Areal Flood Warning 13, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
405 AM AKDT FRI JUL 18 2008

.MODEL DISCUSSION...MODELS IN GOOD AGREEMENT THIS MORNING WITH DECENT
RUN-TO-RUN CONSISTENCY. ONLY MINOR ADJUSTMENTS NEEDED WITH A BLEND
TOWARD THE 00Z GFS.

.ANALYSIS AND UPPER LEVELS...SATELLITE SHOWS THE LOW AND ASSOCIATED
OCCLUSION THAT HAVE BEEN PLAGUING THE MAINLAND FOR THE LAST FEW DAYS
SITTING JUST SOUTH OF NUNIVAK ISLAND ON THE Y-K DELTA COAST. IT HAS
BECOME MORE LOOSELY WRAPPED AS A TRIPLE POINT LOW INTENSIFIED OVER
WESTERN PRINCE WILLIAM SOUND. EXPECT THIS SECOND LOW TO PUSH INLAND
AND DISSIPATE TODAY. THE OCCLUDED FRONT AND THE SECONDARY FRONT ARE
PUSHING EASTWARD AND INLAND OVER THE NORTHEAST GULF AND ACROSS THE
SUSITNA AND COPPER RIVER VALLEYS. A DEFORMATION ZONE HAS SET UP FROM
THE SOUTHERN SUSITNA VALLEY TO SEWARD AND IS PRODUCING HEAVY RAINFALL
ACROSS A THIN BAND OF THE KENAI PENINSULA. TROUGHS AND UPPER LEVEL
LOWS SHOULD REMAIN OVER THE MAINLAND THROUGH EARLY NEXT WEEK.
A STRONG EAST TO SOUTHEAST MOVING JET IS STILL JUST ALONG AND SOUTH
OF THE ALEUTIANS. OKMOK VOLCANO CONTINUES TO PRODUCE VERY LIGHT ASH
OVER A NARROW AREA OF THE EASTERN ALEUTIANS.

.SHORT TERM FORECAST...
SOUTHCENTRAL...RAIN WILL HANG IN FOR MOST OF SOUTHCENTRAL THROUGH THE
DAY FRIDAY WITH SOME IMPROVEMENT POSSIBLE FRIDAY NIGHT AS THE MAIN
LOW BACK OVER WESTERN ALASKA TRANSITIONS INTO THE GULF. HOWEVER...THE
UPPER LEVEL LOW COMPLEX WILL REMAIN OVER THE REGION THROUGH AT LEAST
SATURDAY RESULTING IN A SHOWERY PATTERN. BY SUNDAY ANOTHER TROUGH
WILL SWING IN FROM THE NORTHWEST...SO DONT EXPECT MUCH OF A BREAK IN
THE WEATHER.

SOUTHWEST ALASKA/ALASKA PENINSULA...THE WESTERN ALASKA LOW WILL
SLOWLY SINK SOUTHEASTWARD AND DISSIPATE NEAR THE KILBUCK MOUNTAINS
FRIDAY EVENING AS THE UPPER LEVELS OPEN TO A TROUGH AND SWING INTO
THE GULF. RAIN/SHOWERS ALONG WITH LOW CLOUDS AND FOG ALONG THE COAST
WILL CONTINUE INTO FRIDAY WITH A DRYING TREND BEGINNING LATE FRIDAY.
SATURDAY LOOKS LIKE A BRIEF RESPITE FROM WET WEATHER AS A TRANSIENT
SHORT-WAVE RIDGE MOVES THROUGH...BUT NEXT TROUGH WILL SWING DOWN
FROM THE NORTH ON SUNDAY BRINGING A RETURN TO RAIN.

BERING SEA/ALEUTIANS...THE LOW SOUTH OF THE WESTERN ALEUTIANS WILL
MOVE FAR ENOUGH SOUTH OF ALEUTIANS THIS MORNING TO CLEAR OUT ALL
OF THE RAIN. WEAK HIGH PRESSURE WILL THEN BUILD OVER THE WESTERN
ALEUTIANS FRIDAY AND HOLD IN ON SATURDAY AND SUNDAY AS A PACIFIC
SYSTEM APPROACHES FROM THE SOUTHWEST.

.LONG TERM FORECAST...
COOL MOIST AIR WILL REMAIN IN PLACE ACROSS SOUTHCENTRAL THROUGH NEXT
WEEK. POSSIBLE BREAKS ON SATURDAY BEFORE MORE RAIN MOVES IN EARLY
NEXT WEEK AS AN UPPER LEVEL LOW PUSHES DOWN INTO SW AK. FOG AND
STRATUS WILL HOLD OUT ACROSS THE WESTERN AND CENTRAL BERING INTO NEXT
WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...ASHFALL ADVISORY 185.
MARINE...ASHFALL ADVISORY 170.
FIRE WEATHER...NONE.

RNW JUL 08