Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS02 KWNS 301731
SWODY2
SPC AC 301730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT JUL 30 2016

VALID 311200Z - 011200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE NORTHERN PLAINS...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PORTIONS OF THE CENTRAL
PLAINS AND LOWER MO VALLEY...

...SUMMARY...
SCATTERED THUNDERSTORMS...SOME SEVERE...ARE EXPECTED TO DEVELOP
DURING THE LATE AFTERNOON ACROSS THE WESTERN DAKOTAS.  STRONG STORMS
MAY ALSO DEVELOP ACROSS PORTIONS OF THE CENTRAL PLAINS AND LOWER
MISSOURI VALLEY.

...NRN PLAINS...
MODEL CONSENSUS MAINTAINS A NORTHEAST TRACK OF A SHORTWAVE TROUGH
FROM BRITISH COLUMBIA AND WA TO SOUTHERN SASKATCHEWAN THIS FORECAST
PERIOD...AS A 50-60-KT 500-MB SPEED MAX REACHES SOUTHEAST
SASKATCHEWAN AND NORTHWEST ND BY 01/12Z.  THIS WILL RESULT IN THE
STRONGEST LARGE-SCALE ASCENT REMAINING NORTH OF THE INTERNATIONAL
BORDER...WHILE HEIGHTS RISE DURING THE FIRST HALF OF THE PERIOD
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST.  A LEE TROUGH/DRY LINE
IS EXPECTED TO EXTEND N-S FROM SOUTHEAST SASKATCHEWAN THROUGH THE
FAR WESTERN DAKOTAS TO THE NEB PANHANDLE...AND WILL BE THE PRIMARY
FOCUS FOR THUNDERSTORM DEVELOPMENT SUNDAY AFTERNOON.  A TRAILING
COLD FRONT...ATTENDANT TO THE SHORTWAVE TROUGH...IS EXPECTED TO
ADVANCE INTO NORTHEAST MT SUNDAY EVENING AND INTO WESTERN ND BY 12Z
MONDAY.  A MOIST AIR MASS COUPLED WITH STRONG SURFACE HEATING
BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES WILL RESULT IN MUCAPE
OF 2000-3000 J/KG.  DESPITE LARGE-SCALE HEIGHT RISES ACROSS THE
NORTHERN PLAINS INTO SUNDAY AFTERNOON...WEAK MIDLEVEL IMPULSES
SPREADING ACROSS THE DRY LINE DURING PEAK HEATING SHOULD PROVE
FAVORABLE IN SUPPORTING STORM DEVELOPMENT.  HOWEVER...THE OVERALL
WEAK FORCING ALOFT SUGGESTS COVERAGE OF STRONG TO SEVERE STORMS
SHOULD BE ISOLATED AND THUS WILL MAINTAIN A MARGINAL SEVERE RISK
ACROSS THIS REGION.  INITIAL STORMS SHOULD HAVE HIGH CLOUD BASES DUE
TO STRONG SURFACE HEATING...WHILE EFFECTIVE BULK SHEAR OF 30-40 KT
SUGGESTS SUPERCELLS WILL BE POSSIBLE.  GUSTY WINDS AND PERHAPS SOME
HAIL COULD ACCOMPANY THIS ACTIVITY AS IT PROPAGATES INTO CENTRAL ND
THROUGH LATE SUNDAY EVENING.

...CENTRAL PLAINS/LOWER MO VALLEY...
AN MCS SHOULD BE ONGOING AT 12Z SUNDAY...GIVEN STRONG LOW-LEVEL WAA
WITHIN THE NOSE OF A SOUTHWESTERLY LLJ EXTENDING INTO EASTERN
NEB/NORTHWEST MO.  EARLY ACTIVITY COULD STILL BE STRONG TO
SEVERE...THOUGH CONVECTION MAY WEAKEN INTENSITY AS IT SPREADS
DOWNSTREAM INTO NORTHERN MO SUNDAY MORNING/EARLY AFTERNOON.  MODELS
MAINTAIN THE DEVELOPMENT OF ANOTHER STRONG NOCTURNAL LLJ INTO
PORTIONS OF THE CENTRAL PLAINS TO LOWER MO VALLEY TO SUPPORT ANOTHER
MCS DEVELOPMENT SUNDAY EVENING THROUGH SUNDAY NIGHT.  MODERATE
ELEVATED INSTABILITY ON THE EASTERN EXTENT OF STEEP MIDLEVEL LAPSE
RATES AND STRONG BULK SHEAR SUGGESTS SOME OF THESE STORMS COULD BE
STRONG TO SEVERE WITH HAIL AND WIND THE PRIMARY SEVERE HAZARDS.
GIVEN THE GREATEST THREATS ARE EXPECTED TO BE DURING THE EARLY
MORNING AND LATER SUNDAY EVENING/NIGHT...THIS OUTLOOK WILL MAINTAIN
LOW SEVERE PROBABILITIES.

...AZ...
STORMS ARE EXPECTED ACROSS THIS REGION ON SUNDAY...THOUGH WEAK
MIDLEVEL WINDS PROVIDE TOO MUCH UNCERTAINTY FOR A SEVERE WEATHER
THREAT TO INCLUDE SEVERE PROBABILITIES WITH THIS OUTLOOK ISSUANCE.

..PETERS.. 07/30/2016

$$



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