Winter Storm Warning 8, NWS Juneau, AK

610 
WWAK47 PAJK 191957
WSWAJK

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE JUNEAU AK
1057 AM AKST WED FEB 19 2014


AKZ026-192100-
/X.EXP.PAJK.WS.W.0008.000000T0000Z-140219T2000Z/
INNER CHANNELS FROM KUPREANOF ISLAND TO ETOLIN ISLAND-
INCLUDING THE CITIES OF...PETERSBURG...WRANGELL...KAKE
1057 AM AKST WED FEB 19 2014

...WINTER STORM WARNING WILL EXPIRE AT 11 AM AKST THIS MORNING...

THE HEAVIER SHOWERS ACROSS THE EASTERN KUPREANOF ISLAND AND THE
MAINLAND HAVE TAPERED OFF LEAVING A TOTAL SNOWFALL OF 7 INCHES
SINCE ABOUT MIDNIGHT. LIGHT SNOW SHOWERS ARE CONTINUING HOWEVER
ONLY AN INCH OR SO OF ADDITIONAL ACCUMULATION IS EXPECTED.

THIS WILL BE THE FINAL STATEMENT ON THE EVENT. 


$$

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
548 AM AKST WED FEB 19 2014

.SHORT TERM...EARLY MORNING SATELLITE LOOP REVEALS A WEAKENING
LOW ROTATING OVER THE SOUTHERN PANHANDLE WITH A WEAK TROUGH
EXTENDS SOUTHEAST TO BRITISH COLUMBIA COAST. A TROUGH ALSO
EXTENDS NORTHWEST AND MAKES A CONNECTION TO ANOTHER WEAKENING LOW
OVER PRINCE WILLIAM SOUND. PERSISTING OFFSHORE LOW LEVEL FLOW
OVER THE NORTHERN PANHANDLE MAINTAINS CLOUD FREE SKIES WITH GOOD
RADIATION COOLING. SEVERAL LOCATIONS REPORT PATCHY FOG. WINDS
REMAIN IN LIGHTER SIDE...EXCEPT NORTHERN LYNN CANAL WHERE SMALL
CRAFT LEVEL WINDS REMAIN THROUGH THE EARLY MORNING HOURS. ROUGH
SMALL CRAFT SEAS WILL PERSIST ACROSS THE OUTER WATERS.

 MODELS REMAIN IN GENERAL AGREEMENT WITH A WEAKENING LOW OVER THE
SOUTHERN PANHANDLE DISSIPATES BY EARLY THIS MORNING AND A
DEVELOPING LOW IN THE FAR SOUTHERN GULF TRACKS EASTWARD TO NEAR
HAIDA GWAII THROUGH TONIGHT. REFRESHED THE INHERITED FORECAST
PACKAGE WITH THE ECMWF FOR TODAY AND TONIGHT. RESULTANT CHANGES
ARE MINOR AS MODIFICATIONS ARE MOSTLY COSMETIC TOUCHES FOR FINE
TUNES.

 OFFSHORE LOW LEVEL FLOW WILL WEAKEN THIS AFTERNOON AND CONFINE
THE CLOUD FREE SKIES FARTHER NORTH TO THE NORTHERNMOST AREAS
THROUGH TONIGHT. THE LOW MOVING INTO THE SOUTHEASTERN GULF THIS
EVENING WILL CONTINUE TO DRIFT EAST TO NEAR HAIDA GWAII THROUGH
TONIGHT. CLOUDS WILL GRADUALLY INCREASE FROM THE SOUTHWEST TO
COVER MAJORITY OF THE PANHANDLE THROUGH TONIGHT. DUE TO
INCREASING CLOUDS...RADIATION COOLING WILL NOT BE AS STRONG AS
PREVIOUS NIGHT AND CHANCE OF PRECIPITATION SLOWLY INCREASE
THROUGH TONIGHT...ESPECIALLY OVER SOUTHERN HALF OF THE PANHANDLE.
EXPECT NO SIGNIFICANT WINDS ACROSS THE COASTAL WATERS...EXCEPT
CONTINUED SMALL CRAFT SEAS OVER THE OUTER WATERS.

