Severe Storm Outlook Narrative (AC)
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ACUS02 KWNS 211745
SWODY2
SPC AC 211744

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1244 PM CDT THU AUG 21 2014

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NORTHEAST CO...NORTHWEST
KS INTO NEBRASKA...

...SUMMARY...
SCATTERED STRONG TO SEVERE STORMS WILL BE POSSIBLE FROM NORTHEAST
COLORADO AND NORTHWEST KANSAS INTO NEBRASKA FRIDAY AFTERNOON AND
INTO FRIDAY EVENING AND OVERNIGHT ACROSS PORTIONS OF THE CENTRAL AND
NORTHERN PLAINS.  LARGE HAIL AND STRONG WIND GUSTS WILL BE THE
PRIMARY THREATS...THOUGH A TORNADO CANNOT BE RULED OUT IN THE
WESTERN EXTENT OF THE SLIGHT RISK AREA.  A FEW STRONG TO SEVERE
STORMS WILL BE POSSIBLE FROM IOWA TO THE OHIO VALLEY AND PERHAPS THE
CENTRAL APPALACHIAN MOUNTAINS.

...SYNOPSIS...
A SHORTWAVE TROUGH DIGGING SOUTHEAST TODAY ALONG THE BRITISH
COLUMBIA COAST WILL AMPLIFY INTO A LARGER SCALE TROUGH ON FRIDAY
ACROSS THE NRN INTERMOUNTAIN REGION AND GREAT BASIN. THE EVOLUTION
OF THIS SYSTEM INTO DAY 2 WILL FURTHER AID IN DISLODGING THE COMPACT
LOWER CO RIVER VALLEY CLOSED LOW ON FRIDAY.  THIS LOW WILL TRACK
NEWD FROM AZ...REACHING THE CENTRAL HIGH PLAINS BY LATE FRIDAY
NIGHT.  MEANWHILE...MODELS SUGGEST WEAKER IMPULSES WILL PRECEDE THE
AZ LOW...MOVING NEWD FROM THE SRN ROCKIES INTO ERN CO TO SD BY PEAK
HEATING FRIDAY AFTERNOON.  DOWNSTREAM...A STRONG RIDGE WILL BE
MAINTAINED FROM THE GULF OF MEXICO INTO THE SRN PLAINS AND LOWER-MID
MS VALLEY WITH HEIGHT RISES INTO THE GREAT LAKES.  AT THE
SURFACE...A FRONT BECOMING STATIONARY TODAY ACROSS ERN NEB TO NRN KS
SHOULD EXTEND FROM CENTRAL IA WSWWD INTO NWRN KS AND ERN CO AT 12Z
FRIDAY.  THIS BOUNDARY WILL SHIFT A LITTLE NWD INTO FRIDAY AFTERNOON
AS A WARM FRONT AND EXTEND FROM CENTRAL IA WWD THROUGH EAST CENTRAL
TO SWRN NEB INTO NERN CO.  A DEVELOPING LEE LOW IN ERN CO WILL TRACK
ALONG THIS BOUNDARY FRIDAY NIGHT INTO CENTRAL NEB.

...PORTIONS OF THE CENTRAL PLAINS...
SURFACE DEWPOINTS IN THE 60S ALONG THE WARM FRONT FRIDAY AFTERNOON
COMBINED WITH A PLUME OF MIDLEVEL LAPSE RATES AROUND OR GREATER THAN
7 C/KM AND SURFACE HEATING WILL RESULT IN A MODERATELY UNSTABLE
ENVIRONMENT.  FORECAST SOUNDINGS SUGGEST SURFACE BASED INHIBITION
SHOULD WEAKEN BY EARLY-MID AFTERNOON ACROSS NERN CO/NWRN KS AND SWRN
NEB SUPPORTING CONVECTIVE DEVELOPMENT FROM THE LEE LOW ENEWD ALONG
THE WARM FRONT.  DEEP LAYER ASCENT WILL INCREASE DUE TO CONVERGENCE
INVOF THESE SURFACE FEATURES AND ATTENDANT TO THE WEAK IMPULSES
TRACKING NEWD ACROSS THIS REGION SHOULD PROVE SUPPORTIVE FOR DEEP
CONVECTION.  DESPITE WEAKER LOW-LEVEL WINDS INTO THE
AFTERNOON...EFFECTIVE BULK SHEAR OF 30-40 KT ACROSS THE SLIGHT RISK
AREA SUGGESTS MULTICELLS AND SUPERCELLS CAN BE EXPECTED WITH LARGE
HAIL AND DAMAGING WIND GUSTS THE PRIMARY THREATS WITH THE INITIAL
STORM DEVELOPMENT.  A STRENGTHENING SLY LLJ INTO WRN/CENTRAL KS TO
SRN NEB SHOULD ENHANCE LOW-LEVEL SHEAR AND PERHAPS A TORNADO THREAT
EARLY FRIDAY EVENING.  FURTHER STRENGTHENING AND VEERING OF THE
LOW-LEVEL JET ACROSS THE CENTRAL PLAINS...INCREASING WAA...AND
RESIDUAL MODERATE INSTABILITY SUGGESTS STRONG-SEVERE STORMS COULD
PERSIST THROUGH THE EVENING AND SPREAD EWD ACROSS CENTRAL/ERN NEB
AND NWD INTO SD.  HAIL AND GUSTY WINDS WOULD BE A THREATS WITH THIS
ACTIVITY INTO THE OVERNIGHT PERIOD.

...OH VALLEY TO THE MID MS VALLEY...
TSTMS SHOULD BE ONGOING ACROSS PORTIONS OF THIS REGION AT THE START
OF DAY 2...WITH LINGERING CLOUD DEBRIS POTENTIALLY LIMITING
DESTABILIZATION.  HOWEVER...MODELS SUGGEST THE ENVIRONMENT SHOULD
BECOME MODERATELY UNSTABLE WITH THE POTENTIAL FOR A FEW STRONG TO
SEVERE STORMS FRIDAY AFTERNOON INTO THE EVENING.  HEIGHT RISES FROM
THE MID MS VALLEY TO THE GREAT LAKES WOULD SUGGEST PORTIONS OF THE
MIDWEST /ACROSS IL/ MAY HAVE A LIMITED TSTM COVERAGE.

..PETERS.. 08/21/2014




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