Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 301942
SWODY1
SPC AC 301940

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT SUN AUG 30 2015

VALID 302000Z - 311200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF MT...

...SUMMARY...
ISOLATED SEVERE STORMS WITH WIND AND HAIL MAY DEVELOP ACROSS PARTS
OF MONTANA THIS AFTERNOON INTO MID-EVENING.

...DISCUSSION...
WITH CURRENT FORECAST REASONING ON TRACK...NO SUBSTANTIAL CHANGES TO
OUTLOOK AREAS APPEAR REQUIRED THIS FORECAST.

..GOSS.. 08/30/2015

.PREV DISCUSSION... /ISSUED 1130 AM CDT SUN AUG 30 2015/

...SYNOPSIS...
MORNING SATELLITE IMAGERY DEPICTS A LEAD SHORTWAVE TROUGH MOVING
THROUGH CNTRL MT WITH A HARD EDGE TO THE CLOUD DECK SUGGESTING
STRONG SUBSIDENCE BEHIND THE WAVE. ANOTHER SHORTWAVE TROUGH --
EMBEDDED WITHIN THE LARGER MEAN TROUGH EXTENDING ACROSS MUCH OF WRN
CANADA AND INTO THE NW CONUS -- IS MOVING THROUGH WRN WA WITH
CONTINUED EWD PROGRESSION INTO THE NRN ROCKIES/NRN HIGH PLAINS
ANTICIPATED. FARTHER E...BROAD UPPER TROUGH EXTENDS ACROSS MUCH OF
ERN CONUS WITH SEVERAL WEAK EMBEDDED VORTICITY MAXIMA. A
WELL-DEFINED MID-LEVEL VORT MAX CURRENTLY MOVING NEWD INTO SE AL/SW
GA WILL CONTINUE NEWD ACROSS THE CAROLINA PIEDMONT.

15Z SURFACE ANALYSIS PLACES THE PRIMARY BAROCLINIC ZONE IN MT FROM
JUST E OF GGW SWWD THROUGH BIL AND INTO WRN WY...SLIGHTLY AHEAD OF
THE CLEARING LINE OBSERVED ON VISIBLE SATELLITE IMAGERY. WEAK
FRONTAL BOUNDARY ALSO EXTENDS FROM SW TX NEWD THROUGH THE MID MO
VALLEY AND INTO LWR MI.

...CNTRL MT...
CLEARING TREND BEHIND THE MAIN WAVE IS EXPECTED TO CONTINUE AS THE
WAVE PERSISTS ACROSS CNTRL MT...WHICH WOULD ALLOW FOR AT LEAST
MODEST HEATING IN ITS WAKE. HOWEVER...THE PRESENCE OF THE UPSTREAM
SHORTWAVE TROUGH CASTS SOME DOUBT ONTO JUST HOW CLEAR THE SKIES GET.
REGARDLESS...FILTERED SUNSHINE COUPLED WITH DOWNSLOPING SWLY WINDS
SHOULD RESULT IN GOOD BOUNDARY LAYER MIXING AND...WHEN COUPLED WITH
STEEP MID-LEVEL LAPSE RATES AND MODEST MOISTURE...SOME INSTABILITY.
LIFT ASSOCIATED WITH THE APPROACHING SHORTWAVE TROUGH WILL PROVIDE
THE IMPETUS FOR TSTM DEVELOPMENT WITH GUIDANCE IN GOOD AGREEMENT
THAT TSTM ACTIVITY WILL BEGIN AROUND 21Z AND PERSIST ACROSS CNTRL MT
THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING. STRONG SWLY FLOW
ALOFT /50-60 KT AT 500 MB/ WILL RESULT IN STRONG SHEAR PROFILES AND
LONG HODOGRAPHS...SUPPORTING TSTM ORGANIZATION AND AT LEAST SOME
POTENTIAL FOR HIGH-BASED SUPERCELLS CAPABLE OF HAIL AND GUSTY WINDS.

...FL...COASTAL CAROLINAS...
TSTM ACTIVITY IS EXPECTED ACROSS MOST OF THE AREA AS THE MID-LEVEL
LOW INTERACTS WITH A VERY MOIST ENVIRONMENT. CLOUDINESS AND
GENERALLY MOIST PROFILES WILL KEEP INSTABILITY LOW WITH A RESULTING
LOW THREAT OF SVR. SHEAR WILL LIKELY BE ENHANCED SOMEWHAT FROM THE
CNTRL FL PANHANDLE NEWD THROUGH THE COASTAL CAROLINAS BUT MOST
RECENT GUIDANCE AS WELL AS THE RECENT CONVECTIVE BURST JUST OFF THE
NE FL COAST SUGGEST THE WARM SECTOR WILL REMAIN OFFSHORE...KEEPING
THE SEVERE THREAT LOW.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.