836
FXAK68 PAFC 191432
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
532 AM AKST TUE NOV 19 2024
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3/TODAY
THROUGH THURSDAY NIGHT)...
KEY MESSAGES:
* WINDS HAVE PEAKED ACROSS MOST OF SOUTHCENTRAL AND WILL STEADILY
DIMINISHING TODAY THROUGH TONIGHT, BECOMING LIGHT INLAND. GAP
WINDS WILL LINGER ALONG THE COAST THROUGH MUCH OF THE WEEK.
* STRONG AND GUTSY WINDS WILL LINGER IN THE MATANUSKA VALLEY AND
VALDEZ/THOMPSON PASS AREAS THIS MORNING, LEADING TO BLOWING AND
DRIFTING SNOW ALONG ROADWAYS. STRONGER GUSTS COULD LOFT SNOW
AND LEAD TO REDUCED VISIBILITY AT TIMES.
* THE COLDEST TEMPERATURES WILL BE TODAY THROUGH WEDNESDAY
MORNING, WITH WARMING TEMPERATURES FOR THE LATTER HALF OF THE
WEEK. DRY CONDITIONS WILL PERSIST THROUGH THE END OF THE WEEK
AND PERHAPS BEYOND.
A STRONG HIGH AMPLITUDE RIDGE OVER THE BERING SEA IS BUILDING
EASTWARD TOWARD MAINLAND ALASKA THIS MORNING. A 150KT+ JET STREAK
HAS DEVELOPED ON THE LEADING EDGE OF THE RIDGE, RIDING FROM NORTH
TO SOUTH ACROSS WESTERN AK AND SLOWLY SHIFTING EASTWARD INTO
SOUTHCENTRAL. STRONG SUBSIDENCE AND AN ASSOCIATED TROPOPAUSE FOLD
ON THE POLEWARD SIDE (EAST SIDE) OF THE JET WILL BRING ONE LAST
SURGE IN WINDS THIS MORNING, MOST NOTABLY FOR THE MATANUSKA VALLEY
AND VALDEZ/THOMPSON PASS AREAS. WEB CAMS SHOW AREAS OF BLOWING
AND DRIFTING SNOW ALONG SOME ROADWAYS, INCLUDING THE GLENN HIGHWAY
IN PALMER, ALONG WITH OCCASIONAL BRIEF REDUCTIONS IN VISIBILITY
AS STRONGER GUSTS LOFT SNOW INTO THE AIR. A HIGH WIND WARNING (75
MPH) FOR THOMPSON PASS HAS BEEN EXTENDED THROUGH 11AM TO ACCOUNT
FOR THIS LAST SURGE IN WINDS. STRONG GUSTY GAP WINDS REMAIN
FAIRLY STEADY ALONG THE COAST, INCLUDING FOR KODIAK ISLAND. GUSTY
WINDS, THOUGH QUITE A BIT LIGHTER, CAN BE FOUND ACROSS MUCH OF
INLAND SOUTHCENTRAL THIS MORNING. TEMPERATURES VARY SIGNIFICANTLY
BETWEEN WINDY PLACES AND PLACES WITH LIGHT OR CALM WINDS. FOR
EXAMPLE, THE HOUSTON TO WILLOW AREA IS SITTING AT AROUND 15 TO 20
BELOW ZERO WHILE TEMPERATURES ARE IN THE TEENS (ABOVE ZERO) JUST
TO THE EAST IN WASILLA AND PALMER WHERE THE WINDS ARE BLOWING
QUITE STRONGLY. CLEAR SKIES PREVAIL FOR NEARLY ALL OF SOUTHCENTRAL
WITH A VERY DRY AIR MASS IN PLACE. THE 12Z ANCHORAGE SOUNDING
RECORDED A TOTAL PRECIPITABLE WATER VALUE OF ONLY 0.06"!
