Flood Watch 3, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT FRI SEP 5 2008

.MODEL DISCUSSION...GFS MODEL OVERALL APPEARS TO BE THE MOST
REASONABLE AND CONSISTENT WITH DEVELOPING STORM SYSTEM WHICH MOVES TO
THE AK PEN SAT. ECMWF IS A CLOSE SECOND. MODELS TEND TO STRUGGLE SOME
WITH INTENSITY AND POSITION OF NEXT LOW COMPLEX TO IMPACT THE AK PEN
MON. THE TREND OF THE GFS AND ECMWF HAS BEEN TO WEAKEN THE LOW
COMPLEX.

.UPPER LEVELS...HEIGHTS RISE OVER THE MAINLAND AND GULF OF ALASKA
TONIGHT AS THE LOW OVER THE NORTHEAST PACIFIC INTENSIFIES AND TRACKS
NORTH TOWARD THE AK PEN. BY SAT EVENING...A LOW COMPLEX IS EVIDENT
OVER THE AK PEN/EASTERN BERING SEA WITH A RIDGE EXTENDING FROM 40N
135W TO OVER THE MAINLAND. THE RIDGE FLATTENS SUN/MON AS THE TROUGH
FROM THE EASTERN BERING SEA STRETCHES EAST/NE TO OVER THE MAINLAND.
THE RIDGE BUILDS OVER THE WESTERN BERING SEA/EASTERN RUSSIA SUN/MON
AS THE TROUGH DIGS FROM CENTRAL RUSSIA TO JAPAN.

.SURFACE FORECAST...
HIGH PRESSURE BUILDS OVER THE GULF OF ALASKA AND EASTERN MAINLAND
TONIGHT THEN RETREATS EAST SAT. DEVELOPING NE PACIFIC LOW CENTER
MOVES TO JUST SOUTH OF THE AK PEN SAT EVENING AND INTENSIFIES TO 985
MB. THEN CENTER THEN CROSSES THE AK PEN INTO BRISTOL BAY AND WEAKENS
SUN MORNING. THIS LOW CONTINUES WEAKENING TREND AND TRACKS INTO THE
INTERIOR SUN NIGHT AS THE RIDGE REBUILDS OVER THE GULF OF ALASKA.
ASSOCIATED FRONTAL TROUGH IMPACTS THE SOUTHERN COAST OF THE AK PEN
AND KODIAK ISLAND SUN MORNING. BY SUN EVENING...THE FRONT EXTENDS
FROM THE WESTERN AK PEN...SW AK...KENAI PEN...TO SOUTH ALONG 147W. BY
SUN AFTERNOON...THE FRONT MOVES INTO THE CENTRAL INTERIOR AND THE
EASTERN GULF.

.EAST...EXPECT UPPER SHORT WAVE MOVING THROUGH SOUTHCENTRAL THIS
AFTERNOON AND EVENING WILL CONTINUE SHOWERS OVER MANY AREAS. SURFACE
RIDGE BUILDS IN AFTER MIDNIGHT...SO WILL SEE AREAS OF FOG AND LOW
STRATUS. EXPECT PRESSURE GRADIENTS TO INCREASE OVER THE THE GULF OF
ALASKA AND SOUTHCENTRAL SAT WITH APPROACH OF LOW CENTER AND
ASSOCIATED FRONTAL TROUGH. THE RESULT WILL BE STRONG WINDS OVER MUCH
OF THE GULF SAT AND SAT NIGHT WITH STORM FORCE WINDS OVER SHELIKOF
STRAIT AND THE BERING SEA. GAP WINDS OVER SOUTHCENTRAL LIKELY TO BE
FAIRLY STRONG AND WILL REQUIRE HEADLINES. WINDS WILL DIMINISH OVER
THE GULF SUN AS THE FRONT WILL HAVE MOVED INLAND AND TO THE EASTERN
GULF. GAP WINDS...THOUGH NOT AS STRONG...WILL REMAIN BRISK OVER
SOUTHCENTRAL INTO EARLY MON. LOCALLY HEAVY RAIN POTENTIAL (2 INCHES
OR MORE) EXISTS OVER THE EASTERN KENAI PEN SAT NIGHT AND SUN AS THERE
IS A DEEP AND MOIST SOUTHERLY FETCH ASSOCIATED WITH THE FRONTAL
TROUGH. FOR NOW WILL GO WITH A FLOOD WATCH AND SEE HOW THINGS SHAPE
UP.

.WEST...GENERALLY WILL SEE SHOWERS INLAND WITH STRATUS AND FOG ALONG
COASTS TONIGHT. EXPECT RAIN TO SPREAD TO SW ALASKA SAT AND BREAK UP
MORE INTO SHOWERS SUN. DOWNSLOPE OVER INTERIOR SW AK WILL KEEP RAIN
TO MINIMUM SAT. STRONG GALE TO STORM FORCE IN ADVANCE OF FRONTAL
TROUGH AS IT IMPACTS THE AK PEN LATE TONIGHT/SAT. WINDS WILL SPREAD
TO BRISTOL BAY THROUGH SAT. BY SUN AFTERNOON...WINDS OVER MOST AREAS
WILL HAVE DIMINISHED CONSIDERABLY. HOWEVER...STRONG SW WINDS ARE
LIKELY SOUTH OF THE AK PEN. HIGH PRESSURE GENERALLY HOLDS OVER THE
CENTRAL BERING SEA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...UPCOMING FLOOD WATCH FOR ZONE 125
MARINE...STORMS 138 AND 155. GALES 121 125 130 132 140 150 160 165.
FIRE WEATHER...NONE.

RMC SEP 08