Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 010504
SWODY1
SPC AC 010502

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1202 AM CDT WED OCT 01 2014

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN AND NRN KS...SRN AND
ERN NEB...WRN AND CNTRL MO...FAR NERN OK...

...SUMMARY...
SEVERE THUNDERSTORMS CAPABLE OF VERY LARGE HAIL...LOCALIZED DAMAGING
WINDS AND A TORNADO OR TWO ARE LIKELY ACROSS MUCH OF EASTERN KANSAS
INTO WESTERN MISSOURI AND FAR NORTHEASTERN OKLAHOMA DURING THE DAY.
OTHER STRONG TO SEVERE STORMS WITH HAIL AND WIND WILL BE POSSIBLE
ACROSS CENTRAL NEBRASKA DURING THE LATE AFTERNOON...AS WELL AS FROM
EASTERN COLORADO INTO NORTHERN KANSAS AND SOUTHERN NEBRASKA
OVERNIGHT.

...SYNOPSIS...
A LARGE AREA OF CYCLONIC FLOW ALOFT WILL EXTEND FROM THE ROCKIES
INTO THE PLAINS WITH A BROAD AREA OF LOW PRESSURE FROM SWRN KS INTO
NWRN TX. A LEADING SHORTWAVE TROUGH WILL AFFECT MUCH OF ERN KS INTO
MO EARLY IN THE DAY AND WILL RESULT IN ONGOING AREAS OF STORMS WHICH
WILL COMPLICATE THE FORECAST LATER ON.

BEHIND THIS DISTURBANCE...SWLY FLOW ALOFT WILL STRENGTHEN ALTHOUGH
HEIGHT TENDENCIES WILL BE NEUTRAL. STILL...COOL TEMPERATURES ALOFT
AND THE PRESENCE OF DEWPOINTS WELL INTO THE 60S E OF A DRYLINE WILL
RESULT IN AMPLE INSTABILITY FOR STRONG TO SEVERE STORMS WITH
MULTIPLE POTENTIAL AREAS EXTENDING FROM CO INTO MO THROUGH THE
PERIOD.

...ERN KS INTO WRN MO...NERN OK...
SCATTERED THUNDERSTORMS WILL BE ONGOING ACROSS ERN KS INTO MO IN
ASSOCIATION WITH THE LEADING SHORTWAVE TROUGH AND IN A ZONE OF
PERSISTENT LOW-LEVEL WARM AIR ADVECTION. SOME HAIL IS POSSIBLE WITH
THIS EARLY ACTIVITY. HOWEVER...THE GREATEST THREAT WILL BE DURING
THE AFTERNOON AND EARLY EVENING WHEN HEATING NEAR THE WRN FRINGE OF
THE OUTFLOW/DIFFERENTIAL HEATING ZONE RESULTS IN STRONG INSTABILITY.
THE STRONGEST SHEAR PROFILES WILL ALSO EXIST IN THESE AREAS WITH
20-25 KT 850 MB FLOW ATOP S/SELY SURFACE WINDS NEAR THE BOUNDARY
RESULTING IN EFFECTIVE SRH POTENTIALLY ON THE ORDER OF 200-300
M2/S2. SUPERCELLS CAPABLE OF VERY LARGE HAIL ARE LIKELY...AND A
COUPLE TORNADOES MAY ALSO OCCUR DEPENDING ON HOW THE LOW-LEVEL
BOUNDARY SITUATION DEVELOPS DURING THE DAY.

FARTHER E ACROSS CNTRL MO...EARLY STORMS THAT FORM OVER ERN KS/WRN
MO MAY INCREASE IN INTENSITY AND EVOLVE INTO A DAMAGING WIND THREAT.
VEERING LOW-LEVEL WINDS FURTHER SUGGEST THAT EVEN IF THE STORM MODE
IS LINEAR...EMBEDDED AREAS OF ROTATION MAY EXIST.

...CNTRL/ERN NEB DURING THE DAY...
A WEAK LOW-PRESSURE TROUGH WILL BE NEARLY STATIONARY ACROSS CNTRL
NEB DURING THE DAY. STRONG HEATING AND STEEP LAPSE RATE PROFILES
WILL LEAD TO AN UNCAPPED ATMOSPHERE WITH ISOLATED STORMS LIKELY.
LOW-LEVEL WINDS WILL BE WEAK BUT DEEP LAYER SHEAR WILL BE SUFFICIENT
FOR A FEW SUPERCELLS CAPABLE OF LARGE HAIL.

...ERN CO LATE AFTERNOON INTO KS AND NEB OVERNIGHT...
HIGH-BASED THUNDERSTORMS ARE EXPECTED TO FORM ALONG A SURGING COLD
FRONT ACROSS CENTRAL CO BY EARLY AFTERNOON...THEN ARE EXPECTED TO
GRADUALLY GROW UPSCALE AS THE FRONT EMERGES INTO THE PLAINS. STRONG
WIND GUSTS AND/OR SMALL HAIL WILL BE LIKELY INITIALLY...WITH A
SEVERE THREAT POSSIBLY DEVELOPING DURING THE EVENING AND OVERNIGHT
AS THE STRONG FORCING INTERACTS WITH STRONGER INSTABILITY AND
MOISTURE OVER NEB AND KS. DAMAGING WINDS AND HAIL WILL BE POSSIBLE
WITH ONLY A SHALLOW SURFACE STABLE LAYER IN PLACE.

...WRN OK INTO NWRN TX...
A CONDITIONAL THREAT OF HAIL WILL EXIST DURING THE LATE AFTERNOON
NEAR A RETREATING DRYLINE. HEATING WILL BE STRONG...AND A NARROW
ZONE NEAR THE DRYLINE SHOULD BECOME UNCAPPED. WHILE CONVERGENCE IS
WEAK...ISOLATED STORMS CANNOT BE RULED OUT. IF THEY FORM...THEY WILL
LIKELY BE CELLULAR WITH A HAIL THREAT.

..JEWELL/ROGERS.. 10/01/2014



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