Heavy Snow in Alaska, February 1, 2008

SOUTHEAST ALASKA FORECAST DISCUSSION
1230 PM AST FRI FEB 1 2008

.SYNOPSIS...
.SHORT RANGE...DEFORMATION BAND / TROUGH PUSHING THROUGH
SOUTHEAST ALASKA FRIDAY HAS DROPPED SEVERAL INCHES OF SNOW
ACROSS THE CENTRAL PANHANDLE AREA.  A HIGH RATIO OF 30:1 TO
80:1 SNOW HAS DROPPED SEVERAL INCHES OF FLUFF ACROSS THE AREA
WITH GENERALLY LESS THAN A TENTH OF AN INCH OF WATER.  THE
STRONG WEST FLOW OF THE GULF KEEPS THE SNOW SHOWERS FORMING OF
THE CENTRAL GULF AND THEN STREAMING INTO THE COASTAL AREA FROM
ABOUT SITKA SOUTHWARD. THE HEAVIEST SHOWERS SEEM TO IMPACTING
SITKA THROUGH THE EARLY MORNING.

WE WILL SEE THE LOW OVER THE SOUTH CENTRAL GULF THIS AFTERNOON
SLIDE SOUTHEASTWARD TO THE PACIFIC NORTHWEST VERY SIMILARLY TO
THE REST HAVE DONE LATELY.  AN UPPER LEVEL TROUGH ABOUT A LOW
OVER NORTHERN ALASKA WILL ROTATE ACROSS THE KUSKOKWIM REGION
AND WILL HELP TO SPIN UP ANOTHER LOW OVER THE NORTHERN HALF OF
THE GULF. THIS WILL MOVE EAST TO CENTRAL GULF SATURDAY AFTERNOON.

EXPECT TO SEE A COUPLE INCHES OF SNOW YET ACROSS THE PANHANDLE
REGION TODAY FROM SHOWERS PERSISTING AND THE LIGHT OVERRUNNING
THAT WILL CONTINUE...BUT SHOULD SEE A MORE STEADY
PRECIPITATION START TO MOVE INTO THE AREA LATER SATURDAY WHEN LOW
GETS CLOSER.

MEANWHILE THE COLD AIR ENTRENCHED OVER THE NORTHERN AND INNER
CHANNELS WILL CONTINUE TO PERSISTS THROUGH SATURDAY. LOCALLY
VERY WINDY CONDITIONS IN THE SKAGWAY AREA PERSIST WITH GUSTS
NEAR 40 MPH AND THE WIND CHILLS AT 25 TO 35 BELOW.  THE WINTER
WEATHER ADVISORY HAS BEEN EXTENDED YET AGAIN... AND IF THE
WINDS DO NOT ABATE BY THIS AFTERNOON I EXPECT TO SEE THEM
CONTINUE OVERNIGHT SO WILL EXTEND THE ADVISORY TO SATURDAY.

.LONG RANGE...GENERALLY SPEAKING...LONG RANGE SHAPING UP TO BE
SNOWY THROUGH ABOUT TUE WITH SLOWLY MODERATING TEMPS. THEN COLD
HIGH PRESSUE RETURNS TO THE YUKON MID WEEK FOR DRIER COLDER
WEATHER N AND STORMINESS SHIFTING FARTHER S.

POTENTIAL FOR SIGNIFICANT SNOWFALL EVENT ACROSS THE CENTRAL
PANHANDLE FROM LATE SATURDAY NIGHT THROUGH SUNDAY. CYCLOGENESIS
SAT NIGHT RESULTS FROM UPPER LEVEL TROUGH MOVING SE FROM INTERIOR
AK TOWARD PANHANDLE MERGING WITH MOIST CYCLONE CURRENTLY NEAR AK
PENN. 12Z MODELS VARY ON DEVELOPMENT AND TRACK OF SFC LOW
APPROACHING PANHANDLE FOR THIS EVENT. CONCERN HERE IS THAT MODELS
MAY BE TRYING TO RESOLVE SEPERATE LOWS...MAIN SYNOPTIC CENTER
CUTTING TOWARD CENTRAL AND SOUTHERN PANHADLE SUN AND LOW TO
DEVELOP WEST OF YAKUTAT ON LEE /SE/ SIDE OF CHUGACH RANGE. MODELS
CONSISTENT DEPICTING MOIST AIR MASS AND SIGNIFICANT LIFT
OVERNIGHT SAT INTO SUN...ESPECIALLY N HALF OF PANHANDLE...
ASSOCIATED WITH STRONG MID LEVEL DEFORMATION BANDING. ONE HALF
INCH OR MORE OF LIQUID PRECIP IS FCST FOR SUN WHICH COULD EASILY
ADD UP TO A FOOT OF SNOW. WILL ISSUE HEAVY SNOW WATCH FOR AREA
NORTH OF SUMNER STRAIT FOR LATE SAT INTO SUN. AS USUAL...THE
EXACT TRACK OF THE LOW...OR LOWS...WILL DICTATE WHERE THE
HEAVIEST SNOW BANDS WILL FORM. SW GALES ON S AND W SIDES OF LOW
CENTER SUN ADD TO POTENTIAL HAZARD OF THIS STORM.

