Fire Weather Watch 1, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT TUE MAY 8 2012

.ANALYSIS AND UPPER LEVELS...A LOOK AT THE MORNING WEATHER MAP
CONTINUES TO SHOW A LARGE UPPER TROUGH CENTERED OVER THE ALASKA
REGION...WITH A CLOSED LOW IN THE FAR SOUTHERN GULF. AS THIS LOW
MOVES TO THE NORTHEAST THE OVERALL TROUGH IS LOSING
AMPLITUDE...CREATING INCREASINGLY ZONAL FLOW OVER THE ALEUTIANS. A
BROAD AREA OF LOW PRESSURE AT THE SURFACE IN THE EASTERN GULF IS
PUSHING INLAND ALONG THE NORTHEAST GULF COAST. A STRONG SHORTWAVE IS
VISIBLE ON SATELLITE IMAGERY APPROACHING THE COPPER RIVER BASIN WITH
A SUBSTANTIAL CLOUD SHIELD AND STEADY/STRATIFORM RAIN. WEAK HIGH
PRESSURE BUILDING OVER THE CENTRAL ALEUTIANS IS LEADING TO LIGHT
SOUTHWEST FLOW OVER THE BRISTOL BAY AND DELTA AREAS...WHICH IS
COMBINING WITH ABUNDANT LOW LEVEL MOISTURE TO PRODUCE AREAS OF FOG
AND STRATUS IN THE REGION. FURTHER WEST...AN UPPER LEVEL SHORTWAVE
THAT DROPPED OFF THE KAMCHATKA PENINSULA IS OVER THE WESTERN BERING
AND IS SUPPORTING A RELATIVELY WEAK 1000 MB SURFACE LOW NORTHWEST OF
ADAK. THIS IS BRINGING AN AREA OF RAIN AND GUSTY WINDS TO THE WESTERN
HALF OF THE ALEUTIANS THIS MORNING.

.MODEL DISCUSSION...MODELS ARE IN FAIRLY GOOD AGREEMENT THIS MORNING
WITH THE MAIN FEATURES. THE 00Z NAM IS A NOTABLE OUTLIER...TRYING TO
SPEED THE BERING LOW TO THE EAST QUICKER THAN THE CONSENSUS OF THE
OTHER MODELS. THE NAM IS ALSO AN OUTLIER ON THE HANDLING OF THIS LOW
ONCE IT ARRIVES OVER SOUTHWEST ALASKA. THE NAM FAVORS A NORTHWARD
MOVEMENT AND ELONGATION OF THE LOW CENTER WHILE THE EC AND GFS KEEP A
CONSOLIDATED CENTER IN THE VICINITY OF BRISTOL BAY. THE EC AND GFS
WERE FAVORED FOR THE MORNING FORECAST...WITH INCREASING PREFERENCE
TOWARD HPC FOR DAYS 4 THROUGH 7.

.SHORT TERM FORECAST...
SOUTHCENTRAL...MAIN FORECAST CHALLENGE TODAY WILL BE STRATIFORM
PRECIPITATION SHIELD ASSOCIATED WITH EASTERLY WAVE IN THE COPPER
RIVER BASIN TODAY. OVERNIGHT MODELS HAVE COME INTO GOOD AGREEMENT
THAT THE BULK OF THE PRECIPITATION WILL STAY IN THE EASTERN
TWO-THIRDS OF THE COPPER BASIN...ALSO LIKELY AFFECTING VALDEZ AND
CORDOVA. THIS SHOULD FALL PRIMARILY AS RAIN AT LOWER
ELEVATIONS...WITH MORE OF A MIX THROUGH THE HIGHER ELEVATION MOUNTAIN
PASSES. WHILE THE STEADY RAIN STAYS EAST OF ANCHORAGE AND THE MAT-SU
VALLEY...THERE SHOULD BE ENOUGH SUN FOR DIURNAL SHOWER ACTIVITY AGAIN
TODAY FROM THE TALKEETNA MOUNTAINS TO THE KENAI MOUNTAINS. SHOULD
ALSO SEE SOME DECENT SEA BREEZES AROUND SOUTHCENTRAL TODAY AS WEAK
FLOW AND SOME SUNSHINE ALLOW THE LAND TO WARM UP QUICKER THAN THE
WATER. ON WEDNESDAY...THE LOW CURRENTLY OUT WEST WILL SLOW DOWN AS IT
APPROACHES THE SOUTHWEST GULF. THIS WILL BRING STEADY RAIN TO KODIAK
ISLAND...WITH DIURNAL SHOWER ACTIVITY CONTINUING OVER THE REST OF
SOUTHCENTRAL.

