Small Craft Advisory 60, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
502 AM AKST TUE JAN 20 2015

.ANALYSIS AND UPPER LEVELS...
TWO FEATURES DOMINATE THE WEATHER MAP THIS MORNING. THIS FIRST IS
A DEVELOPING LOW MOVING NORTHWARD THROUGH THE SOUTHERN
GULF...THAT IS BEGINNING TO SPREAD RAIN SHOWERS AND GALE FORCE
WINDS INTO THE NORTHERN GULF. THE UPPER LEVEL TROUGH ASSOCIATED
WITH THIS LOW IS SPREADING RAIN AND SNOW SHOWERS FROM SOUTHERN
COOK INLET INTO THE INTERIOR SOUTHWEST MAINLAND. THIS SYSTEM WILL
CONTINUE TRACKING TO THE NORTH GULF COAST TODAY WHERE IT DISSIPATE
JUST EAST OF CORDOVA TONIGHT. THE OTHER FEATURE IS A BROAD LOW
COMPLEX CENTERED TO THE SOUTH OF THE CENTRAL ALEUTIANS. THIS
SYSTEM WILL REMAIN NEARLY STATIONARY FOR THE NEXT FEW DAYS BEFORE
SLIDING TOWARDS THE GULF AND DEVELOPING ON THURSDAY. BETWEEN THESE
TWO FEATURES LIES AN AREA OF RIDGING THAT STRETCHES FROM THE
CENTRAL BERING ONTO THE AKPENN...AND IS BEGINNING TO NOSE INTO THE
SOUTHWEST MAINLAND. AREAS OF LOW STRATUS HAVE DEVELOPED ALONG THE
SOUTHWEST COAST UNDER THIS RIDGE...WHICH WILL CONTINUE THROUGH
THIS MORNING AS THE RIDGING SLOWLY MOVES TO THE NORTH.

&&

.MODEL DISCUSSION...
THE MODELS HAVE ALL INITIALIZED WELL WITH THE DEVELOPING SYSTEM
OVER THE SOUTHERN GULF...AND REMAIN GOOD AGREEMENT WITH ITS LOW
TRACK INTO THE NORTH GULF THIS EVENING. THE NAM WAS PRIMARILY USED
FOR THIS LOW THROUGH WEDNESDAY MORNING TO BETTER CAPTURE THE FINE
DETAILS IN THE WINDS AS THE LOW TRACKS TO THE NORTH. THERE ARE
SOME SMALL DIFFERENCES IN THE MODELS AS TO HOW FAR WEST THE PRECIP
FROM THIS LOW WILL MOVE...WITH THE GLOBAL MODELS BRINGING STEADY
RAIN AND SNOW AS FAR WEST AS THE CENTRAL COPPER RIVER BASIN AND
VALDEZ AREA...WHILE THE HIGHER RESOLUTION NAM AND GEM REGIONAL
KEEP ALL OF THE PRECIP EAST OF CORDOVA. THE MORNING PACKAGE WILL
BRING SOME PRECIP FROM THE GULKANA AREA INTO THOMPSON PASS WITH
WITH SOME UPSLOPE FROM NORTHERLY FLOW ALOFT...BUT KEEP AND
RAINFALL OUT OF THE VALDEZ AREA AS DRYING WINDS FROM THE PASS
SHOULD PREVENT ANY PRECIP FROM REACHING THE GROUND. OUT
WEST...THERE IS GOOD AGREEMENT WITH THE GENERAL TRACK OF THE
COMPLEX LOW SOUTH OF THE ALEUTIANS WITH SOME MINOR DIFFERENCES
WITH INDIVIDUAL WAVES...ESPECIALLY IN THE NAM WHICH IS MORE
AGGRESSIVE WITH A WAVE DEVELOPING NEAR DUTCH HARBOR ON WEDNESDAY
AFTERNOON...WHICH WAS TREATED AS AN OUTLIER IN FAVOR OF THE MORE
CONSISTENT EC.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
PRESSURE GRADIENTS WILL INCREASE ACROSS MUCH OF SOUTHCENTRAL
TROUGH TODAY AS A WEAKENING LOW PRESSURE CENTER MOVES INTO THE
NORTH GULF. OUTFLOW WINDS WILL QUICKLY RAMP UP TODAY WITH THE
STRONGEST WINDS ACROSS THE NORTH GULF AND EASTERN KENAI. GAP FLOWS
MAY DIMINISH SOME TONIGHT AS THE LOW CENTER IN THE GULF
WEAKENS...BUT WILL INCREASE AGAIN SOME WITH THE NEXT LOW CENTER
APPROACHING WED. THE FRONT ASSOCIATED WITH THE LOW CURRENTLY OVER
THE EASTERN GULF WILL SPREAD SNOW INTO THE SOUTHERN AND EASTERN
COPPER RIVER BASIN TODAY. SNOW SHOULD DIMINISH THROUGH THIS
EVENING. WITH THE EXCEPTION OF PATCHY FOG...GENERALLY FAIR SKIES
WILL PREVAIL OVER MUCH OF SOUTHCENTRAL TONIGHT. INCREASING CLOUDS
WITH INCREASED CHANCES OF RAIN AND SNOW WILL MOVE TO THE NORTH TO
KODIAK...NORTH GULF WED NIGHT WITH THE APPROACH OF THE NEXT FRONT.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
REMNANTS OF A WEAK LOW NEAR KODIAK ISLAND WILL KEEP SNOW SHOWER
THREATS ACROSS THE EASTERN PORTIONS OF BRISTOL BAY AND THE LOWER
KUSKOKWIM VALLEY THROUGH THIS AFTERNOON. INCREASING NORTHEASTERLY
OFFSHORE FLOW WILL DEVELOP OVER THE AREA WEDNESDAY MORNING...KEEPING
COLD AND DRY CONDITIONS OVER THE REGION THROUGH THURSDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A MODERATE GALE FORCE FRONT WILL DEVELOP ACROSS THE ALEUTIANS
THROUGH THURSDAY...WITH INCREASING NORTHEAST WINDS ACROSS THE
ENTIRE BERING SEA AND ALEUTIAN CHAIN. RAIN AND SNOW WILL GENERALLY
REMAIN OVER THE ALEUTIAN CHAIN...WITH DRIER CONDITIONS ACROSS THE
CENTRAL AND EASTERN BERING THROUGH THURSDAY.

&&

.LONG TERM FORECAST (THURSDAY THROUGH MONDAY)...WITH MODELS
STARTING TO COME INTO BETTER AGREEMENT FOR THURSDAY...WE WERE ABLE
TO MAKE SOME ADJUSTMENTS AND REFINEMENTS TO THE FORECAST.
HOWEVER...THERE ARE STILL LARGE ENOUGH DIFFERENCES DURING THE
FRIDAY THROUGH MONDAY PERIOD THAT MINIMAL CHANGES WERE MADE TO THE
FORECAST. THE LARGE LOW SOUTH OF THE ALEUTIANS LOOKS LIKE IT WILL
GRADUALLY MOVE TOWARD THE GULF...WHICH WOULD BRING A MORE ACTIVE
WEATHER PATTERN TO SOUTHCENTRAL AK FOR THE WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DEK
SOUTHCENTRAL ALASKA...BC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TP
LONG TERM...MBS