Blizzard and High Wind in Alaska, January 17, 2014

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKST THU JAN 16 2014

.ANALYSIS AND UPPER LEVELS...
THE WAVE WHICH BROUGHT A BRIEF PERIOD OF MODERATE TO HEAVY SNOW
ACROSS SOUTHCENTRAL IS MOVING RAPIDLY NORTH ACROSS THE COPPER RIVER
BASIN THIS AFTERNOON. SUBSIDENCE AND LINGERING LOW LEVEL MOISTURE ON
THE BACKSIDE OF THIS PRODUCED AREAS OF FOG ACROSS SOUTHCENTRAL. A
DEVELOPING STORM SYSTEM OVER THE NORTH PACIFIC IS FULLY OCCLUDED AND
HAS A CENTRAL PRESSURE IN THE LOW TO MID 950S. THE LOW WILL BECOME
STACKED WITH THE UPPER CENTER AND MOVE TO OVER THE AK PEN FRI
AFTERNOON WITH A PRESSURE IN THE 950S. A SECONDARY AS EQUALLY STRONG
LOW WILL DEVELOP ALONG THE FRONTAL TROUGH AS IT BOWS NORTH INTO THE
EASTERN BERING SEA FRI. THE ASSOCIATED FRONT SWEEPS NORTH AND EAST
AND EXTENDS ACROSS INTERIOR SW ALASKA...THROUGH SOUTHCENTRAL...TO
ALONG THE NORTHERN AND EASTERN GULF FRI AFTERNOON. THE FRONT
CONTINUES NORTH AND EAST AND WEAKENS SAT.

.MODEL DISCUSSION...
MODELS OVERALL INITIALIZED FAIRLY WELL WITH THE SYNOPTIC PATTERN.
SOME DIFFERENCES IN INITIALIZING THE DEVELOPING LOW OVER THE NORTH
PACIFIC WERE FAIRLY MINOR. A SHIP OB NEAR THE LOW CENTER INDICATED
THAT THE ECMWF 18Z FORECAST POSITION WAS BEST...BUT THAT THE PRESSURE
WAS OFF BY A COUPLE OF MILLIBARS. FORECAST TRENDS ARE SIMILAR THROUGH
SAT MORNING...THEN THE NAM BECOMES THE OUTLIER.

.SHORT TERM FORECAST...
.SOUTHCENTRAL ALASKA...
WARM...WINDY...AND WET CONDITIONS SPREAD ACROSS THE REGION FRI AS THE
NORTH PACIFIC LOW MOVES TOWARD THE AK PEN AND THE FRONT PUSHES NORTH
INTO THE GULF OF ALASKA. STRONG PRESSURE GRADIENTS AND UPPER JET
SUPPORT BRING STRONG GAP AND CHINOOK CONDITIONS BEGINNING FRI MORNING
AND CONTINUING INTO FRI NIGHT. ADDITIONALLY...WARM AND MOIST AIR WILL
SPREAD ACROSS THE AREA FRI AND PRODUCE VARIED PRECIPITATION TYPES.
UPSLOPE FLOW WILL PRODUCED MODERATE TO HEAVY RAINS ALONG THE NORTH
GULF COAST AND EASTERN KENAI PENINSULA FRI WITH QPF VALUES IN THE 3
TO 5 INCH RANGE. PRECIPITATION WILL BECOME MORE SHOWERY AND CHANGE
MORE TOWARD SNOW ON SAT AS COLD AIR SWEEPS IN FROM THE WEST.

.SW ALASKA...
THE DEVELOPING LOW AND ASSOCIATED FRONTAL TROUGH APPROACHING THE AK
PEN WILL BRING WARMING TEMPS AND WET AND WINDY CONDITIONS TO SW
ALASKA. COLD DRAINAGE FLOW INITIALLY WILL KEEPS TEMPS BELOW FREEZING
AS MOISTURE REACHES THE DELTA LATE TONIGHT. THE ACCOMPANIED STRONG
WINDS WILL BRING IN BLIZZARD POTENTIAL. MIXED PRECIPITATION TYPES
WILL BECOME MORE PROBLEMATIC FRI AS WARM AIR SPREADS IN FROM THE
SOUTH AND EAST. FREEZING RAIN POTENTIAL WILL BE RELATIVELY LIGHT OVER
THE LOWER KUSKOKWIM FRI AS DOWNSLOPE CONDITIONS SHOULD BE FAIRLY
WIDESPREAD. SNOW SHOWERS SPREAD ACROSS SW ALASKA SAT AS COLD AIR
SPREADS IN FROM THE WEST.

ALEUTIANS/BERING SEA...
THE STORM MOVING SNOW WILL BRING BLIZZARD POTENTIAL TO THE EASTERN
ALEUTIANS TONIGHT. BLIZZARD CONDITIONS OVER THE EASTERN ALEUTIANS MAY
BECOME QUESTIONABLE IF THE WARMER AIR SPREADS TOO FAR WEST TONIGHT.
BLIZZARD CONDITIONS END OVER THESE AREAS FRI NIGHT.

.LONG TERM FORECAST...
WITH THE LONGWAVE PATTERN STAYING IN PLACE INTO THE MIDDLE OF THE
NEXT WEEK A SEASONABLY WARM AND VERY ACTIVE WEATHER PATTERN WILL
CONTINUE FOR THE SOUTHERN MAINLAND OF ALASKA. A COLD AND SHOWERY
AIRMASS STAYS IN PLACE OVER THE BERING. BETWEEN THE TWO AIR
MASSES...THE POTENTIAL FOR MORE SIGNIFICANT WINTER WEATHER WILL
INCREASE EARLY NEXT WEEK OVER SOUTHWEST ALASKA AND THE EASTERN BERING
WHERE THE TWO AIR MASSES WILL CLASH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 155 185 195
         HIGH WIND WARNING 101 111
         FREEZING RAIN ADVISORY 152
MARINE...GALES 120 125 130 131 132 136 137 138 139 155 160 165 170
         171 173 174 176 179 180 181 185 411 412 413 414
         STORM WARNING 119 150 172 185
         HEAVY FREEZING SPRAY 179 180 185 411 412 413 414
FIRE WEATHER...NONE.

RMC JAN 14