.SOUTHWEST...MAIN CHALLENGE WILL BE LOW CLOUDS AND FOG AROUND THE
AREA...ESPECIALLY BRISTOL BAY AND THE DELTA. DAYTIME HEATING INLAND
MAY CAUSE SOME OF THE FOG TO LIFT TO LOW STRATUS...BUT PERSISTENT
ONSHORE FLOW SHOULD KEEP THE CLOUDS AROUND FOR MUCH OF THE DAY. ON
WEDNESDAY THE ALEUTIAN LOW WILL TAKE UP A POSITION SOUTH OF THE
ALASKA PENINSULA. THIS WILL REVERSE THE WINDS TO OFFSHORE WHICH
SHOULD MOVE THE LOW CLOUDS BACK OUT TO SEA. MEANWHILE...A RAIN/SNOW
MIX WILL BE LIKELY DURING THE DAY WEDNESDAY ACROSS BRISTOL BAY AS THE
LOW CENTER SLOWS TO A CRAWL NEAR CHIGNIK.

.BERING SEA AND ALEUTIANS...1001 MB LOW CENTER NORTH OF ADAK WILL
SLOWLY STRENGTHEN AS SYSTEM SLIDES EAST THROUGH WEDNESDAY. NOT AN
OVERLY WELL-ORGANIZED LOW...WITH RAGGED/ELONGATED APPEARANCE NOTED ON
SATELLITE. MAIN IMPACTS WILL BE A  PERIOD OF RAIN/SNOW PRECEDING THE
ARRIVAL OF THE LOW...WITH A BRIEF PERIOD OF NEAR-GALE FORCE WINDS AS
THE SYSTEM MOVES AWAY. THE REGION GOES BACK INTO A COOL NORTHERLY
FLOW REGIME WITH SNOW SHOWERS BEGINNING WEDNESDAY AND LASTING THROUGH
THE END OF THE WEEK.

.LONG TERM FORECAST...
MODELS IN LOOSE AGREEMENT THAT ANOTHER UPPER LOW WILL DROP DOWN THE
WEST COAST OF ALASKA NEAR THE END OF THE WEEK BRINGING A REINFORCING
SHOT OF COLD AIR TO THE EASTERN BERING AND SOUTHWEST
MAINLAND...CONTINUING THE LONGWAVE TROUGH ENCOMPASSING THE STATE.
HOWEVER...BY THE START OF NEXT WEEK THE MODELS ARE ALSO BEGINNING TO
SUGGEST A LOW AMPLITUDE NORTH PACIFIC RIDGE DEVELOPS AND BRINGS DEEP
SOUTHWEST FLOW TO MUCH OF THE MAINLAND. IF TRUE...SUCH A PATTERN
TENDS TO BRING CLOUDCOVER AND STRATIFORM RAIN TO BOTH INLAND AND
COASTAL LOCATIONS IN SOUTHERN ALASKA. UNTIL THEN...EXPECT CONTINUED
NEAR-NORMAL TEMPERATURES WITH DIURNAL SHOWERS INLAND AND MORE
PERSISTENT RAIN OR SHOWERS ALONG THE GULF COAST.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WARNING 152
MARINE...GALE 130 132 172 176 179
FIRE WEATHER...NONE

DIXON MAY 12