ANOTHER POTENTIAL SIGNIFICANT LOW PRESSURE SYSTEM WILL APPROACH
THE SOUTHERN PANHANDLE MONDAY INTO TUESDAY MORNING. THIS SYSTEM
IS CURRENTLY THE MASSIVE WAVE IN SATELLITE IMAGRY ON THE TROPICAL
MOISTURE PLUME JUST WEST OF DATELINE AT 40N. MODEL SOLUTION
SPREAD IS STILL QUITE LARGE ON THIS SYSTEM BUT THINKING HEAVIER
SNOW AMOUNTS WITH THIS SYSTEM WILL BE A BIT FARTHER SOUTH THAN
THE IMPACT AREA ON SUN. WILL KEEP FOCUS ON SUN SYSTEM FOR NOW.

CONTINUED BLO AVE TEMPS THROUGH THE EXTENDED RANGE. THROUGH ABOUT
TUE THERE IS MORE OVER WATER TRAJECTORY OF INCOMING AIR MASSES SO
TEMPS WILL MODERATE SOME AND SUB ZERO TEMPS WILL BE NON EXISTENT.
HOWEVER...PRESSURE GRADIENTS AND FLOW ALOFT BECOME NORTHERLY
AGAIN MID WEEK FOR A REINFORCED SHOT OF COLD INTERIOR AIR. TA

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HEAVY SNOW AKZ023
      ...SNOW ADVISORY AKZ021-024>026
      ...WINTER WEATHER ADVISORY AKZ018
      ...HEVY SNOW WATCH SUN NIGHT-MON AKZ017-026
MARINE...SMALL CRAFT ADVISORY PKZ021-022-041>043-051

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JUNEAU AK
941 AM AST FRI FEB 1 2008

AKZ020>026-020100-
GLACIER BAY-EASTERN CHICHAGOF ISLAND-
SALISBURY SOUND TO CAPE FAIRWEATHER COASTAL AREA-
CAPE DECISION TO SALISBURY SOUND COASTAL AREA-
EASTERN BARANOF ISLAND AND SOUTHERN ADMIRALTY ISLAND-
JUNEAU BOROUGH AND NORTHERN ADMIRALTY ISLAND-
INNER CHANNELS FROM KUPREANOF ISLAND TO ETOLIN ISLAND-
INCLUDING THE CITIES OF...GUSTAVUS...HOONAH...ELFIN COVE...
PELICAN...SITKA...PORT ALEXANDER...ANGOON...JUNEAU...PETERSBURG...
WRANGELL...KAKE
941 AM AST FRI FEB 1 2008

...VERY LOW WATER CONTENT IN SNOW TODAY...

SNOW IS FALLING INTO THE VERY COLD AIR OVER THE PANHANDLE TODAY.
THESE COLD TEMPERATURES ARE CREATING MUCH DRIER SNOW THAN THE AREA
IS USED TO AND IS MORE TYPICAL OF INTERIOR ALASKA WEATHER. USUALLY
SNOW TO LIQUID RATIOS ARE 10 TO 1 OR 20 TO 1 OVER SOUTHEAST
ALASKA...BUT TODAY SNOW RATIOS ARE AS HIGH AS 80 TO 1. THE JUNEAU
FORECAST OFFICE RECORDED 4 INCHES OF SNOW FROM 3 AM TO 9 AM THIS
MORNING...BUT ONLY FIVE HUNDREDTHS OF MELTED EQUIVALENT. FAST
MOVING VEHICLES ARE EASILY BLOWING THE SNOW AND CREATING LOW
VISIBILITY ON AREA ROADS.

ANOTHER WINTER STORM MAY BRING HEAVIER SNOW SATURDAY NIGHT INTO
SUNDAY.

NF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
111 PM AST FRI FEB 01 2008

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0109 PM     HEAVY SNOW       SITKA                   57.21N 135.45W
02/01/2008  M9.0 INCH                           AK   TRAINED SPOTTER

            TWO INCHES SINCE 830 AM. STORM TOTAL OF 9 INCHES
            OVERNIGHT THROUGH 1 PM.

&&

NWF