Small Craft Advisory 14, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST SAT JAN 3 2009

.ANALYSIS AND UPPER LEVELS...
A VERY STABLE PATTERN PERSISTS ACROSS ALASKA. THE OMEGA BLOCKING
RIDGE LOCATED OVER THE CENTRAL AND EASTERN BERING SEA IS BECOMING
PINCHED OFF BY TWO LARGE UPPER LEVEL LOWS...ONE OVER MAINLAND ALASKA
AND A SECOND SOUTHEAST OF THE KAMCHATKA PENINSULA. SOUTH OF THE
ALEUTIANS IS A 170 KT JET FLOWING OUT OF A LARGE UPPER TROF OVER THE
NPAC.

AT THE SURFACE...A LARGE COMPLEX AREA OF LOW PRESSURE PERSISTS
SOUTHWEST OF THE ALEUTIAN CHAIN. A 977 MB IS DEVELOPING ALONG THE
NORTHERN PERIPHERY OF THE JET AND WILL RACE EASTWARD INTO THE GULF
AND MOVE INLAND NEAR JUNEAU SUNDAY AFTERNOON. A 995 MB LOW SOUTH OF
CORDOVA WILL CONTINUE TO WEAKEN AND DISSIPATE OVER THE NEXT 24 HOURS.

.MODEL DISCUSSION...
MODELS INITIALIZE WELL AND ARE IN GREAT AGREEMENT THROUGH 72 HOURS.
DIFFERENCES ARISE TUESDAY NIGHT WHEN THE GFS TRIES TO BRING A 988 MB
LOW INTO THE SOUTHERN BERING SEA. THE MORE LIKELY SOLUTION IS THE
ECMWF WHICH KEEPS THE LOW TRACK SOUTH OF THE CHAIN TOWARD THE AKPEN
THURSDAY NIGHT. WE WILL BE MAKING NO CHANGES TO THE EXTENDED FORECAST
AT THIS POINT...AS THE NIGHT CREW LOADED IN THE 00Z ECMWF. WILL ONLY
BE MAKING MINOR CHANGES TO THE SHORT AND MID TERM FORECASTS.

.SHORT TERM FORECAST...
SOUTHCENTRAL...THE ARCTIC AIRMASS OVER MAINLAND ALASKA CONTINUES TO
BRING BELOW NORMAL TEMPERATURES TO THE AREA. ANCHORAGE SAW ITS
COLDEST TEMPERATURES SINCE FEBRUARY OF 1999. THE SURROUNDING AREA
LOWS RANGED FROM THE SINGLE DIGITS ALONG THE COAST TO -35 INLAND. THE
CHALLENGE CONTINUES TO BE FORECASTING WHEN THIS PATTERN WILL BREAK
DOWN AND MORE NORMAL TEMPERATURES RETURN TO THE AREA. AT THIS
POINT...EXPECTING MORE OF THE SAME THROUGH MIDWEEK. SEVERAL LOWS WILL
DEVELOP ALONG THE JET IN THE NPAC BUT WILL REMAIN WELL SOUTH OF OUR
DOMAIN. THIS WILL KEEP THE COLD AIR OVER MAINLAND ALASKA UNTIL
POSSIBLY THURSDAY WHEN THE MODELS HINT AT A DEVELOPING LOW MAKING ITS
WAY TOWARD THE ALASKA PENINSULA. THIS WOULD BRING A RETURN OF CLOUDS
AND WARMER TEMPERATURES ALOFT...AND SUBSEQUENTLY WARMER TEMPERATURES
AT THE SURFACE. STILL DO NOT SEE ANY GOOD CHANCES OF PRECIPITATION
THROUGH LATE IN THE WEEK.

THE SECOND FORECAST CHALLENGE ARE THE EXTREME WIND CHILLS THROUGH
CHANNELED TERRAIN...FROM THE ALASKA RANGE TO THOMPSON PASS. WIND
CHILL ADVISORIES WILL REMAIN IN EFFECT FOR ZONES 141 145 AND 131
WHERE NORTHERLY WINDS ARE COMBINING WITH THE SUB ZERO TEMPERATURES
RESULTING IN WIND CHILLS READINGS BELOW -40.

SOUTHWEST...COLD DRY AND BREEZY CONDITIONS CONTINUE OVER THE
SOUTHWEST MAINLAND. MCGRATH DROPPED TO -54 BELOW WHILE -20S WERE
PREVALENT ELSEWHERE. WIND CHILL ADVISORIES ARE IN EFFECT FOR 155 AND
161 WHERE WINDS WILL INCREASE THIS EVENING AS THE AFOREMENTIONED 970S
LOW MOVES SOUTH OF THE AKPEN. WILL BE CONSIDERING A WIND CHILL
WARNING FOR 155 WITH THE ISSUANCE OF THE AFTERNOON PACKAGE WHERE -60
WIND CHILLS ARE WITHIN REACH. LIKEWISE FOR THE SOUTHWEST...BEST
CHANCE OF SOME WARMER WEATHER WILL BE MIDWEEK WHEN A NPAC LOW MOVES
NEAR THE AKPEN WHICH COULD SPILL SOME MORE CLIMATOLOGICAL NORMAL
TEMPERATURES ACROSS THE ALASKA RANGE.

.LONG TERM FORECAST...COPIED FROM THE PREVIOUS FORECAST
DISCUSSION....MODELS ARE VERY CONSISTENT IN INDICATING A
CHANGE IN THE LONG-WAVE PATTERN BY THE END OF NEXT WEEK...WITH AN
AMPLIFYING TROUGH BECOMING CENTERED OVER THE BERING/NORTH PACIFIC
AND A RIDGE BUILDING OVER THE EAST PACIFIC/WESTERN NORTH AMERICA.
THIS WILL SET UP A STORM TRACK FROM THE NORTH PACIFIC NORTHWARD TO
THE GULF OF ALASKA. IT IS TOO EARLY TO PINPOINT PARTICULAR
STORMS...BUT EXPECT MODERATING TEMPERATURES ALONG WITH A CHANCE
OF SNOW OVER THE SOUTHERN MAINLAND (ESPECIALLY COASTAL AREAS) BY
THE END OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...121 129 130 155 165 170 172 175 176 179 185.
         HEAVY FREEZING SPRAY WARNING...121 129 130 138 140 141 150
                                        160 165 179 185.
FIRE WEATHER...NONE.

AB JAN 09