Small Craft Advisory 402, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
211 PM AKDT TUE MAY 20 2014

.ANALYSIS AND UPPER LEVELS...
AN UPPER-LVL LOW CENTERED OVER THE NE GULF OF AK IS NEARLY STATIONARY.
A SURFACE LOW IS CENTERED 180 MILES SE OF MIDDLETON ISLAND AND DRIFTING
SOUTH. A RESIDUALLY SQUEEZED PRESSURE GRADIENT ASSOCIATED WITH IT IS
STILL PRODUCING SOME LOCALLY GUSTY WINDS AND RED FLAG CONDITIONS OVER
SOUTHCENTRAL/SW AK...THOUGH WEAKER COMPARED TO THE PAST COUPLE OF
DAYS. SOUTHCENTRAL AK AND KODIAK ISLAND REMAIN DRY IN THIS OFF-
SHORE FLOW. THERE IS A STRONG UPPER-LVL HIGH OVER THE CENTRAL
BERING SEA WHICH IS DRIFTING SLIGHTLY NORTHWARD. SOME WEAK
SHORTWAVE ENERGY HAS ROUNDED THE CREST OF THIS LARGE FEATURE INTO
NW AK AND IS DIPPING SOUTH. SOME INCREASED CLOUDS AND A FEW
PASSING SHOWERS NOTED ON SATELLITE AND RADAR IMAGERY POKING
THROUGH THE KUSKOKWIM DELTA. AN OLD CUT-OFF PACIFIC LOW UNDERNEATH
THE UPPER HIGH IS BEGINNING TO DRIFT NORTHEAST.

&&

.MODEL DISCUSSION...
ADEQUATE MODEL AGREEMENT FOR THE MOST PART ACROSS THE AOR. OF NOTE IS
THAT THE SURFACE LOW IN THE GULF HAS BEEN A BIT STRONGER AND
CLOSER IN PROXIMITY TO THE SOUTHERN MAINLAND THAN MODELS MIGHT
SUGGEST. MODELS SHOW THIS LOW DRIFTING TO AROUND 350 MILES SE OF
MIDDLETON ISLAND BY EARLY WED EVENING AND DISSIPATING AS IT MOVES
AWAY FROM THE PARENT UPPER-LOW OVER THE NE REACHES OF THE GULF.
THAT UPPER-LOW IS DEPICTED MEANDERING IN PLACE...REINFORCED AT
TIMES BY SHORTWAVE ENERGY DROPPING DOWN THE BACKSIDE OF THE
LONGWAVE TROUGH AND ENVELOPING THE OLD CUT OFF PACIFIC LOW PUSHING
NORTHEAST THE NEXT 24 TO 48 HOURS. BY FRI...MODELS SHOW A HIGH-ARCTIC
UPPER-LOW SNEAKING DOWN TOWARDS NE AK...WITH THE UPPER-LOW IN THE
NE GULF GETTING ABSORBED BY IT. A RESIDUAL UPPER-LOW IS SHOWN
LINGERING JUST SOUTH OF THE GULF OF AK...WITH SOUTHCENTRAL AK IN
THE THROAT OF THE GENERAL UPPER TROUGHING THAT BECOMES BROADER AND
COMPLEX IN SCOPE. OBVIOUSLY THERE ARE SOME DEVILS IN THE DETAILS
THAT NEED TO BE WEEDED OUT...BUT IN GENERAL THAT IS THE SPIRIT OF
THE MODEL TRENDS. FURTHER WEST...THE UPPER HIGH IN THE BERING
STILL IS DEPICTED DAMPENING AS UPSTREAM ENERGY FROM E ASIA WORKS
AGAINST IT. APPRECIABLE CHANGE TO THE OVERALL PATTERN HOWEVER DOES
NOT SEEM TO REALLY OCCUR UNTIL BEYOND FRIDAY HOWEVER OUT WEST.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
FEW CHANGES ARE EXPECTED TO THE MAINLY SUNNY AND DRY WEATHER PATTERN
OVER THE SOUTHERN MAINLAND. THE LOW IN THE GULF AS MENTIONED EARLIER
HAS BEEN STUBBORN TO MOVE AWAY AND WEAKEN...BUT SATELLITE IMAGERY DOES
INDEED SHOW IT ON THE MOVE SOUTHWARD. THIS WILL LOOSEN THE GRIP OF GUSTY
OUTFLOW WINDS. THOUGH A DEFINED SURFACE LOW WILL BE LACKING THE LATTER
PART OF WED INTO THU...THE GULF WILL STILL SEE RESIDUAL TROUGHING OF
SOME SORT PERSIST UNDER THE INFLUENCE OF TROUGHING/CYCLONIC FLOW
ALOFT. THIS WILL CONTINUE TO PROMOTE SOME DEGREE OF NORTH TO WEST
WIND FLOW...EXCEPT FOR AREAS THAT SEE TYPICAL SEABREEZES. WITH
REGARDS TO PRECIPITATION...PASSING RAIN SHOWERS ARE POSSIBLE FOR
THE COPPER RIVER BASIN AND OTHER AREA RANGES/MOUNTAINS ASSOCIATED
WITH WEAK UPPER DISTURBANCES EMBEDDED IN THE UPPER-FLOW AND SOME
INCREASED INSTABILITY AS LOW LEVEL TEMPERATURES WARM A BIT IN THE
COMING DAYS.

