315
FXAK68 PAFC 201411
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
511 AM AKST THU FEB 20 2025
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3)
DISCUSSION:
AN ELONGATED TROUGH STRETCHING WEST-TO-EAST THIS MORNING WILL
CONTINUE TO LIFT NORTHWARDS TODAY. THE EASTERN END OF THIS LOW WILL
SEPARATE BEFORE DEEPENING OVER THE CENTRAL GULF LATER THIS
AFTERNOON. ITS FRONT WILL SWEEP ACROSS THE NORTHERN GULF BRINGING
ADDITIONAL PRECIPITATION TO THE COASTAL AREAS OF THE NORTHERN GULF,
PRINCE WILLIAM SOUND, AND EASTERN KENAI. ONCE AGAIN, IT LOOKS LIKE
THE LOWER ELEVATIONS SHOULD REMAIN MOSTLY RAIN WITH ELEVATIONS ABOVE
500-1000 FEET SEEING A CHANGEOVER TO SNOW. MODELS ARE IN GOOD
AGREEMENT WITH TRACKING THIS LOW WESTWARD OVER THE KENAI PENINSULA
BY FRIDAY MORNING. IN RESPONSE, WINDS WILL INCREASE OVER THE KENAI
AND WESTERN CHUGACH MOUNTAINS TONIGHT THROUGH FRIDAY AFTERNOON.
WHILE THE BULK OF THE PRECIPITATION WILL REMAIN ON THE GULF SIDE,
WILL LIKELY SEE SOME PRECIPITATION MAKE IT INTO THE COPPER BASIN.
PRECIPITATION CHANCES WILL ALSO INCREASE OVER THE NORTHERN SUSITNA
VALLEY ALONG THE ALASKA RANGE AS UPSLOPE INCREASES WITH THE
APPROACHING SYSTEM. WHAT'S LEFT OF THE WESTERN HALF OF TODAY'S
ELONGATED LOW WILL BE SWEPT UP WITH A SHORTWAVE TROUGH LIFTING
NORTH OUT OF THE PACIFIC LATE FRIDAY INTO SATURDAY, REINFORCING LIFT
AND CONTINUED UNSETTLED WEATHER FOR THE GULF.
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3: TODAY THROUGH SATURDAY NIGHT)...
BROAD LOW PRESSURE IN THE BERING SEA WILL BRING A CHANCE OF SNOW
SHOWERS TO THE WESTERN ALEUTIANS FOR THE LATTER HALF OF THE WEEK
AND INTO THE WEEKEND. A SURFACE LOW MOVING WEST OF THE PRIBILOF
ISLANDS HAS ALREADY BEGUN WRAPPING IN A COLDER AIR MASS,
SIGNIFICANTLY DROPPING TEMPERATURES OVER THE WESTERN BERING. WEAK
UPPER LEVEL FEATURES WILL PROVIDE SUPPORT TO LOCALLY ENHANCE
SHOWERS AS THEY MOVE THROUGH THE FLOW.
SOUTHWEST ALASKA WILL CONTINUE TO SEE AN ACTIVE WEATHER PATTERN
CHARACTERIZED BY SHOWERY PRECIPITATION AND EASTERLY TO
NORTHEASTERLY FLOW AS ANOTHER NORTH PACIFIC LOW STALLS AND WEAKENS
SOUTH OF THE ALASKA PENINSULA THROUGH FRIDAY. IN ITS WEAKENED
STATE, THE LOW LIMPS INTO BRISTOL BAY ON SATURDAY, AND ALTHOUGH
THE MAJORITY OF PRECIPITATION WILL BE ON THE PACIFIC SIDE OF THE
ALASKA PENINSULA, THE POTENTIAL FOR LIGHT PRECIPITATION PERSISTS
ALONG THE COASTAL MAINLAND. THE HEIGHT OF THE FREEZING LAYER
SHOULD CONTINUE TO LOWER, CHANGING PRECIPITATION TYPE AROUND
BRISTOL BAY AND THE ALASKA PENINSULA FROM RAIN AND RAIN/SNOW MIX
TO ALL SNOW BY SATURDAY. SURFACE TEMPERATURES ACROSS MOST OF
WESTERN ALASKA WILL HOVER IN THE MID TO LOW THIRTIES, WITH THE
EXCEPTION BEING FARTHER NORTH ACROSS THE KUSKOKWIM DELTA WHERE
TEMPERATURES IN THE TEENS AND TWENTIES ARE FORECAST.
LONG TERM FORECAST (DAYS 4 THROUGH 7) SUNDAY THROUGH WEDNESDAY
LITTLE CHANGE IS EXPECTED IN THE LARGE SCALE UPPER LEVEL PATTERN
MOVING INTO THE LONG TERM. BROAD UPPER LEVEL TROUGHING IS EXPECTED
TO CONTINUE ACROSS THE BERING SEA AND ALEUTIANS. THE GULF OF
ALASKA WILL ALSO GENERALLY EXPERIENCE LOW PRESSURE AS THE UPPER
LEVEL RIDGE REMAINS SETTLED ACROSS MUCH OF THE ALASKAN MAINLAND
AND ITS RIDGE AXIS STRETCHING ACROSS THE ALASKA-CANADA BORDER.
THERE IS MODERATE FORECAST CONFIDENCE WITH THE LONG TERM. EQUAL
WEIGHT WAS GIVEN BETWEEN ALL OF THE GLOBAL MODELS AS THEY ARE IN
RELATIVE AGREEMENT WITH THE LARGER FEATURES. HOWEVER, THERE IS
SOME UNCERTAINTY ABOUT TIMING AND INTENSITY OF THE UPPER LEVEL
SHORTWAVES AND ASSOCIATED WEAK SURFACE LOWS.
THIS PATTERN WILL ALLOW FOR SHORTWAVE TROUGHS AND ASSOCIATED
SURFACE FRONTS TO QUICKLY MOVE IN SUCCESSION ACROSS THE ALEUTIAN
ISLANDS AND COASTAL SOUTHCENTRAL REGIONS. EXPECT PRECIPITATION
AND UNSEASONABLE WARMER TEMPERATURES TO PERSIST FOR THE ALASKA
PENINSULA AND GULF THROUGH THE LONG TERM. THERE IS A POTENTIAL FOR
HEAVY SNOW ACCUMULATIONS IN THE HIGHER COASTAL ELEVATIONS WITH
EACH SUCCESSIVE SYSTEM.
-DD/RUX
AVIATION
PANC...VFR CONDITIONS AND LIGHT NORTHERLY WINDS WILL PERSIST. A FEW
WEAK EASTERLY WAVES WILL MOVE ACROSS THE TERMINAL TODAY, WITH A
FRONT MOVING INTO SOUTHCENTRAL BY FRIDAY, BUT PRECIPITATION AND
SIGNIFICANTLY LOWER CEILINGS LOOK UNLIKELY WITH ANY OF THESE
FEATURES.
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