WINDS WILL STEADILY DIMINISH THIS THROUGH THE DAY, BECOMING CALM
FOR MOST INLAND LOCATIONS BY THIS EVENING. WITH A COLD AND DRY
AIRMASS IN PLACE AND LIMITED DAYLIGHT HOURS, TEMPERATURES WILL
LIKELY HOLD STEADY OR FALL AS THE WINDS DIMINISH. WHERE
TEMPERATURES DO RISE WITH AFTERNOON SUNSHINE, IT WILL BE BRIEF.
TONIGHT WILL LIKELY BE THE COLDEST NIGHT OF THE WEEK FOR A LOT OF
LOCATIONS DESPITE SOME PASSING CIRRUS CLOUDS AND WARMING UPPER
LEVEL TEMPERATURES AS THE RIDGE BUILDS IN. THE VERY STRONG SINKING
AIR ON THE LEADING EDGE OF THE RIDGE AND RESULTANT DRY AIRMASS
WILL LEAD TO EFFECTIVE RADIATIONAL COOLING AT THE SURFACE. THUS,
HAVE TRENDED COLDER WITH THE TEMPERATURE FORECAST FOR TONIGHT INTO
WEDNESDAY MORNING. TEMPERATURES WILL THEN BEGIN TO STEADILY WARM
EACH DAY FOR THE REMAINDER OF THE WEEK UNDER THE INFLUENCE OF THE
STRONG BLOCKING RIDGE, WHICH WILL REMAIN CENTERED JUST UPSTREAM
OVER BRISTOL BAY AND THE ALASKA PENINSULA. FOR WESTERN PORTIONS
OF SOUTHCENTRAL, INCLUDING THE KENAI PENINSULA AND ANCHORAGE
AREAS, TEMPERATURES WILL WARM THE MOST AT ELEVATION, RISING ABOVE
FREEZING BETWEEN AROUND 1500 FEET AND 8000 FEET ELEVATIONS
THURSDAY THROUGH FRIDAY. DESPITE STRONG TEMPERATURE INVERSIONS,
FOG IS UNLIKELY IN SUCH A DRY AIRMASS. MEANWHILE, PERSISTENT
NORTHERLY (OFFSHORE) FLOW EAST OF THE UPPER RIDGE CENTER COMBINED
WITH THERMAL AND PRESSURE GRADIENTS BETWEEN INLAND AREAS AND THE
COAST WILL MAINTAIN GAP WINDS ALONG THE COAST ALONG WITH SOMEWHAT
WARMER TEMPERATURES.
-SEB
.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING
SEA/ALEUTIANS (DAYS 1 THROUGH 3)...
A TROUGH WILL CONTINUE TO BRING GUSTY CONDITION TO THE ALASKA
PENINSULA THROUGH THIS AFTERNOON. A RIDGE OF HIGH PRESSURE MOVES
IN BEHIND IT AND WILL INFLUENCE THE WEATHER PATTERN IN SOUTHWEST
ALASKA, THE BERING SEA AND THE ALEUTIANS THROUGH THE END OF THIS
WEEK.
THE TROUGH MOVING THROUGH SOUTHWEST ALASKA BRINGING STRONG
NORTHERLY WINDS THROUGH THE ALASKA PENINSULA AND EASTERN
ALEUTIANS WILL DISSIPATE TODAY. SURFACE OBSERVATIONS FROM THE
PAST TWELVE HOURS ENDING AT 4:00 AM THIS MORNING SHOWED WIDESPREAD
WIND GUSTS IN THE 55 TO 65 MPH RANGE FROM THE PASSES AND BAYS
FROM COLD BAY TO PORT HEIDEN. WIND GUSTS WILL RANGE FROM 45 TO 55
MPH THROUGH THE AFTERNOON HOURS BEFORE THE WIND SHIFTS TO A MORE
NORTHEASTERLY DIRECTION AND CAUSING THE WINDS TO QUICKLY DECREASE.
