Small Craft Advisory 67, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKST TUE JAN 21 2014

.ANALYSIS AND UPPER LEVELS...
A WEAK DISTURBANCE WITH RAIN AND SNOW OVER SOUTHCENTRAL AND FREEZING
RAIN TO THE ANCHORAGE BOWL THIS MORNING IS MOVING RAPIDLY NORTH. THE
MAIN TROUGH AXIS STRETCHES ACROSS SW ALASKA TO OVER THE GULF. RAIN
AND SNOW SHOWERS WERE EVIDENT ACROSS SW ALASKA WITH RAIN ALONG THE
GULF COAST. SNOW SHOWERS WERE EVIDENT ACROSS THE BERING SEA WITH COLD
ADVECTION ON THE BACKSIDE OF THE TROUGH MOVING NORTH ACROSS THE
SOUTHERN MAINLAND. THE NAM OVERALL INITIALIZED THE BEST ON FREEZING
LEVELS FROM THE SW INTERIOR/EASTERN BRISTOL BAY TO THE
GULF/SOUTHCENTRAL. THE GFS INITIALIZED FREEZING LEVELS AT PAMC AND
PANC WERE SIGNIFICANTLY LOWER THAN THE RADIOSONDE DATA INDICATED.

THE SHORT WAVE EXTENDING ACROSS SW ALASKA AND THE GULF MOVES NORTH
ACROSS THE INTERIOR TONIGHT. A SECONDARY WAVE AND FRONTAL SURFACE
REFLECTION MOVES TO THE NORTH GULF/BRISTOL BAY WED AFTERNOON THEN
OVER THE CENTRAL MAINLAND WED EVENING. A UPPER VORTEX AND SURFACE
REFLECTION OVER THE NORTH PACIFIC MOVES NORTH IN THE LONG WAVE TROUGH

TO NEAR THE EAST ALEUTIANS THU MORNING THEN TO THE EASTERN BERING SEA
THU EVENING. RELATIVELY DEEP SOUTHERLY FLOW SETS UP OVER THE EAST
PACIFIC TO OVER THE EASTERN MAINLAND THU.

.MODEL DISCUSSION...
THE GLOBAL MODELS ARE ALL IN RELATIVELY GOOD AGREEMENT AND REASONABLE
THROUGH THE SHORT TERM. THE NAM APPEARS TO BE THE OUTLIER ON THE MAIN
LOW CENTER WHICH HEADS TOWARD THE EAST ALEUTIANS/WESTERN AK PEN WED
NIGHT.

.SHORT TERM FORECAST...

.SOUTHCENTRAL ALASKA...
RAIN AND SNOW INLAND WITH RAIN ALONG THE COAST WILL DIMINISH SOME
LATE TONIGHT AS THE WAVE MOVES INTO THE INTERIOR. ALSO THERE WILL
LIKELY BE AREAS OF ISOLATED FREEZING RAIN IN THE SUSITNA VALLEY THIS
EVENING. RAIN WILL RE-INTENSIFY ALONG THE COAST THU AS A FRONTAL
TROUGH MOVES NORTH INTO THE GULF. THERE WILL LIKELY BE SOME SPILL
OVER INTO INLAND AREAS OVER THE MATSU/ANCHORAGE BOWL. FREEZING LEVELS
WILL CONTINUE TO RISE ACROSS SOUTHCENTRAL THROUGH THIS WEEK WITH
VALUES AROUND 5000 FT INLAND TO NEAR 8000 FT ALONG THE GULF COAST.
RAIN WILL LIKELY CONTINUE ALONG THE GULF WITH NORTH MOVING FRONTAL
TROUGHS AND INCREASE IN INTENSITY THU AND FRI WITH UPPER JET SUPPORT.
GAP FLOWS INLAND WILL DIMINISH TONIGHT BUT SHOULD INTENSIFY WED AND
THU WITH THE APPROACH OF THE FRONTAL TROUGH IN THE GULF AND AS THE
STACKED LOW CENTER MOVES TOWARD THE EAST ALEUTIANS/EAST BERING SEA
THU.

SOUTHWEST ALASKA/ALEUTIANS/BERING SEA...
SHOWERS ACROSS THE REGION WILL DIMINISH TONIGHT AND TRANSITION TO ALL
SNOW SHOWERS BEFORE ENDING AS COLD AIR SPREADS IN FROM THE SW. THERE
WILL LIKELY BE SOME PATCHY FOG ACROSS THE AREA TONIGHT AS LOW LEVEL
MOISTURE IS TRAPPED UNDER SUBSIDENCE INVERSIONS. MOISTURE AND WINDY
CONDITIONS SPREAD IN FROM THE SE WED. THE LEADING EDGE OF
PRECIPITATION SHOULD BE GENERALLY ALL SNOW THEN SLOWLY TRANSITION TO
A MIX AS IT SPREADS WEST. THIS WILL BRING A SHOT AT FREEZING RAIN
POTENTIAL TO THE REGION WED AND WED NIGHT.

BERING SEA/ALEUTIANS...
ACTIVE WEATHER CONDITIONS ARE EXPECTED OVER THE EAST ALEUTIANS AND
EASTERN BERING SEA OVER THE NEXT COUPLE OF DAYS. A FRONTAL TROUGH
MOVING AHEAD OF FRONTAL TROUGH WILL BRING RAIN AND SNOW TO THE
EASTERN ALEUTIANS WED AND SNOW AND BLOWING SNOW TO THE PRIBILOFS LATE
WED NIGHT AND THU. SNOW SHOWERS OVER THE WESTERN BERING SEA DIMINISH
AS HIGH PRESSURE BUILDS OVER THE REGION.

.LONG TERM FORECAST...
THERE ARE SOME HINTS AT THIS ACTIVE AND WARM PATTERN BREAKING DOWN
NEXT WEEK...BUT NOTHING WORTH LATCHING ONTO AT THIS POINT. WE WILL
KEEP AN EYE ON THIS POSSIBILITY IN THE COMING DAYS. UNTIL
THEN...EXPECT CONTINUED ABOVE NORMAL TEMPERATURES FOR MUCH OF THE
MAINLAND AND PERIODS OF PRECIPITATION ESPECIALLY ALONG THE COASTAL
AREAS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 119 120 131 132 138 150 155 160 165 170 172 173 174 179
FIRE WEATHER...NONE

RMC JAN 14