Severe Storm Outlook Narrative (AC)
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000
ACUS02 KWNS 191733
SWODY2
SPC AC 191732

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 PM CDT FRI SEP 19 2014

VALID 201200Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN IL INTO SWRN LOWER
MI...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF NRN MN...NWRN WI
AND FAR ERN ND...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED SATURDAY FROM NORTHERN
ILLINOIS INTO SOUTHWESTERN LOWER MICHIGAN. LARGE HAIL AND STRONG
WINDS WILL BE POSSIBLE. SEVERE WIND AND MARGINALLY SEVERE HAIL IS
ALSO LIKELY ACROSS MUCH OF NORTHERN MINNESOTA AND VICINITY. A LOWER
THREAT OF SEVERE WEATHER EXISTS ACROSS NEVADA AND WESTERN UTAH.

...SYNOPSIS...
A BROAD AREA OF CYCLONIC FLOW ALOFT WILL EXTEND FROM THE NRN PLAINS
EWD INTO ERN CANADA WITH A LEADING SHORTWAVE DISTURBANCE FROM THE
UPPER MS VALLEY INTO THE UPPER GREAT LAKES DURING THE DAY. A SFC
TROUGH WILL TRAIL FROM A NEWD-MOVING SFC LOW...EXTENDING ROUGHLY
FROM ERN UPPER MI INTO NRN MO BY 00Z. SWLY FLOW AHEAD OF THIS TROUGH
WILL RESULT IN A MOIST AND UNSTABLE AIR MASS CAPABLE OF SUPPORTING
SEVERE STORMS.

TO THE NW...A POTENT SHORTWAVE TROUGH WILL DIVE SEWD OUT OF CANADA
WITH THE LEFT-FRONT QUADRANT OF A CYCLONICALLY-CURVED JET MAX MOVING
FORM ERN ND INTO CNTRL MN DURING THE DAY. ALTHOUGH INSTABILITY WILL
BE WEAK...VERY STRONG FORCING WITH THIS COLD FRONT MAY RESULT IN
SEVERE THUNDERSTORMS BY EARLY AFTERNOON.

ELSEWHERE...A FEW STRONG STORMS CAPABLE OF SMALL HAIL AND GUSTY
WINDS ARE LIKELY OVER NV...BUT MOST LIKELY NON-SEVERE IN NATURE.

...LOWER MI INTO NRN IL...
EARLY STORMS MAY BE ONGOING ACROSS MUCH OF MI WITHIN A PLUME OF
HIGHER-THETAE AIR AND IN A ZONE OF INCREASING DIFFERENTIAL
DIVERGENCE NEAR ENTRANCE REGION OF UPPER JET. SOME OF THIS ACTIVITY
COULD CONTAIN HAIL NEAR SEVERE LEVELS. LATER IN THE DAY...HEATING
WILL OCCUR UPSTREAM AND ALSO S OF ANY OUTFLOW BOUNDARY THAT MIGHT
HAVE BEEN PRODUCED BY EARLIER STORMS. ALTHOUGH FORCING FOR ASCENT
WILL BE WEAK BY THIS POINT...THE COOL PROFILES ALOFT AND HEATING
SHOULD EASILY MIX OUT ANY CAPPING INVERSION WITH MODERATE
INSTABILITY DEVELOPING. ISOLATED TO SCATTERED SEVERE STORMS CAPABLE
OF LARGE HAIL AND A FEW SMALL BOWS WITH WIND DAMAGE APPEAR
LIKELY...DEVELOPING ON OUTFLOW BOUNDARIES OR OTHER AREAS OF
LOW-LEVEL CONVERGENCE. RIGHT-MOVING CELLS WILL EXPERIENCE GREATER
LEVELS OF SRH AND WITH A TORNADO OR TWO POSSIBLE AS WELL CONDITIONAL
ON SUPERCELLULAR STORM MODE.

...ERN ND INTO MN AND NWRN WI...
HEATING WILL OCCUR AHEAD OF A VERY INTENSE COLD FRONT WHICH WILL BE
OVER ND AT 18Z. THIS FRONT WILL SURGE SEWD...WHERE MUCAPE ON THE
ORDER OF 500 J/KG IS EXPECTED TO DEVELOP. LONG HODOGRAPHS SUGGEST A
FORWARD-PROPAGATING LINE OF STORMS CAPABLE OF WIND DAMAGE...AND
LARGE AMOUNTS OF SMALL TO MARGINALLY SEVERE HAIL GIVEN VERY COOL
TEMPERATURES ALOFT AND FAVORABLE TIME OF DAY.

...NERN KS INTO NRN MO...
MODERATE INSTABILITY WILL DEVELOP AHEAD OF A WEAK LOW PRESSURE
TROUGH. SHEAR PROFILES WILL BE WEAK...BUT ANY ISOLATED ACTIVITY THAT
DEVELOPS MAY PRODUCE SOME HAIL DURING THE PEAK HEATING HOURS.

..JEWELL.. 09/19/2014




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