SPC Aug 8, 2016 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT MON AUG 08 2016

VALID 081200Z - 091200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM PORTIONS OF THE NORTHERN
PLAINS TO THE NEBRASKA PANHANDLE AND WESTWARD THROUGH NORTHERN WY
AND SOUTHERN MT...

...SUMMARY...
A FEW STRONG TO SEVERE STORMS WITH A THREAT OF DOWNBURST WINDS AND
LARGE HAIL WILL BE POSSIBLE FROM PORTIONS OF THE NORTHERN PLAINS
INTO THE NORTH-CENTRAL HIGH PLAINS.  STRONG WIND GUSTS SHOULD BE THE
PRIMARY THREAT WITH WESTWARD EXTENT FROM EASTERN WYOMING TO THE
SOUTHWEST MONTANA REGION.

...SYNOPSIS...
A CLOSED LOW SITUATED OVER THE WA COAST AND ATTENDANT TROUGH AXIS
EXTENDING SOUTH OFF THE NORTHERN CA COAST WILL SHIFT SLOWLY TO THE
EAST ACROSS THE PACIFIC NORTHWEST REGION THIS FORECAST PERIOD.  A
LEAD MIDLEVEL TROUGH...CURRENTLY MOVING THROUGH CENTRAL MT PER
MOISTURE-CHANNEL IMAGERY...IS EXPECTED TO TRACK EAST FROM SOUTHERN
SASKATCHEWAN INTO SOUTHERN MANITOBA.  THE STRONGEST BAND OF MIDLEVEL
WINDS IS EXPECTED TO EXTEND FROM THE SOUTHERN EXTENT OF THE WESTERN
U.S. TROUGH THROUGH ID TO MT/NORTHERN WY THROUGH ND TO NORTHERN MN
AND INTO NORTHERN ONTARIO.  A LOW-AMPLITUDE WAVE CURRENTLY TRACKING
SOUTHEAST FROM JAMES BAY WILL MOVE ACROSS MAINE THROUGH 09/00Z. 
OTHERWISE....HEIGHTS ARE EXPECTED TO RISE ACROSS THE NORTHEAST
STATES.  FARTHER SOUTH...WEAK 500-MB WINDS WILL PREVAIL FROM THE
SOUTHWESTERN STATES THROUGH THE CENTRAL AND SOUTHERN PLAINS TO THE
MIDDLE AND SOUTHERN ATLANTIC STATES.

...DAKOTAS...NORTH-CENTRAL HIGH PLAINS TO NORTHERN WY/SOUTHERN MT...
FORCING FOR ASCENT ATTENDANT TO THE SOUTHERN CANADA MIDLEVEL TROUGH
MAY GLANCE PORTIONS OF NORTH DAKOTA...WHILE SHORTWAVE RIDGING IS
EXPECTED FROM NORTHERN WY INTO EASTERN MT BETWEEN THIS LEAD TROUGH
AND AHEAD OF THE PACIFIC NORTHWEST TROUGH.  AT THE SURFACE...A FRONT
ATTENDANT TO THE SOUTHERN SASKATCHEWAN/MANITOBA MIDLEVEL TROUGH WILL
ADVANCE EAST ACROSS ND AND WESTERN SD...WHILE TENDING TO BECOME
STATIONARY FROM EAST-CENTRAL WY TO SOUTHWEST MT.  LOW-LEVEL MOISTURE
WILL SPREAD NORTH...WITH A RELATIVELY NARROW CORRIDOR OF HIGHER
SURFACE DEW POINTS /LOWER 60S/ ALONG AND AHEAD OF THE SURFACE FRONT.
THIS COMBINED WITH STEEP LAPSE RATES WILL CONTRIBUTE TO MODERATE
DESTABILIZATION /MUCAPE 1000-2000 J PER KG/ FROM THE DAKOTAS TO
CENTRAL HIGH PLAINS.  INSTABILITY WILL BE WEAKER WITH WESTWARD
EXTENT THROUGH NORTHERN WY AND SOUTHERN MT.

CAPPING IS EXPECTED TO HINDER CONVECTIVE DEVELOPMENT ALONG AND AHEAD
OF THE FRONT IN THE DAKOTAS...THOUGH WEAK FORCING ALOFT /ACROSS
MAINLY ND/ COULD PROVE SUFFICIENT FOR GREATER STORM DEVELOPMENT
ALONG THIS PORTION OF THE FRONT.  DEEP-LAYER SHEAR WILL BE STRONGEST
FROM THE NORTHERN INTERMOUNTAIN WEST THROUGH ND ATTENDANT TO THE
AFOREMENTIONED STRONGEST CORRIDOR OF MIDLEVEL WINDS.  DESPITE THE
FORECAST FOR FAVORABLE CAPE/SHEAR PARAMETER SPACE FOR ORGANIZED
SEVERE STORMS BY LATE AFTERNOON INTO THE EVENING ACROSS MAINLY
ND...THE CAPPING AND WEAKER FORCING FOR ASCENT MAINTAIN UNCERTAINTY
IN THE OVERALL COVERAGE OF STORMS.  THIS PRECLUDES THE INTRODUCTION
OF HIGHER SEVERE PROBABILITIES.  GIVEN THE STEEP MIDLEVEL LAPSE
RATES AND MODERATE INSTABILITY...ISOLATED STRONG WIND GUSTS AND HAIL
WILL BE THE PRIMARY THREATS ACROSS THE DAKOTAS TO THE NEB PANHANDLE.

MEANWHILE...STORM COVERAGE IS EXPECTED TO BE RELATIVELY LESS WITH
WESTWARD EXTENT IN VICINITY OF THE TRAILING FRONT THROUGH NORTHERN
WY AND SOUTHERN MT...GIVEN WEAK DESTABILIZATION.  A DEEPER BOUNDARY
LAYER AND STEEP LAPSE RATES ACROSS THE HIGH PLAINS TO SOUTHWEST MT
SUGGEST STORMS DEVELOPING IN THESE AREAS WILL HAVE STRONG WIND GUSTS
AS THE PRIMARY THREAT.

...SOUTHEAST STATES...
ALTHOUGH THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE INTO
THIS AFTERNOON WITHIN A MODERATELY UNSTABLE ENVIRONMENT...WEAK
MIDLEVEL LAPSE RATES AND WEAK EFFECTIVE SHEAR WILL PRECLUDE A
SEVERE-WEATHER THREAT.

..PETERS/KERR.. 08/08/2016

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