Winter Storm Watch 9, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
149 PM AKST THU DEC 13 2012

.DISCUSSION...

MODELS...SHORT RANGE SHOWS GOOD AGREEMENT MOVING SYSTEM OUT OF
THE INTERIOR THIS EVENING. MID RANGE DIFFERENCES SHOW UP IN THE
HANDLING OF THE SYSTEM THAT DEVELOPS IN THE NORTHWEST PACIFIC
NEXT WEEK. MODELS ARE IN PRETTY GOOD AGREEMENT IN HANDLING A
LOW PRESSURE SYSTEM MOVING INTO THE GULF EARLY NEXT WEEK.

ALOFT...AT 500 HPA...ZONAL FLOW ACROSS THE INTERIOR BREAKS DOWN
AS A TROUGH DIGS IN OVER THE EASTERN HALF OF THE INTERIOR BY
SATURDAY MORNING WITH ANOTHER TROUGH OVER THE BERING STRAIT AND
NORTHWEST COAST. A WEAK RIDGE TRANSITS THROUGH THE FLOW SOUTH OF
THE ALASKA RANGE MONDAY AND TUESDAY KICKING THE TROUGH EAST.
A LONG WAVE TROUGH WILL MOVE OVER THE WEST COAST BEHIND THE
RIDGE AND REMAIN OVER THE STATE THROUGH NEXT WEEK.
AT 850 HPA...GOOD PUSH OF COLD AIR BEHIND THE CURRENT SYSTEM
INITIALIZE AT 7C BELOW EXPECT 18C BELOW BY FRIDAY MORNING AND
26C BELOW BY SATURDAY MORNING.

SURFACE...MAIN LOW PROGRESSING EAST DRAGGING FRONT WITH IT SNOW
SHUTTING OFF FROM WEST TO EAST THROUGH THE EVENING. GOOD CLEARING
TROUGH NEARING TANANA WILL PROGRESS SLOWLY EAST AND SOUTH THROUGH
FRIDAY EVENTUALLY MOVING THROUGH FAIRBANKS DURING THE DAY FRIDAY
AND TO THE BORDER OVERNIGHT. GOOD COLD AIR ADVECTION BEHIND THE
FRONT MAY KICK UP THE WINDS IN A FEW PLACES BUT NO SIGNIFICANT
WINDS EXPECTED. TEMPERATURES IN THE NORTHWEST INTERIOR COOLING
RAPIDLY BEHIND THE TROUGH TONIGHT WITH THE FULL EFFECT OF THE COLD
REACHING THE REMAINDER OF THE INTERIOR BEGINNING FRIDAY AFTERNOON.
LOOK FOR TEMPERATURES TO FALL FRIDAY NIGHT THROUGH SUNDAY MORNING
WITH LOWS IN THE 25 TO 45 BELOW RANGE FOR MOST INTERIOR LOCATIONS.
LOW IN THE GULF OF ALASKA WILL SWING A TROUGH AROUND OVER THE
SOUTHEAST INTERIOR WITH GOOD MOISTURE FRIDAY NIGHT THROUGH
SATURDAY THAT WILL PRODUCE SIGNIFICANT SNOW IN SOUTHERN ZONE 224
AND EASTERN ZONE 226. UPSLOPE AREAS COULD SEE OVER A FOOT OF NEW
SNOW SO ISSUING A WATCH FOR THE AREA SOUTH OF CHICKEN AND EAST OF
THE RICHARDSON HIGHWAY. SNOW WILL ALSO FALL AS FAR NORTH AS EAGLE
BUT NOT IN SIGNIFICANT AMOUNTS.

ARCTIC COAST...SNOW ENDING IN THE EASTERN ARCTIC COAST THIS
EVENING...THEN PREDOMINANTLY CLEAR TO PARTLY CLOUDY THROUGH EARLY
SUNDAY WITH THE EXCEPTION OF PATCHES OF STRATUS IN THE COASTAL
AREAS THAT MAY SHED A FEW FLURRIES. SUNDAY A FRONT WILL BRING SOME
SNOW TO THE NORTHWEST COAST BUT NOT IN SIGNIFICANT AMOUNTS.

WEST COAST...CLEARING CONTINUES THROUGH THE INTERIOR ZONES. COLD
AIR ADVECTION WILL PROGRESS SOUTH AND EAST THROUGH FRIDAY. EXPECT
TEMPERATURES TO CONTINUE TO FALL TONIGHT THEN REMAIN FAIRLY STEADY
FRIDAY THEN SLOWLY RISING SATURDAY. SOME LOCALLY GUSTY WINDS
TONIGHT AS THE COLD AIR MOVES IN BUT GENERALLY LIGHT WINDS.
DISSIPATING FRONTAL SYSTEM REACHES THE COAST SATURDAY REMAINING INTO
SUNDAY AND MAY BRING SOME SNOW SHOWERS TO MAINLY THE COAST.

INTERIOR...CLOUDS WILL CLEAR OUT ON FRIDAY BUT UNTIL THEN
OCCASIONAL FLURRIES ACROSS MOST OF THE AREA FROM NENANA EAST. GOOD
COLD AIR ADVECTION WILL PUSH WEEKEND TEMPERATURES DOWN RAPIDLY
FRIDAY NIGHT. BIG ISSUE WILL BE THE SNOW IN THE SOUTHEAST INTERIOR
SATURDAY...EAST OF DELTA JUNCTION.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR AKZ225-AKZ226.
&&

SDB DEC 12