.LONG TERM...THURSDAY ONSHORE FLOW ACROSS THE PANHANDLE WILL
OROGRAPHICALLY ENHANCE SHOWER ACTIVITY. GIVEN SOME WEAK
DEFORMATION BANDS VISIBLE IN THE VORTICITY FIELD PASSING
THROUGH FROM THE NORTHWEST, THE POP/QPF INDICATED BY THE MODELS
SEEM APPROPRIATE. DID RAISE THE POPS...ESPECIALLY ALONG THE
IMMEDIATE COAST LIKE SITKA FOR THESE SHOWERS. CONSIDERED GOING
ABOVE JUST A MERE INCH GIVEN RECENT HISTORY WITH SNOW SHOWERS, BUT
AFTER EXPERIMENTING WITH SOME HIGHER SNOW RATIOS, AN INCH AT THIS
POINT SEEMS SUFFICIENT. CANNOT RULE OUT THE SNOW SHOWERS WILL MIX
WITH RAIN IN THE SOUTHERN ZONES THURSDAY AFTERNOON. A WEAK ZONE OF
LOW PRESSURE WILL LIGHTEN WINDS OVER MUCH OF THE AREA THURSDAY
INTO THURSDAY NIGHT...WITH LIGHT NORTHERLIES OVER LYNN CANAL, AND
GENERALLY LIGHT SOUTHERLIES SOUTH OF ICY STRAIT/JUNEAU THROUGH
THURSDAY NIGHT. DID CHOOSE TO GO WITH CHANCE WORDING FOR THURSDAY
NIGHT AS OPPOSED TO THE MORE CATEGORICAL IMPLICATION OF SCATTERED
OR ISOLATED SHOWERS. CHANGED NATURE OF PRECIP BACK TO STRATIFORM
FOR FRIDAY IN RESPONSE TO FRONT DESCRIBED BELOW...HOWEVER STABILITY
OVER THE NORTHERN PANHANDLE MAY STILL BE UNSTABLE AT THAT POINT.

A WARM FRONT...PREVIOUSLY ADVERTISED BY THE MODELS WILL SLOW ITS
PROGRESSION NORTHEASTWARD FROM THE LAST PACKAGE. THIS FRONT WILL
CAUSE WINDS OVER THE PANHANDLE TO BEGIN A TRANSITION TO
EASTERLY/NORTHERLY LATE THURSDAY NIGHT INTO FRIDAY. MANY OF THE
MARINE ZONES HAVE STARK TRANSITIONS BETWEEN THURSDAY NIGHT INTO
FRIDAY, BUT DECIDED TO EASE IT BY IMPLYING THE STRONGER WINDS
FRIDAY WILL OCCUR LATE...MEANING FRIDAY NIGHT.

IN SLOWING DOWN THE FRONT THE RAIN/SNOW OVER THE SOUTHERN
PANHANDLE LATE THURSDAY NIGHT INTO FRIDAY HAS BEEN PUSHED BACK BY
6 HOURS OR SO AND SCALED BACK A POP CATEGORY.

AS LARGESCALE RIDGE BUILDS NORTHWEST OVER THE ALASKA
MAINLAND...NORTHERLY FLOW OVER NORTHWEST CANADA WILL DEEPEN COLD
AIR AND THUS CAUSE HIGH PRESSURE OVER THE YUKON TO STRENGTHEN.
WITH THE STALLED WARM FRONT STILL LURKING OFFSHORE, THE CROSS
BARRIER GRADIENT WILL INCREASE...INCITING OUTFLOW BREEZY
CONDITIONS. GIVEN THE SETUP OF OFFSHORE FLOW, PRECIPITATION
CHANCES WILL BE MINIMAL OVER THE EXTENDED PERIOD. ALTHOUGH SKIES
REPRESENTED AS CLOUDY AT THIS POINT...EXPECT THAT IN SUCCESSIVE
PACKAGES...CLOUDS WILL PART AS CONFIDENCE IN PATTERN GROWS.

LEFT TEMPERATURES ALONE IN THE LONG-RANGE. WARM UP AT THIS POINT
SCHEDULED FOR NEXT WEEK AS MID LEVELS TURN SOUTHEASTERLY.

ECWMF USED AS GUIDE FOR THURSDAY THROUGH FRIDAY. WPC AFTER THAT.
CONFIDENCE IN FORECAST AVERAGE FOR PERIOD.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-041.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ042-043-051.

&&

AHN/JWA