FXAK68 PAFC 251431
AFDAFC

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA         
500 AM AKST FRI DEC 25 2009

.ANALYSIS AND UPPER LEVELS...

CYCLONIC FLOW ASSOCIATED WITH A BROAD UPPER LEVEL LOW CENTERED ABOUT
500 MILES SOUTH OF THE ALASKA PENINSULA COVERS MUCH OF THE AREA OF
RESPONSIBLITY. A SECOND LOW CENTERED OVER THE KAMCHATCHKA PENINSULA
STRETCHES INTO THE BERING SEA. A WEAK UPPER LEVEL RIDGE NOSES INTO
THE SOUTHERN INTERIOR OF ALASKA FROM WESTERN CANADA. 

AT THE SURFACE...A LOW AT THE SURFACE IS STACKED UNDERNEATH THE UPPER
LEVEL LOW SOUTH OF CHIGNIK WITH MUCH OF THE AREA OF RESPONSIBILITY
EXPERIENCING THE ASSOCIATED CYCLONIC FLOW. A WEAK FRONT IS
PROGRESSING THROUGH THE GULF COAST BRINGING WIDESPREAD LIGHT TO
MODERATE PRECIPITATION. 

.MODEL DISCUSSION...

MODELS ARE IN GENERAL AGREEMENT IN THE SHORT TERM...HOWEVER THE
TIMING OF DISTURBANCES IN THE BROAD CYCLONIC FLOW IS PROVING
PROBLEMATIC BEYOND ABOUT 36 TO 48 HOURS. THE GFS IS CAPTURING THESE
SHORTWAVES FAIRLY WELL AND WAS THE MODEL OF CHOICE FOR THE MORNING
PACKAGE. 

.SHORT TERM FORECAST...

.SOUTHCENTRAL...A SERIES OF SHORTWAVES ASSOCIATED WITH THE NORTH
PACIFIC LOW WILL KEEP THE CHANCE OF PRECIPITATION AND CLOUDS ACROSS
THE REGION FOR THE NEXT FEW DAYS. HOWEVER...SOUTHEASTERLY DOWNSLOPE
FLOW IN THE ANCHORAGE BOWL AND WESTERN KENAI PENINSULA SHOULD LIMIT
PRECIPITATION. THE 12 UTC SOUNDING INDICATES A DEEP LAYER OF DRY AIR
OVER ANCHORAGE. HOWEVER...A SHORTWAVE IS EXPECTED TO MOVE ACROSS THE
AREA TODAY WHICH MAY HAVE ENOUGH MOISTURE TO BRING LIGHT 
PRECIPITATION EVEN TO TYPICAL DOWNSLOPE REGIONS IN ANCHORAGE
BOWL...WESTERN KENAI PENINSULA...AND MATANUSKA VALLEY. TEMPERATURES
ARE WARM ENOUGH ACROSS THE AREA THAT MIXED PRECIPITATION INCLUDING
FREEZING RAIN IS POSSIBLE WITH THIS SYSTEM. HOWEVER...AMOUNTS SHOULD
BE TOO LIGHT FOR ANY WORRIES ABOUT ISSUING AN ADVISORY. 

.SOUTHWEST...A SERIES OF SHORTWAVES WILL PROGRESS THROUGH THE REGION
OVER THE NEXT FEW DAYS BRINGING THE CHANCE FOR PRECIPITATION. 
HOWEVER...SOUTHEASTERLY DOWNSLOPE FLOW SHOULD KEEP NORTH AND WEST
FACING SLOPES RELATIVELY DRY. TEMPERATURES ARE WARM ENOUGH IN INLAND
LOCATIONS OF THE KUSKOKWIM VALLEY AND BRISTOL BAY REGIONS FOR THE
POSSIBILITY OF LIGHT MIXED PRECIPITATION...INCLUDING SOME FREEZING
RAIN. 

.ALEUTIANS...RELATIVELY QUIET CONDITIONS ARE EXPECTED ACROSS THE
REGION OVER THE NEXT FEW DAYS AS THE NORTH PACIFIC LOW REMAINS
RELATIVELY STATIONARY. LIGHT RAIN AND SNOW SHOWERS ARE POSSIBLE
ACROSS THE REGION DUE TO THE LOW BUT NO STRONG WINDS ARE EXPECTED. 

.LONG TERM FORECAST...THE STACKED LOW PRESSURE WITH BROAD CYCLONIC
FLOW ACROSS THE GULF AND NORTH PACIFIC IS PREDICTED TO PERSIST WELL
INTO NEXT WEEK AND SLOWLY WEAKEN. AS A RESULT...EXPECT HIGHER POPS
AND QPF ALONG THE COAST AS DISTURBANCES PASS BY. WINDS WILL LIKELY
REMAIN LIGHT OVER THE ALEUTIANS AND BERING SEA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE...120 130 132 155 
HEAVY FREEZING SPRAY WARNING...180 185

ELN/CC DEC 09