Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 250537
SWODY1
SPC AC 250536

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1236 AM CDT SAT OCT 25 2014

VALID 251200Z - 261200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF NORTHERN CA AND
SOUTHWEST OREGON...

...SUMMARY...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS NORTHERN
CALIFORNIA INTO SOUTHWEST OREGON SATURDAY AFTERNOON.  A FEW STORMS
MAY BECOME CAPABLE OF PRODUCING A WEAK/BRIEF TORNADO ACROSS THIS
REGION.  SCATTERED THUNDERSTORMS WILL ALSO DEVELOP ACROSS UPSTATE
NEW YORK INTO PORTIONS OF NORTHERN NEW ENGLAND.

...PACIFIC COAST...

LATE EVENING SATELLITE IMAGERY DEPICTS A WELL-DEFINED MID-LEVEL
CIRCULATION OFF THE NRN CA COAST...CENTERED NEAR 39N/130W.  THIS
FEATURE IS LIFTING NEWD TOWARD THE OREGON COAST AND SHOULD MOVE
INLAND AFTER 18Z AS 80-100KT 500MB SPEED MAX TRANSLATES INTO ERN
OREGON AND WEAKENS.  LATEST GUIDANCE SUGGESTS 12HR MID-LEVEL HEIGHT
FALLS ON THE ORDER OF 150M SHOULD SPREAD ACROSS WRN OREGON INTO WA
DURING THE DAY.  WHILE STRONGEST LARGE-SCALE FORCING IS EXPECTED TO
FOCUS NORTH OF MRGL RISK REGION...SRN EXTENT OF LOW-LEVEL
CONVERGENCE SHOULD EXTEND INTO NRN CA WHERE SHEAR PROFILES WILL BE
MORE THAN ADEQUATE FOR SUSTAINING ORGANIZED UPDRAFTS.  PRIMARY
NEGATIVES ACROSS THIS REGION WILL BE MODEST LAPSE RATES/MEAGER
BUOYANCY WHICH SHOULD NEGATE UPDRAFT INTENSITY.  FORECAST SOUNDINGS
ACROSS NRN CA/SWRN OREGON SUGGEST SFC-BASED CONVECTION IS POSSIBLE
AND LONGER-LIVED UPDRAFTS COULD ROTATE...PERHAPS EVEN BRIEFLY
PRODUCING A FEW WEAK TORNADOES.

...NERN U.S...

FOCUSED AREA OF ASCENT WITHIN EXIT REGION OF STRONG MID-LEVEL JET
WILL SPREAD INTO UPSTATE NY AFTER 18Z.  WHILE MOISTURE IS QUITE
SPARSE ACROSS THIS REGION...AND 50F+ SFC DEW POINTS REMAIN 600MI
UPSTREAM OVER WI...SCT CONVECTION IS EXPECTED TO DEVELOP ALONG COLD
FRONT DURING THE LATE AFTERNOON AS LAPSE RATES STEEPEN WITHIN
COOLING MID-LEVEL PROFILE.  FORECAST SOUNDINGS ACROSS UPSTATE NY
SUGGEST SFC-BASED CONVECTION IS LIKELY DESPITE THE EXPECTED COOL SFC
TEMPERATURES.  IN FACT...CLOUD HEIGHTS COULD EXCEED 6KM AND
GRAUPEL/SMALL HAIL MAY ACCOMPANY MUCH OF THIS ACTIVITY.  GIVEN THE
EXPECTED STEEP LOW-LEVEL LAPSE RATES GUSTY WINDS MAY ALSO OCCUR WITH
THIS CONVECTION.

..DARROW/DEAN.. 10/25/2014




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