Flood Watch 3, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AKDT MON JUL 20 2009

.ANALYSIS AND UPPER LEVELS...
A VERTICALLY STACKED UPPER LEVEL LOW CONTINUES TO INTENSIFY IN THE
LONGWAVE TROUGH OVER THE BERING SEA. DEVELOPMENT OF THIS LOW IS BEING
AIDED BY A 130 KT JET ALOFT. A RIDGE THAT EXTENDS INTO THE EASTERN
NORTH SLOPE REGION CONTINUES TO PROPAGATE EASTWARD.

.SURFACE...A 981 LOW IS LOCATED JUST TO THE NORTH OF DUTCH HARBOR
DIRECTLY UNDERNEATH THE UPPER LEVEL LOW. LATEST SHIP REPORTS AND
STATION OBSERVATIONS ARE ALREADY INDICATING WINDS OVER 40KTS WITHIN
THE REGION.  RAIN IS BEING REPORTED ACROSS THE PRIBILOFS AND DUTCH
HARBOR. IN THE CENTRAL GULF OF ALASKA A TROUGH IS GENERATING NUMEROUS
SHOWERS.  FURTHER WEST A FRONT ASSOCIATED WITH THE BERING LOW IS
MOVING THROUGH THE WESTERN GULF OF ALASKA.

.SHORT TERM FORECAST...

.SOUTHCENTRAL...GALE FORCE WINDS ASSOCIATED WITH THE BERING LOW WILL
BEGIN TO EFFECT MUCH OF THE GULF...PRINCE WILLIAM SOUND...AND COOK
INLET TUESDAY AFTERNOON. RELATIVELY UNUSUAL FOR THIS TIME OF
YEAR...STORM FORCE WINDS ARE EXPECTED IN THE VICINITY OF THE BARREN
ISLANDS TODAY. TURNAGAIN ARM WINDS WILL REMAIN VERY STRONG THROUGH
WEDNESDAY MORNING. ALONG THE CENTRAL GULF COAST WINDS WILL WEAKEN
SLIGHTLY BUT REMAIN STRONG THROUGH WEDNESDAY AFTERNOON. ONSHORE FLOW
WILL KEEP PRECIPITATION ALONG THE COAST EVEN AFTER THE TROUGH HAS
PASSED THROUGH TUESDAY MORNING.  HEAVIER PRECIPITATION WILL APPROACH
THE COAST TUESDAY AFTERNOON AS A POTENT FRONT ASSOCIATED WITH THE
BERING LOW APPROACHES THE GULF COAST. PRECIPITATION WILL BEGIN TO
DECREASE AS THIS FRONT BREAKS APART ALONG THE COAST WEDNESDAY
AFTERNOON.

.SOUTHWEST...
WINDS NEAR GALE FORCE ARE ALREADY OCCURRING ACROSS THE ALASKA
PENINSULA AND ALONG BRISTOL BAY. NEAR GALE FORCE WINDS WILL OCCUR
ACROSS THE REGION THROUGH TUESDAY AFTERNOON. AS THE LOW APPROACHES
EXPECT WIDESPREAD RAIN ACROSS THE AREA THROUGHOUT THE DAY TUESDAY.
SHOWERS WILL LINGER ALONG BRISTOL BAY THROUGH WEDNESDAY EVENING.

.BERING AND ALEUTIANS...
GALE WINDS ON THE BACK SIDE OF THE LOW WILL IMPACT THE CENTRAL AND
EASTERN ALEUTIAN ISLANDS THROUGH WEDNESDAY MORNING. WIDESPREAD RAIN
WILL OCCUR ALONG THE CENTRAL AND EASTERN ALEUTIAN ISLANDS THROUGH
WEDNESDAY AS THE BERING LOW CONTINUES TO PROGRESS SLOWLY EASTWARD.

.LONG TERM FORECAST...
THE INTENSE BERING LOW WILL BEGIN TO WEAKEN AND RETROGRADE BY THE END
OF THE WEEK AS A STRONG UPPER LEVEL RIDGE BUILDS INTO THE EASTERN
PART OF THE STATE. PRECIPITATION ASSOCIATED WITH THE RETROGRADING LOW
WILL CONTINUE TO IMPACT THE WESTERN PORTION OF THE STATE. MANY AREAS
EAST OF THE ALASKA RANGE SHOULD BEGIN TO DRY OUT...WITH THE EXCEPTION
OF THE NORTH GULF COAST WHERE ONSHORE FLOW WILL CONTINUE TO BRING
SHOWERS TO MOST AREAS.

.MODEL DISCUSSION...
MODELS ARE RELATIVELY CONSISTENT IN THE PLACEMENT AND INTENSITY OF
THE BERING LOW.  MODELS ARE ALSO CONSISTENT IN THE LOCATION AND
INTENSITY OF THE ASSOCIATED AREAS OF STRONG WINDS. THE NAM WAS USED
FOR CENTRAL ALASKAN WINDS DUE TO HIGHER RESOLUTION AND BETTER
HANDLING OF TERRAIN EFFECTS. MODELS BEGIN TO DIVERGE IN THE LOCATION
OF THE BERING LOW BEGINNING THURSDAY AFTERNOON WITH THE GFS PREFERRED
FOR ITS MIDDLE-OF-THE-ROAD SOLUTION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM 130
         GALE 120 125 129 132 136 137 138 140 141 150 155 160 170 171
              172 179 180
FIRE WEATHER...NONE.

ELN JUL 09