Small Craft Advisory 494, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
600 AM ADT MON JUN 4 2007

.ANALYSIS AND UPPER LEVELS...THE MAIN FEATURES ON IR IMAGERY THIS MORNING ARE
THE LARGE LOW IN THE CENTRAL GULF OF ALAKSA WITH BROAD FRONTAL BAND/PRECIP
SHIELD MOVING ONSHORE ALONG THE GULF COAST...ANOTHER SURFACE LOW LOCATED JUST
SOUTH OF THE CENTRAL ALEUTIANS...AND FINALLY AN NORTH/SOUTH ELONGATED LOW
SITUATED UNDERNEATH A LARGE UPPER LOW IN THE WESTERN BERING. A STRONG 250MB JET
IS ALSO VISIBLE STREAMING ACROSS THE NORTH PACIFIC AT AROUND 40N.

.MODEL DISCUSSION...MODELS ALL SEEM TO HAVE THE BASIC GIST THROUGH THE FIRST 36
TO 48 HOURS. AFTER THAT POINT THE NAM ONCE AGAIN DIVERGES FROM THE GFS/UKMET.
WHEREAS THE GFS AND UKMET DEVELOP A DEEPER LOW ON THE NORTH SIDE OF THE JET THAT
ROTATES UP INTO THE WESTERN GULF...THE NAM DOES NOT DEVELOP THE LOW MUCH AND
INSTEAD SHUNTS IT RAPIDLY OFF TO THE EAST INTO THE PACIFIC NORTHWEST. THE GFS
HAS BEEN BEEN GOING WITH THIS STRONGER LOW FOR A COUPLE OF RUNS NOW...SO THE
FORECAST WILL BE GOING WITH THAT SOLUTION. MODEL AGREEMENT BETWEEN THE GFS AND
THE ECMWF IN THE EXTENDED IS ALSO ACCEPTABLE WITH BOTH MODELS INDICATING A BROAD
UPPER LOW OVER MAINLAND ALASKA AND THE GULF WITH RIDGING ACROSS THE WESTERN
BERING.

.SHORT TERM FORECAST...LARGE FRONT MAKES MOVES ASHORE ACROSS SOUTHCENTRAL TODAY
WITH RAIN SPREADING ACROSS THE COASTAL ZONES AND THE WESTERN KENAI THIS MORNING.
THE ANCHORAGE BOWL AND MATANUSKA VALLEY WILL BE IN AN AREA OF DOWNSLOPING AND
WILL PROBABLY SEE LITTLE IF ANY PRECIP WITH THIS SYSTEM. WINDS THROUGH PORTAGE
VALLEY AND TURNAGAIN ARM  SHOULD BE PICKING LATER THIS MORNING AS THE FRONT
MOVES THROUGH AND WILL CONTINUE AS A RIDGE BUILDS IN ALONG THE GULF COAST BEHIND
THE FRONT. EXPECT STRONGEST WINDS DURING INITIAL FRONTAL PASSAGE AND WITH
POST-FRONTAL ISALLOBARIC PUSH LATE THIS AFTERNOON INTO THE EVENING...HOWEVER
BREEZY CONDITIONS SHOULD CONTINUE THROUGH TUE NIGHT UNTIL THE CENTER OF THE
RIDGE MOVES OVERHEAD. THE UPWARD VERTICAL MOTION ASSOCIATED WITH THE FRONT AS IT
MOVE INLAND SHOULD ENHANCE SHOWER ACTIVITY OVER THE COPPER RIVER BASIN THIS
AFTERNOON...THOUGH SIGNIFICANT CLOUD COVER WILL PREVENT CONVECTION FROM BECOMING
DEEP ENOUGH FOR THUNDER THIS AFTERNOON. RAIN SPREADS INTO THE BRISTOL BAY REGION
LATE THIS AFTERNOON AND INTO THIS EVENING AS THE FRONT PUSHES RAPIDLY OUT AHEAD
OF THE PARENT LOW AND ACROSS THE KUSKOKWIM VALLEY LATER THIS EVENING. ONLY GOING
WITH CHANCE POPS FOR THE KUSOKWIM VALLEY ZONES TONIGHT THOUGH AS MUCH OF THE
MOISTURE WITH THE FRONT IS LIKELY TO HAVE PRECIPITATED OUT.

RIDGING IN THE WAKE OF THE LOW WILL BRING A BRIEF RESPITE FOR MOST OF
SOUTHCENTRAL WITH SUNNIER SKIES TUE INTO WED...THOUGH SHOWERS WILL LINGER ALONG
THE EASTERN KENAI AND KODIAK ISLAND IN THE EASTERLY SURFACE FLOW. THE NEXT
SYSTEM ARRIVES IN THE WESTERN GULF WED NIGHT...BRINGING ANOTHER BOUT OF GALES TO
THE WESTERN GULF AND KODIAK ISLAND AND PRECIP TO THE COASTAL AREAS ONCE AGAIN
AND WIDESPREAD SHOWER ACTIVITY INLAND AMD ACROSS THE KUSKOKWIM VALLEY ON THU.

IN THE BERING SEA AND ALEUTIANS...THE LOW IN THE CENTRAL ALEUTIANS WILL BRING
WIDESPREAD RAIN. THIS LOW MERGES WITH THE SYSTEM THAT IS DROPPING DOWN ACROSS
THE WESTERN BERING...BRINGING UNSETTLED WEATHER TO THE WESTERN AND CENTRAL
BERING THROUGH WED. RIDGING BUILDS ACRSS THE WESTERN BERING ON WED AS THE
CONSOLIDATED LOW SLOWLY MOVES EAST.

.LONG TERM FORECAST...THE GENERAL PATTERN BY THE LATTER PART OF THE WEEK IS FOR
A BROAD UPPER LOW ACROSS MAINLAND ALASKA AND THE GULF WITH WEAK SURFACE RIDGING
ACROSS THE CENTRAL AND WESTERN BERING/ALEUTIANS. COASTAL AREAS OF THE GULF WILL
CONTINUE TO BE IN A WET PATTERN BUT INLAND ZONES ACROSS SOUTHCENTRAL SHOULD SEE
WARMER DRIER WEATHER BY THE WEEKEND AS THE FLOW BECOMES EASTERLY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 130.
FIRE WEATHER...NONE.

WOOD JUN 07