Small Craft Advisory 461, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT TUE JUN 4 2013

.ANALYSIS AND UPPER LEVELS...IN THE UPPER LEVELS THERE IS A LOW
CENTERED IN ALONG THE NORTH GULF COAST WITH A TROUGH THAT EXTENDS TO
THE SOUTHWEST TO A WEAK LOW CENTER NEAR THE CENTRAL ALEUTIANS.
THE UPPER LEVEL LOW ALONG THE NORTH GULF COAST...IN CONJUNCTION WITH
THE SURFACE LOW EAST OF KODIAK ISLAND...IS PROVIDING THE IMPETUS FOR
WIDESPREAD SHOWERS OVER SOUTH CENTRAL ALASKA AND WESTWARD INTO THE
BRISTOL BAY REGION.
THE 250 MB JET STREAM IS RIDING SOUTH OF THESE LOWS AND THE TROUGH
CONNECTING THEM. THIS JET STREAM IS ALSO FUELING THE LARGE SURFACE
LOW THAT IS WELL SOUTH OF THE ALEUTIANS THIS AFTERNOON.
THE THERMAL TROUGH REMAINS IN THE INTERIOR BUT SHOULD BEGIN TO SHIFT
SOUTHWARD LATE IN THE WEEK.

.MODEL DISCUSSION...
THE MODELS REMAIN IN GOOD SYNOPTIC AGREEMENT. THE BIGGEST DIFFERENCE
IS WITH SOME OF THE DETAILS REGARDING THE LARGE LOW THAT IS CURRENTLY
WELL SOUTH OF THE ALEUTIAN ISLANDS AND HEADING JUST SOUTH OF THE GULF
OF ALASKA THU AND FRI. THIS DIFFERENCES DEAL WITH THE ELONGATION OF
THE LOW ALONG THE FRONT AND POSSIBLE TRIPLE POINT LOW DEVELOPMENT.
HOWEVER SINCE THE LOW WILL REMAIN SOUTH OF THE GULF THE LARGEST
IMPACT ON FORECASTS WILL BE WITH THE WIND DIRECTION IN THE GULF
OFFSHORE MARINE AREA. NAM AND ECMWF ARE MORE AGGRESSIVE THAN THE GFS
IN DEVELOPING THE THERMAL TROUGH INTO THE COPPER RIVER BASIN AND
SUSITNA VALLEY THU AND FRI THAN THE GFS IS BUT THE THERMAL TROUGH
LOCATIONS ON THE NAM AND ECMWF ARE LIKELY CORRECT.

.SHORT TERM FORECAST...THE LOW IN THE GULF ARE PROVIDING PLENTY OF
MOISTURE AND LIFT TO BRING WIDESPREAD SHOWERS TO SOUTH CENTRAL ALASKA
THIS AFTERNOON. THESE SHOWERS SHOULD TAPER OFF OVERNIGHT AND BE JUST
ISOLATED TOMORROW AS THE ATMOSPHERE BECOMES MORE STABLE.
SOUTHWEST ALASKA IS ALREADY IN MORE STABLE CONDITIONS BUT THAT DID
HELP THE DEVELOPMENT OF FOG AROUND THE KUSKOKWIM DELTA THIS MORNING
AND THERE WILL PROBABLY BE MORE FOG DEVELOPING THROUGH THE MORNING
HOURS TOMORROW.
KODIAK ISLAND IS TAKING THE BRUNT OF THE SURFACE LOW AS IT CONTINUES
TO BRING RAIN TO THE AREA. CONDITIONS WILL IMPROVE AS THE LOW DRIFTS
NORTHEAST AND WEAKEN THROUGH TOMORROW MORNING.

.LONG TERM FORECAST...AN UPPER LEVEL RIDGE WILL BUILD OVER SOUTHWEST
ALASKA THU AND PUSH OVER SOUTH CENTRAL ALASKA BY FRIDAY. TEMPERATURES
ALOFT WILL WARM UP SOME BUT STILL REMAIN COOL ENOUGH TO ENCOURAGE
AFTERNOON AND EVENING SHOWERS. THESE WILL BE MOST NUMEROUS OVER
ELEVATED TERRAIN. THIS PATTERN SHOULD ALSO BRING IN WARMER
TEMPERATURES OVER THE REGION AND PERSIST THROUGH THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

JUN 13