Storm Warning 7, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
257 PM AKST TUE JAN 19 2016

.SHORT TERM...SATELLITE IMAGERY SHOWS 990 MB LOW TRACKING FROM THE
NORTHERN COASTAL WATERS WESTWARD INTO THE NORTHWEST GULF WHILE
WEAKENING. ANOTHER LOW WILL BEGIN TO MOVE UP FROM THE SOUTH INTO
THE AK GULF WEDNESDAY. AN AREA OF HIGH PRESSURE WILL REMAIN OVER
WESTERN CANADA.

PRECIPITATION BANDS ROTATING AROUND THE LOW TOOK ON A MORE
SHOWERY NATURE THROUGH THE DAY WITH A FEW BREAKS IN CLOUD COVER
BETWEEN THE BANDS. CURRENTLY SHOWER BAND OVER THE NORTHERN
PANHANDLE IS SHEARING APART WHILE ANOTHER BAND IS MOVING OVER THE
SOUTHERN PANHANDLE TOWARDS THE CENTRAL REGIONS UNDER TROUGH
EXTENDING FROM MAIN LOW WITH AN ELONGATED BAND ALONG THE
PANHANDLE COAST. AS THE LOW CENTER MOVES WEST SHOWER ACTIVITY WILL
DIMINISH OVERNIGHT WITH ONLY SOME SCATTERED SHOWERS FOR
WEDNESDAY. SOUTHERLY FLOW HAS KEPT MOST OF THE PANHANDLE IN THE
UPPER 30S TO LOW 40S. WITH THE EXCEPTION OF THE FAR NORTHERN
PANHANDLE AND WIND SHELTERED AREAS OVER THE CENTRAL PANHANDLE MOST
LOCATIONS RECEIVED ONLY RAIN. THOSE SPOTS THAT DID GET SNOW OR A
RAIN SNOW MIX ONLY ACCUMULATED AROUND AN INCH OR ONLY A TRACE.
FOR TONIGHT EXPECT SIMILAR QPF AMOUNTS AND TEMPERATURE PROFILE SO
ONCE AGAIN FAR NORTHERN PANHANDLE BELOW FREEZING WITH ONLY AN INCH
OF SNOW ACCUMULATION, WIND SHELTER CENTRAL PANHANDLE LOCATIONS
JUST NEAR FREEZING WITH SOME MIX OF SNOW POSSIBLE BUT NO
ACCUMULATION AND ELSEWHERE TEMPS IN THE MID 30S WITH ANY PRECIP
FALLING AS RAIN SHOWERS. WITH SMALL DEW POINT DEPRESSION, LIGHTER
WINDS AND STILL SOME POTENTIAL BREAKS IN CLOUD COVER ONCE AGAIN
HAVE POTENTIAL FOR FOG FORMATION THIS EVENING OVER THE CENTRAL
PANHANDLE. WITH INSTABILITY OVER THE COASTAL WATERS THIS EVENING
ALONG WITH SOME LIGHTNING STRIKES EARLIER KEPT IN SLIGHT CHANCE OF
T-STORMS.

WINDS DROPPED THROUGH THE DAY AS PRESSURE GRADIENT BETWEEN THE
GULF LOW AND HIGH PRESSURE OVER WESTERN CANADA WEAKENED. GALES
ON THE NORTH SIDE OF THE LOW IN THE NORTHERN GULF WILL DROP THIS
EVENING. INNER CHANNEL WINDS WILL ALSO DIMINISH THROUGH THE
EVENING AS THE CURRENT LOW DEPARTS. AS THE WEDNESDAY LOW ADVANCES
INTO THE SOUTHERN GULF NORTHERLY PRESSURE GRADIENT WILL TIGHTEN
WITH INCREASING WINDS OVER THE INNER CHANNELS ALONG WITH OUTFLOW
WINDS. THE SOUTHERN AK GULF WILL PICK UP TO MAX SMALL CRAFT BY
WEDNESDAY AFTERNOON.

MODELS IN GOOD AGREEMENT AGAIN AND VARIED LITTLE FROM PREVIOUS
FORECAST. USED SOME HI RES NAM FOR OUTSIDE WATER WINDS AND DNG5
FOR POP BUT OVERALL CHANGES WERE MINOR. FORECAST CONFIDENCE IS
JUST ABOVE AVERAGE.

.LONG TERM...MAIN ISSUE IN THE EXTENDED RANGE FORECAST OCCURS
EARLY ON WITH ANOTHER STRONG GALE FORCE FRONT TRACKING NORTH OVER
THE EASTERN GULF WEDNESDAY NIGHT. THE LOW ITSELF IS CURRENTLY
FORECAST TO REMAIN OVER THE CENTRAL GULF, SO STRONG WIND HEADLINES
FOR THE SOUTHERN OUTER COAST VICE A HIGH WIND WATCH SEEMS SUFFICIENT
AT THIS TIME. A TIGHTENING GRADIENT WITH THE FRONT PRESSING UP
AGAINST RELATIVELY WEAK HIGH PRESSURE OVER WESTERN CANADA IS
MAKING STRONG WINDS IN SKAGWAY AND DOWNTOWN JUNEAU WEDNESDAY NIGHT
LIKELY AS WELL. FOR THE JUNEAU AND DOUGLAS AREA, CROSS BARRIER
FLOW, CRITICAL LEVEL, AND INVERSION POTENTIAL ARE ALL FAVORABLE
FOR A MOUNTAIN WAVE EVENT, BUT DO NOT WANT TO CHARACTERIZE THIS AS
A TAKU WIND EVENT, SINCE WINDS WILL BE NOWHERE STRONG ENOUGH TO
QUALIFY FOR SUCH A MONIKER. STILL, IT WILL BE WINDY AND THERE WILL
BE IMPACTS. ELSEWHERE, POTENTIAL FOR STRONG WINDS EXISTS IN
VARIOUS OTHER PLACES AND HAVE HEDGED IN THAT DIRECTION WITH WIND
SPEEDS BUT KEPT GUSTS LIMITED TO 35 MPH.

DEEP LAYER SOUTHERLY FLOW WILL CONTINUE TO ADVECT IN WARM LOW
LEVEL AIR, SO THERE IS NO SIGNIFICANT SNOWFALL IN THE EXTENDED
RANGE FORECAST EXCEPT FOR THE FAR NORTHERN ZONES AND HYDER, WHERE
3 TO 5 INCHES IS POSSIBLE BETWEEN THURSDAY MORNING AND FRIDAY
MORNING. POSSIBILITY OF SNOW IN THE MENDENHALL VALLEY WEDNESDAY
NIGHT AS WELL.

BEYOND THE FRONT CAUSING THE WINDS AND PRECIP WEDNESDAY NIGHT, THE
EXTENDED RAGE FORECAST CONTINUES TO BE RATHER WET WITH FRONTS AND
WAVES AFFECTING SOUTHEAST ALASKA DAILY INTO THE MIDDLE OF NEXT
WEEK.

USED A BLEND OF NAM AND GEM FOR UPDATES TO PRESSURE AND WIND
WEDNESDAY NIGHT INTO THURSDAY. POP FOR WEDNESDAY NIGHT FROM A
BLEND OF GFS22 AND GEM. QPF A TRUNCATED BLEND OF GFS22 AND GEM.
REMAINDER OF THE MID RANGE UNCHANGED FROM LAST NIGHT. POP FROM
SATURDAY ONWARD UPDATED WITH THE LATEST WPC. OVERALL FORECAST
CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ041>043-051.
         SMALL CRAFT ADVISORY FOR PKZ022-033>036-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

PRB/FRITSCH

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