Small Craft Advisory 336, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM ADT TUE APR 10 2007

.DISCUSSION...GENERALLY QUIET WEATHER WITH THE CURRENT SATELLITE
IMAGERY SHOWING CLOUDY SKIES OVER MOST OF THE NORTH GULF COAST AND
SOUTHCENTRAL MAINLAND THIS AFTERNOON...RADAR/OBS INDICATING RAIN
SHOWERS OVER THE NORTH GULF COAST AND THE SOUTHWEST MAINLAND ATTM.
THESE CLOUDS AND SHOWERS ARE ASSOCIATED WITH A WEAK SLOW-MOVING LOW
PRESSURE SYSTEM OVER BRISTOL BAY THAT WILL CONTINUE TO WRAP ONSHORE
FLOW WITH CLOUDS AND SHOWERS INTO SOUTHCENTRAL ALASKA. A VERY WEAK
RIDGE BUILDS INTO SOUTHEAST ALASKA AND THE SOUTHCENTRAL MAINLAND
WEDNESDAY BEFORE ANOTHER NORTH PACIFIC LOW SOUTH OF THE ALASKA
PENINSULA MOVES EAST TO AFFECT THE GULF OF ALASKA BY THE END OF THE
WEEK.

.MODELS...ALL SOLUTIONS SEEM TO BE A BIT MORE PROGRESSIVE WITH THE
TIMING OF THE LOW APPROACHING THE GULF. THE LAST TWO GFS AND NAM
MODEL RUNS HAVE THE NORTH PACIFIC LOW MOVING INTO THE GULF THURSDAY
WHILE THE ECMWF/UKMET CONTINUE TO BE THE FASTER...MOVING THE LOW INTO
THE GULF WEDNESDAY NIGHT.

 BECAUSE OF THIS QUICKER TREND TO USHER THE SYSTEM TO THE
EAST WE CONTINUE TO THINK THE SYSTEM MIGHT NOT HAVE MUCH OF AN EFFECT
ON SOUTHCENTRAL WEATHER AS IT STAYS TO OUR SOUTH AND THAT THE
SOUTHEAST PANHANDLE WILL FEEL THE BRUNT OF THE STORM LATER THIS WEEK.
THE ENSEMBLE MEAN DEPICTS THE SYSTEM AS BEING SIGNIFICANTLY WEAKER
THAN THE OPERATIONAL SOLUTIONS...MOST LIKELY BECAUSE OF THE WIDE
DISPARITY IN THE ENSEMBLE MEMBERS IN BOTH TRACK AND STRENGTH. BOTH
DOMAINS HAVE TRENDED TOWARDS THE GFS SOLUTION WITH LITTLE TWEAKING OF
THE EXTENDED GRIDS.

.SOUTH AND EAST OF THE ALASKA RANGE...AS THE DECAYING LOW IN BRISTOL
BAY CONTINUES TO WEAKEN AND EDGE SLOWLY TO THE WEST...A 140KT JET
ALONG 40N SWEEPS UP THE ABOVE-MENTIONED LOW AND CARRIES IT EAST INTO
THE GULF. WEAK ONSHORE FLOW IS EXPECTED TO PERSIST THROUGH MID WEEK
OVER SOUTHCENTRAL ALASKA...WITH CLOUDS AND SOME SHOWERS IN THE USUAL
COASTAL FAVORED AREAS. KODIAK AND THE SOUTHERN ALASKA PENINSULA LOOK
TO HAVE THE BEST SHOT AT GETTING SOME WIND AND RAIN FOR THE LOW
TRACKING WEST TO EAST ACROSS THE GULF MID WEEK. WEAK RIDGING COULD
ALLOW SOME CLOUD BREAKS OVER SOUTHCENTRAL LATE WEDNESDAY INTO THE END
OF THE WORK WEEK. FREEZING LEVELS HAVE BEEN LOWERING THE LAST SEVERAL
DAYS AS SUBTLE COLD ADVECTION DRAINS SOUTH CREATING THE POSSIBILITY
FOR SNOW SHOWERS DEVELOPING OVER THE HIGHER TERRAIN. THERE IS A
CHANCE OF SOME HEAVIER CONVECTION OVER HIGHER TERRAIN THURSDAY AS THE
ATMOSPHERE BECOMES LESS STABLE DUE TO COOLING ALOFT AND BREAKS IN THE
CLOUDS WARMING THE SURFACE. HOWEVER THIS IS JUST A CHANCE AT THIS
TIME SINCE THE WEAK RIDGING THAT WILL PRODUCE THE CLOUD BREAKS WILL
PROBABLY BE ENOUGH TO DIMINISH THE CONVECTIVE POTENTIAL.

.WEST OF THE ALASKA RANGE AND THE ALEUTIANS...A WEAK UNSETTLED
PATTERN WILL PERSIST OVER THE SHORT TERM WITH CLOUDS AND SCATTERED
RAIN AND SNOW SHOWERS OVER THE SOUTHWEST CAPES AND ALEUTIANS THROUGH
TUESDAY. WITH THE NORTH PACIFIC LOW LOOKING TO TRACK MORE ZONAL THAN
PREVIOUSLY THOUGHT THE WIND THREAT LOOKS TO MAINLY CENTER ON THE FAR
EASTERN ALEUTIAN ISLANDS AND ALASKA PENINSULA. WRAP AROUND MOISTURE
OVER THE SOUTHWEST CAPES SHOULD CONTINUE AFFECT THE CENTRAL AND
EASTERN ALEUTIANS THROUGH THE WEEK.

.EXTENDED...THE CURRENT THREE WAVE HEMISPHERIC PATTERN LOOKS TO
TRANSITION INTO A SPRING-TIME PATTERN OF SHORTENED WAVELENGTHS OVER
NORTHERN PORTIONS OF THE WESTERN HEMISPHERE. OVER THE NORTHERN
PACIFIC THE STORM TRACK LOOKS TO STAY ANCHORED OVER 50N AND LOOKS TO
CONTINUE THE UNSETTLED WEATHER ACROSS MUCH OF THE STATE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 150 155.
FIRE WEATHER...NONE

MCKIM/EZ APR 07