Flood Watch 1, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
430 PM ADT TUE MAY 13 2008

.ANALYSIS AND UPPER LEVELS...
THE SURFACE LOW IS WEST OF SAINT PAUL WITH A TROUGH TO THE KUSKOKWIM
DELTA ACROSS THE ALEUTIAN MOUNTAINS TO KODIAK ISLAND. ANOTHER TROUGH
EXTENDS ACROSS THE INTERIOR FROM NORTON SOUND TO THE UPPER YUKON
VALLEY ALONG THE ARCTIC FRONTAL BOUNDARY. A RIDGE BUILDING BACK OVER
THE NORTH GULF COAST IS FURTHER WEAKENING THE REMNANTS OF THE FRONT
THAT MOVED ONSHORE YESTERDAY. THE UPPER LOW IS SLIGHTLY SOUTHWEST OF
THE SURFACE LOW AND THE UPPER TROUGH EXTENDS FROM THIS LOW ACROSS THE
KUSKOKWIM VALLEY AND THE CHUGACH MOUNTAINS INTO THE SOUTHERN YUKON
TERRITORY. ANOTHER MAJOR NORTH PACIFIC LOW IS RAPIDLY INTENSIFYING
ABOUT 660 NM SOUTH OF COLD BAY. MOISTURE FROM A TYPHOON NEAR JAPAN IS
BEING ENTRAINED IN THE UPPER JET AND FED INTO THIS LOW.

.MODEL DISCUSSION...
THE LAST TWO GFS RUNS HAVE FINALLY BEEN CONSISTENT WITH REGARD TO THE
INCOMING NORTH PACIFIC STORM. THERE ARE SOME MINOR DIFFERENCES IN THE
DEPTH AND LOCATION OF THIS LOW AS IT MOVES INTO THE GULF OF ALASKA
AND THIS AGREES WITH THE ENSEMBLE MEAN. THE MORE CONSISTENT MODEL
OUTPUT IS ALLOWING FOR HIGHER CONFIDENCE HOWEVER WE STILL HAVE SOME
CONCERN AS THIS LOW IS COMING FROM OUTSIDE THE MODEL DOMAIN AND HAS
SIGNIFICANT TROPICAL ENERGY ENTRAINED INTO IT. THE RIDGE THAT BUILDS
IN BEFORE THE LOW IS EXPECTED TO PRODUCE ISSUES IN THE FIRE WEATHER
REALM FOR THE SOUTH CENTRAL REGION AND COPPER RIVER BASIN TO THE
EASTERN KUSKOKWIM VALLEY.

.SHORT TERM FORECAST...
IN THE EAST RAIN AND SHOWERS WILL TAPER OFF ALONG THE GULF COAST AS
THE RIDGE BUILDS IN ADVANCE OF THE APPROACHING NORTH PACIFIC STORM
TONIGHT AND WEDNESDAY. EXPECT THE BUILDING RIDGE TO PRODUCE THE
STRONG SOUTH WIND ACROSS THE COPPER RIVER BASIN AND STRONG SOUTHEAST
CROSS BARRIER WIND IN THE NORTHERN COOK INLET TO MATANUSKA VALLEY
AREA THIS EVENING AND AGAIN WEDNESDAY. IT LOOKS LIKE THE WIND WILL
DROP OFF TONIGHT AS CLEARING CONDITIONS SHOULD ALLOW FOR THE
INVERSION TO FORM LATE TONIGHT. EXPECT THE INVERSION TO RAPIDLY BREAK
WEDNESDAY MORNING. THE NEXT PUSH OF WIND AND MOISTURE WILL ARRIVE
ALONG THE NORTH GULF COAST AND KODIAK ISLAND TONIGHT AND WE EXPECT
THE MAJORITY OF THE PRECIPITATION TO REMAIN ALONG THE COASTAL AREAS
AND SOUTHEAST EXPOSURES AS SOUTHEAST FLOW CAUSES DOWN SLOPING. FIRE
WEATHER CONCERNS WILL AGAIN BE AN ISSUE WEDNESDAY IN THE COPPER RIVER
BASIN AND MATANUSKA VALLEY TO THE ANCHORAGE AREA AS THE STRONG WIND
AND LOW HUMIDITY WILL COMBINE FOR DANGEROUS FIRE WEATHER CONDITIONS.
LATE WEDNESDAY THE LOW PUSH INLAND SPREADING CLOUDS AND COOLER MORE
HUMID CONDITIONS ACROSS THE EASTERN DOMAIN OF THE FORECAST AREA.

IN THE WEST SHOWERS WILL CONTINUE THROUGH WEDNESDAY OVER THE SW
MAINLAND UNDER THE UPPER TROUGH ALOFT. HOWEVER STRATIFORM CONDITIONS
ARE PREVALENT ALONG THE BERING SEA COAST AND BRISTOL BAY COAST BUT
EXPECT THOSE CONDITIONS TO IMPROVE LATE NIGHT TO THE EARLY MORNING
AS THE EAST OFFSHORE FLOW SETS UP IN ADVANCE OF THE INCOMING GULF
STORM. AS THE TROUGH AND LOW MOVE INTO THE INTERIOR THURSDAY WITH THE
WEAK TROUGH EXTENDING TO THE SOUTHWEST EXPECT THE MOISTURE TO MOVE
BACK INTO THE BERING SEA COASTAL AREAS AND INCREASING THE CHANCE OF
WIDESPREAD RAIN THURSDAY. RAIN AND SNOW SHOWERS WILL CONTINUE OVER
THE BERING AND ALEUTIAN CHAIN UNDER THE UPPER LOW THROUGH THE WEEK AS
THE UPPER LOW STAYS MAINLY STATIONARY OVER THE CENTRAL ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 130 132 138 140 150 155 175 176 351 352.
FIRE WEATHER...RED FLAG WARNING 111 141.

SAM MAY 08