A RIDGE OF HIGH PRESSURE CONTINUES TO BUILD OVER THE ALEUTIANS AND
SOUTHWEST ALASKA TODAY. IT WILL REMAIN IN PLACE THROUGH THE
END OF THE WEEK ALLOWING FOR WARM AIR TO QUICKLY MOVE INTO THE
REGION. HIGH TEMPERATURES ARE EXPECTED TO WARM 15 TO 20 DEGREES
FROM TODAY TO THURSDAY ACROSS SOUTHWEST ALASKA. TEMPERATURES
ACROSS SOUTHWEST ALASKA AS OF 4:00 AM RANGE FROM 25 TO 15 DEGREES
BELOW ZERO WITH LOCATIONS ALONG THE COAST A FEW DEGREES BELOW 10.
INCREASED CLOUD COVER THIS MORNING OVER PORTIONS OF INTERIOR SOUTHWEST
ALASKA IS HELPING TO BRING THE OVERNIGHT LOWS UP QUICKLY. FOR
EXAMPLE, ANIAK ROSE FROM -17 AT 1:45 AM TO -6 AT 4:15 AM AS
CLOUDS BUILT IN OVERHEAD.
A WAVE OF PRECIPITATION WILL MOVE OVER THE PRIBILOF ISLANDS
NORTHEASTWARD TO KIPNUK TODAY. QPF AMOUNTS WILL BE LIGHT WITH ONLY
FLURRIES EXPECTED BECAUSE MOST OF THE PRECIPITATION WILL MOVE
AROUND THE RIDGE OF HIGH PRESSURE TO AREAS NORTH OF NEWTOK. WARM
AIR OVER THE REGION WILL RESULT IN WIDESPREAD AREAS OF FOG BY MID-
WEEK.
TOWARD THE END OF THE WEEK, THE HIGH PRESSURE WILL SHIFT EAST
ALLOWING FOR A QUICK MOVING LOW FROM THE NORTH PACIFIC TO TRAVEL
THROUGH THE ALEUTIANS WEST OF ADAK BRINGING GUSTY WINDS AND RAIN
SHOWERS FROM THERE TO SHEMYA.
-DJ
LONG TERM FORECAST (DAYS 4 THROUGH 7: FRIDAY THROUGH MONDAY)
ON THE ALASKA WEATHER MAP, HIGH PRESSURE MUSCLES ITS WAY ACROSS
THE SOUTHERN HALF OF THE STATE THROUGH THE FORECAST PERIOD. THIS
RIDGE BRINGS LIGHT WINDS, DRY CONDITIONS AND MORE MODERATE
TEMPERATURES IN THE ZONAL FLOW ACROSS MOST OF THE STATE THROUGH
THE WEEKEND, ALTHOUGH COOLEST OVERALL TEMPERATURES SHOULD LINGER
OVER THE EASTERN INTERIOR THROUGH MONDAY. PRECIPITATION, IF ANY,
WILL BE LIGHT AND INTERMITTENT THROUGH THE WEEKEND.
THE MOST ACTIVE WEATHER IS EXPECTED ACROSS THE WESTERN ALEUTIANS
AND BERING, AS A NUMBER OF LOW AND TROUGHS RIDE UP OVER THE
WESTERN FLANK OF THE RIDGE. THESE WEAK SYSTEMS BRING AREAS OF
OCCASIONALLY MODERATE RAINFALL AND SOME GUSTY WINDS. FORECAST
MODELS INDICATE WEAK WAVES THROUGH THE WEEKEND, BUT STEPPING UP BY
THE NEW WEEK WITH MORE DEVELOPED LOWS WORKING INTO THE PATTERN
FROM THE NORTH PACIFIC SUNDAY INTO MONDAY. THESE STRONGER LOWS
BRING LOCALLY HEAVY RAINS AND GUSTIER WINDS UP TO GALE FORCE OVER
THE WESTERN ALEUTIANS AND BERING, DRIFTING INTO THE CENTRAL
ALEUTIANS AND BERING FOR MONDAY.
.AVIATION...
PANC...VFR CONDITIONS WILL PERSIST. NORTHERLY WINDS HAVE PEAKED
AND SILL DIMINISH THROUGH THE DAY AS HIGH PRESSURE BUILDS IN
FROM THE WEST.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page