Small Craft Advisory 742, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT FRI SEP 16 2005

.DISCUSSION...

.ANALYSIS...0900Z ANALYSIS SHOWS BERING LOW IS NOW NEARLY STATIONARY
JUST TO THE SOUTH OF SAINT LAWRENCE ISLAND WITH OCCLUSION EXTENDING
ACROSS THE STATE FROM THE SEWARD PENINSULA TO JUST EAST OF MCGRATH
AND JUST EAST OF ILIAMNA TO JUST EAST OF KODIAK ISLAND WHERE A TRIPLE
POINT LOW IS DEVELOPING. THE FRONT WILL CONTINUE TO FALL APART AS IT
STRETCHES OUT AND MOVES FURTHER INLAND. RADAR SHOWS SHOWERS BEHIND
THE FRONT ACROSS SOUTHWEST ALASKA WITH AREAS OF RAIN OVER MUCH OF
SOUTHCENTRAL ALASKA. EVEN WITH A STRONG EAST-WEST GRADIENT BETWEEN
CORDOVA AND ANCHORAGE (7.1 MB) AND RESULTANT GAP WINDS ANCHORAGE AND
VICINITY HAVE BEEN RECEIVING STEADY RAIN DUE TO THE SOUTHERLY FLOW.
RADAR DOES SHOW A DRY SPOT OVER MUCH OF THE WESTERN KENAI. KENAI
RADAR VAD WIND PROFILE SHOWS LOW LEVELS WINDS BEGINNING TO BACK TO
THE SOUTHEAST. THIS TREND SHOULD CONTINUE AS LOW DEVELOPS TO THE
SOUTH AND PRECIP SHOULD CUT OFF OVER ANCHORAGE AND OTHER DOWNSLOPE
AREAS FOR A WHILE. BERING SEA AND ALEUTIANS ARE MOSTLY DRY WITH LOW
CLOUDS. A BROAD WESTERLY FLOW CONTINUES WITH WINDS GENERALLY
25 TO 35 KTS. SATELLITE IMAGERY CLEARLY SHOWS UPPER JET SOUTH OF
THE ALEUTIANS. A WEAK LOW IS LOCATED A FEW HUNDRED MILES SOUTH OF
THE WESTERN ALEUTIANS AND BEING PUSHED QUICKLY EASTWARD BY THE JET.

.MODEL ANALYSIS...NAM/GFS/UKMET ALL VERIFYING WELL TONIGHT AND
SOLUTIONS ARE REASONABLY CLOSE THROUGH 48 HOURS. THEY THEN DIVERGE
ON THE EVOLUTION OF THE LOW THAT TRACKS ACROSS THE GULF SATURDAY
AND SUNDAY. THE COMMON TREND IN THE MODEL SOLUTIONS IS FOR A DEEPER
LOW AND A MORE NORTHERLY TRACK TOWARD PRINCE WILLIAM SOUND. WITH
GOOD UPPER JET SUPPORT TO HELP WITH DEEPENING AND AN AMPLIFYING
TROUGH TO PULL THE LOW NORTHWARD BOTH OF THESE TRENDS MAKE SENSE.
WILL WATCH NEXT MODEL RUN CLOSELY TO SEE IF THESE TRENDS GO FURTHER.
FOR THIS FORECAST PACKAGE WILL GO WITH THE DEEPEST LOW AND A
COMPROMISE OF THE GFS/NAM TRACK.

.SHORT-TERM FORECAST...THE MOST SIGNIFICANT FEATURE TODAY IS THE
DEVELOPING TRIPLE POINT LOW EAST OF KODIAK ISLAND. THIS LOW WILL
DEEPEN SLIGHTLY AND SET UP GALE FORCE WINDS TO ITS EAST WITH THE
RIDGE OF HIGH PRESSURE ALONG THE NORTH GULF COAST HELPING TO REALLY
TIGHTEN UP THE PRESSURE GRADIENT. AS THE LOW MOVES TOWARD THE
SOUTHERN KENAI PENINSULA THIS MORNING EASTERLY FLOW ACROSS THE
PENINSULA WILL PROVIDE SOME DOWNSLOPING DRYING FROM THE MAT VALLEY
TO THE WESTERN KENAI WITH JUST SPRINKLES OR OCCASIONAL VERY LIGHT
RAIN. THE LOW WILL MOVE ONSHORE THIS AFTERNOON AND WINDS WILL
LIGHTEN UP AND THEN BECOME SOUTHWEST IN THE EVENING AS THE UPPER
TROUGH SWINGS NORTHEASTWARD. THIS EVOLUTION WILL BRING STEADY
RAIN UP COOK INLET AND THE WESTERN KENAI AND INTO ANCHORAGE AND
THE MAT VALLEY BY LATE AFTERNOON. SCATTERED SHOWERS WILL LINGER
INTO FRIDAY WITH THE NEXT SYSTEM ALREADY ON THE DOORSTEP. THE LOW
CURRENTLY SOUTH OF THE ALEUTIANS WILL RIDE ALONG THE UPPER JET
AFFECTING THE CENTRAL/EASTERN ALEUTIANS TODAY AND THE AKPENN
TONIGHT BEFORE MOVING INTO THE GULF SATURDAY. IT WILL BE A QUICK
SHOT OF RAIN ACCOMPANIED BY GALE FORCE WINDS. AS IT DEEPENS IN THE
GULF SATURDAY STORM FORCE WINDS ARE LIKELY. AS MENTIONED ABOVE WILL
NEED TO WAIT FOR THE NEW MODEL RUN TO TRY AND WORK OUT THE
DETAILS...BUT THE END OF THE WEEKEND LOOKS WET AND WINDY FOR MUCH
OF SOUTHCENTRAL ALASKA. MEANWHILE THE NORTHERN BERING LOW WILL
SLOWLY DRIFT INTO WESTERN ALASKA SUNDAY ACCOMPANIED BY WIDESPREAD
SHOWERS.

.EXTENDED FORECAST...AS NOTED THE PAST COUPLE DAYS THE EXTENDED
FORECAST PERIOD CONTINUES TO LOOK UNSETTLED WITH A VERY PROGRESSIVE
HEMISPHERIC WAVE PATTERN AND A SIGNIFICANT ZONAL JET MAINTAINING
ITS POSITION BETWEEN 45N AND 50N. THIS MAKES IT DIFFICULT TO
PINPOINT LOW TRACKS. THEREFORE...EXPECT A SHOT OF RAIN AND WINDS
EVERY FEW DAYS WITH LITTLE TIME FOR DRYING IN BETWEEN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 120 150 155 170 172 185.
FIRE WEATHER...NONE.

SEB SEP 05