTENTIAL FOR A
CORRIDOR OF SEVERE STORMS WITH ENHANCED DAMAGING WIND POTENTIAL
ASSOCIATED WITH A BOWING LINEAR MCS...A 30% WIND PROBABILITY AREA
HAS BEEN ADDED FROM NRN NEB/SRN SD EWD INTO WRN IA/SWRN MN FOR
TONIGHT. SEE MCD 1347 FOR MORE DETAILS.

...EXTREME SERN LOWER MI INTO NRN OH...
THE SMALL SLIGHT RISK THREAT AREA HAS BEEN ADJUSTED EWD TO BE
CO-LOCATED WITH A NARROW INSTABILITY AXIS COINCIDENT WITH A
THUNDERSTORM BAND EXTENDING FROM SERN LOWER MI INTO NORTH CENTRAL
OHIO. ISOLATED DAMAGING WIND GUSTS WILL BE THE MOST LIKELY THREAT
BEFORE STORMS DIMINISH LATER THIS EVENING.

...MID ATLANTIC REGION...
A FEW STORMS MAY PERSIST INTO THIS EVENING IS ASSOCIATION WITH AN
UPPER LOW MOVING SLOWLY EWD ACROSS PA. BRIEF GUSTY WINDS WILL BE
POSSIBLE WITH STRONGER CELLS.

..WEISS.. 07/08/2013

.PREV DISCUSSION... /ISSUED 1113 AM CDT MON JUL 08 2013/

...MT/ND...
WATER VAPOR LOOPS SHOW A WELL-DEFINED AND PROGRESSIVE UPPER TROUGH
OVER EASTERN WA/ORE. THIS FEATURE...ALONG WITH A LEADING VORT MAX
OVER NORTHERN ID WILL TRACK EASTWARD ACROSS THE NORTHERN ROCKIES
TODAY. THIS SHOULD SET THE STAGE FOR AN ACTIVE AFTERNOON/EVENING OF
SEVERE STORMS OVER PARTS OF MT.

THUNDERSTORMS ARE ONGOING OVER NORTHWEST MT AHEAD OF THE LEAD
SHORTWAVE...AND WILL LIKELY PERSIST FOR SEVERAL HOURS AS THEY TRACK
EAST-NORTHEASTWARD ALONG/SOUTH OF THE CANADIAN BORDER. THE AIR MASS
AHEAD OF THE STORMS IS NOT PARTICULARLY UNSTABLE...SO THE SEVERE
THREAT IS LIKELY TO BE LIMITED. NEVERTHELESS...ISOLATED
STRONG/SEVERE STORMS WITH HAIL AND GUSTY WINDS WILL BE POSSIBLE.

A MORE SUBSTANTIAL RISK OF SEVERE WEATHER WILL EVOLVE LATER THIS
AFTERNOON AS THE PRIMARY UPPER TROUGH APPROACHES FROM THE WEST.
STORMS ARE EXPECTED TO DEVELOP OVER WEST/WEST-CENTRAL MT AND TRACK
EASTWARD THROUGH MUCH OF THE EVENING. SEVERAL OVERNIGHT AND 12Z
MODEL SOLUTIONS SUGGEST SUPERCELLS WILL ORGANIZE INTO BOWING LINE
SEGMENTS ACROSS THIS AREA. HIGH LCL HEIGHTS SHOULD LIMIT THE
TORNADO RISK...BUT VERY LARGE HAIL AND SWATHS OF WIDESPREAD DAMAGING
WINDS ARE POSSIBLE. STORMS MAY MAINTAIN SEVERE INTENSITY AS FAR
EAST AS WESTERN ND LATE TONIGHT.

...WY/SD/NEB/IA...
ANOTHER SHORTWAVE TROUGH IS INDICATED IN WATER VAPOR IMAGERY OVER
SOUTHERN WY. THIS SYSTEM WILL APPROACH THE HIGH PLAINS OF WESTERN
SD/NEB TODAY FOSTERING THUNDERSTORM DEVELOPMENT. SOUTHEASTERLY LOW
LEVEL WINDS IN THIS REGION WILL MAINTAIN DEWPOINTS IN THE
60S...WHICH ALONG WITH STEEP LAPSE RATES AND POCKETS OF STRONG
AFTERNOON HEATING WILL RESULT IN MODERATE MLCAPE. IT IS UNCLEAR
WHETHER PRIMARY INITIATION WILL BE ON THE WEST EDGE OF THE DEEPER
MOISTURE IN EASTERN WY...OVER PERHAPS ASSOCIATED WITH THE ONGOING
CONVECTION OVER SD. REGARDLESS...VERTICAL SHEAR IS FAVORABLE FOR
SUPERCELL STRUCTURES CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS.
THESE STORMS MAY ORGANIZE INTO AN MCS AND PERSIST MUCH OF THE NIGHT
ACROSS PARTS OF NEB/SD INTO IA.

...IND/OH/LWR MI...
THE REMNANTS OF AN OVERNIGHT MCS ARE TRACKING EAST-SOUTHEASTWARD
ACROSS PARTS OF LOWER MI/NORTHWEST IND/CENTRAL IL. STRONG HEATING
IS OCCURRING AHEAD OF THIS ACTIVITY...WHERE DEWPOINTS ARE IN THE
UPPER 60S AND MLCAPE VALUES SHOULD REACH 2000+ J/KG. WHILE THE
TIMING IS UNCERTAIN...THE POTENTIAL EXISTS FOR REDEVELOPMENT OF
INTENSE STORMS ALONG THE REMNANT OUTFLOW BOUNDARY. LOCALLY DAMAGING
WINDS WOULD BE THE MAIN THREAT. SEVERAL 12Z MODEL SOLUTIONS SUPPORT
THIS SCENARIO.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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.