Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 011619
SWODY1
SPC AC 011617

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1117 AM CDT SAT AUG 01 2015

VALID 011630Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SD/MN/WI...

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF THE MIDWEST...

...THERE IS A MRGL RISK OF SVR TSTMS OVER PARTS OF NEW ENGLAND...

...SUMMARY...
SEVERE THUNDERSTORMS MAY DEVELOP THIS AFTERNOON AND MOVE
SOUTHEASTWARD THIS EVENING ACROSS PARTS OF THE NORTH-CENTRAL PLAINS
AND UPPER MIDWEST...OFFERING DAMAGING WIND AND SEVERE HAIL
POTENTIAL. A FEW THUNDERSTORMS MAY PRODUCE HAIL AND DAMAGING GUSTS
NEAR SEVERE LEVELS IN NEW ENGLAND.

...MIDWEST STATES...
A BROAD UPPER RIDGE IS PRESENT TODAY OVER THE WESTERN STATES...WITH
CYCLONIC FLOW ALOFT FROM THE NORTHERN PLAINS ACROSS THE NORTHEAST
STATES.  WATER VAPOR LOOP SHOWS A SUBTLE SHORTWAVE TROUGH MOVING
ACROSS EASTERN MT/WESTERN ND.  THIS FEATURE WILL HELP TO INITIATE
ISOLATED AFTERNOON THUNDERSTORMS OVER PARTS OF EASTERN ND/SD AND
CENTRAL/SOUTHERN MN.  THOSE STORMS THAT FORM WILL TRACK
EAST-SOUTHEASTWARD THROUGH THE EVENING...WHERE MODERATE CAPE VALUES
AND FAVORABLE VERTICAL SHEAR WILL SUPPORT SUPERCELL/BOWING STORM
STRUCTURES.  HAIL AND DAMAGING WINDS WILL BE POSSIBLE IN THE
STRONGER CORES.

FARTHER SOUTH...CONSIDERABLE UNCERTAINTY EXISTS REGARDING THE
COVERAGE AND LOCATION OF STRONG CONVECTION.  OVERNIGHT CONVECTION
OVER EASTERN NEB HAS CREATED WIDESPREAD CLOUDS THAT WILL REDUCE
HEATING/DESTABILIZATION AND LESSEN THE PROBABILITY OF CONVECTIVE
INITIATION.  12Z MODEL SOLUTIONS SHOW LITTLE CONSISTENCY ACROSS MUCH
OF NEB/IA AND NORTHERN IL.  THEREFORE...HAVE BACKED OFF TO MRGL
CATEGORY FOR THIS REGION AND WILL RE-EVALUATE IN LATER UPDATES.

...NEW ENGLAND...
SATELLITE/RADAR DATA SHOW SCATTERED THUNDERSTORMS DEVELOPING OVER
PARTS OF EASTERN QUEBEC AND NORTHERN NEW ENGLAND.  THIS ACTIVITY
WILL AFFECT PARTS OF VT/NH/ME THROUGH THE MID AFTERNOON BEFORE
MOVING EASTWARD AND AWAY FROM THE US.  FORECAST SOUNDINGS SHOW
CONSIDERABLE EFFECTIVE SHEAR FOR FAST-MOVING STORMS CAPABLE OF GUSTY
WINDS.  HOWEVER...THERMODYNAMIC PROFILES ARE RATHER BENIGN WITH MID
LEVEL LAPSE RATES ONLY AROUND 6 C/KM AND MLCAPE VALUES OF 500-800
J/KG.  ISOLATED SEVERE STORMS ARE POSSIBLE WITH GUSTY WINDS AND
HAIL...BUT OVERALL THREAT APPEARS MARGINAL.

..HART/PICCA.. 08/01/2015




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