Severe Storm Outlook Narrative (AC)
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ACUS03 KWNS 010723
SWODY3
SPC AC 010723

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0223 AM CDT SAT OCT 01 2016

VALID 031200Z - 041200Z

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE NEB SANDHILLS
NORTHWARD INTO THE NORTHERN PLAINS...

...SUMMARY...
ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE OVER PARTS OF
WESTERN NEBRASKA NORTHWARD INTO SOUTHEASTERN MONTANA AND THE WESTERN
DAKOTAS MONDAY AFTERNOON AND EVENING.

...SYNOPSIS...
A VIGOROUS MID-LEVEL DISTURBANCE WILL ROTATE THROUGH THE BASE OF A
LARGER-SCALE WESTERN U.S. TROUGH AND MOVE FROM UT INTO SOUTHEASTERN
MT DURING THE DAY AND EVOLVE INTO A CLOSED H5 LOW.  A STRONG
CYCLONIC FLOW REGIME WILL ENCOMPASS MUCH OF THE SOUTHWESTERN U.S.
INTO THE GREAT PLAINS.  IN THE LOW LEVELS...A COLD FRONT WILL EXTEND
SOUTHWARD FROM A DEEPENING SURFACE LOW OVER EASTERN MT/WESTERN ND.

...WESTERN NEB NORTHWARD INTO THE DAKOTAS AND SOUTHEASTERN MT...
STRONG LOW-LEVEL SOUTHERLY FLOW ONGOING EARLY MONDAY OVER THE
CENTRAL AND NORTHERN PLAINS WILL BE MAINTAINED AS AN 80-KT H5 SPEED
MAX APPROACHES AND ASSOCIATED HEIGHT FALLS /IN EXCESS OF 60 M PER 12
HR/ OVERSPREAD THE REGION.  MODELS SHOW A NARROW CORRIDOR OF MID TO
POSSIBLY UPPER 50S DEWPOINTS FROM THE SANDHILLS NORTHWARD INTO THE
WESTERN DAKOTAS WHICH WILL LIKELY CONTRIBUTE TO WEAK-MODERATE
BUOYANCY 250-1250 J/KG MLCAPE.  A CAPPING INVERSION WILL BECOME MORE
PROMINENT WITH SOUTHWARD EXTENT AND LIKELY DELAY --IN SOME CASES ACT
TO INHIBIT-- STORM DEVELOPMENT DURING THE AFTERNOON/EARLY EVENING.
NONETHELESS...IT APPEARS ISOLATED TO SCATTERED THUNDERSTORMS WILL
DEVELOP INITIALLY NEAR THE SURFACE LOW AND BOUNDARY.  FORECAST
SOUNDINGS SHOW STRENGTHENING AND VEERING WIND PROFILES WITH HEIGHT
SUPPORTING THE RISK FOR ORGANIZED STORM STRUCTURES.  LESSENING
INSTABILITY AFTER DARK WILL LIKELY LEAD TO A WEAKENING IN STORMS AS
A STRONG LOW-LEVEL WAA REGIME SHIFTS EASTWARD AND STRENGTHENS OVER
THE CENTRAL AND NORTH-CENTRAL PLAINS DURING THE OVERNIGHT HOURS.

..SMITH.. 10/01/2016

$$



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