SOUTHWEST ALASKA...
THE PREDOMINANT OFF-SHORE FLOW GETS A BRIEF INTERRUPTION AS CLOUDS FROM
THE SHORTWAVE ENERGY TRAVERSE THE REGION. BUT LARGELY STARVED OF DEEP
MOISTURE...THESE WAVES WILL ALSO HELP PICK WINDS UP AGAIN. RED FLAG
POTENTIAL INDEED LOOMS LARGE AGAIN ON THU FOR ALL OF SW AK...INCLUDING
THE KUSKOKWIM DELTA WHICH HAS NOT BEEN WITHIN THE SCOPE OF CRITICAL
FIRE DANGER LEVELS IN THE MORE RECENT DAYS.

BERING SEA/ALEUTIANS/AKPEN...
PERSISTENT WEATHER FORECAST FOR THE BERING SEA AND CHAIN. THE DRY
AIR OVER SW AK HAS PROGRESSED FURTHER DOWN THE BERING SIDE OF THE
AKPEN...WITH THE CLEARING EDGE NEARING COLD BAY. THIS BREAK IN THE
CLOUDS MAY INDEED REACH THE EASTERN CHAIN AS THE ONSHORE FLOW GOES
MORE NE TO TAP INTO SOME OF THE DEEPER DRY AIR UPSTREAM. OTHERWISE...
PERSISTENT WEATHER FORECAST FOR THE BERING SEA/CHAIN WITH CONTINUED
FOG/STRATUS.

&&

.LONG TERM FORECAST...
THE LONG TERM FORECAST PERIOD IS CHARACTERIZED BY THE UPPER-HIGH/RIDGE
IN THE BERING SEA SLIDING EASTWARD. IT IS SHOVED MAINLY BY A PACIFIC/ASIA
LOW PRESSURE SYSTEM...THE CENTER OF WHICH TRACKS TO THE FAR WESTERN
ALEUTIAN CHAIN. THE RIDGING DAMPENS TO NEAR ZONAL FLOW AS IT REACHES
THE NORTHERN GULF/SOUTHCENTRAL AK...BECAUSE THE UPPER-LOW ON THE PERIPHERY
OF NORTHERN AK TRIES TO EXERT MORE INFLUENCE INTO THE STATE. AS THIS
PATTERN TRANSITIONS...GENERALLY EXUDING LOWER CONFIDENCE THAN USUAL
WITH REGARDS TO THE TIMING AND BREADTH OF INDIVIDUAL FEATURES.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...RED FLAG WARNING...111 121 141 145 161

&&

JAM