069
FXAK68 PAFC 020100
AFDAFC
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST SUN MAR 1 2026
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 THROUGH 3/TONIGHT
THROUGH WEDNESDAY)...
A DEEP AND VERY COLD ARCTIC LOW AND TROUGH IS CENTERED OVER THE
CANADIAN ARCTIC AND EXTENDS ACROSS MAINLAND AK AND THE BERING SEA.
IT CONNECTS UP WITH ANOTHER UPPER LEVEL LOW JUST SOUTH OF THE
WESTERN ALEUTIANS. A SERIES OF VERY WEAK SHORT-WAVES ARE EMBEDDED
WITHIN THE NORTHERLY FLOW ACROSS MAINLAND AK, HELPING TO MAINTAIN
THE FRIGID AIRMASS IN PLACE OVER THE STATE. TEMPERATURES ACROSS
SOUTHCENTRAL ARE VERY SIMILAR TO WHAT WAS OBSERVED YESTERDAY,
RISING THROUGH THE SINGLE DIGITS TO TEENS. GAP WINDS ALONG THE
COAST HAVE DIMINISHED A BIT AS THE LOW LEVEL OFFSHORE FLOW HAS
WEAKENED. WITH THE COLDEST AIR SITTING IN THE COPPER BASIN,
SOMEWHAT STRONGER WINDS PERSIST THROUGH THOMPSON PASS INTO VALDEZ
AND THROUGH THE COPPER RIVER DELTA. MEANWHILE, A BROAD TROUGH
PERSIST OVER THE NORTH-CENTRAL PACIFIC, WITH A SHORT-WAVE AND
SURFACE LOW EJECTING OUT OF THE TROUGH AND TRACKING EAST-NORTHEAST
ACROSS THE SOUTHERN GULF. THE BULK OF WIND AND PRECIPITATION IS
OUT OVER THE GULF, THOUGH THERE ARE SOME ELEVATED WINDS AND SNOW
SHOWERS ACROSS KODIAK ISLAND AND THE WESTERN GULF. BASED ON
OBSERVATIONS AND WEBCAMS IN KODIAK CITY, THE SNOW SHOWERS HAVE
BEEN QUITE LIGHT WITH LITTLE OR NO SNOW ACCUMULATION.
PERSISTENCE REMAINS THE KEY WORD FOR THE FORECAST, WITH THE COLD
AND DRY CONDITIONS VERY SLOW TO CHANGE OVER THE NEXT FEW DAYS.
SHORT-WAVES DROPPING OUT OF THE ARCTIC WILL LEAD TO DEVELOPMENT OF
A CLOSED UPPER LOW AND AMPLIFICATION OF THE TROUGH OVER SOUTHWEST
AK AND THE EASTERN BERING SEA. MODEL AGREEMENT WITH TRACK OF THE
UPPER LOW IS QUITE ABYSMAL. HOWEVER, ALL SOLUTIONS ULTIMATELY
ROTATE SHORT-WAVES AROUND THIS NEW LOW CENTER AND ACROSS THE GULF
AND SOUTHCENTRAL, LEADING TO A SHIFT TO SOUTHERLY STEERING FLOW.
THIS COULD BRING A RETURN TO CLOUDS AND SNOW SHOWERS BY WEDNESDAY,
MOST LIKELY FOR THE GULF COAST AND PRINCE WILLIAM SOUND REGIONS.
THIS WILL ALSO ALLOW SOME MODERATION OF TEMPERATURES, WITH A VERY
GRADUAL WARMING TREND OVER THE NEXT FEW DAYS. IN THE MEANTIME,
EXPECT ONE MORE NIGHT SIMILAR TO THE LAST TWO. BASED ON THAT, WILL
RE-ISSUE COLD WEATHER ADVISORIES ONCE AGAIN FOR LOW WIND CHILLS
ALONG THE COAST AND LOW AIR TEMPERATURES IN THE COPPER BASIN. GAP
WINDS WILL PERSIST ALONG THE COAST, WITH SOME FLUCTUATIONS AS WEAK
FEATURES MOVE THROUGH THE NEXT COUPLE DAYS. DEPENDING ON THE
ULTIMATE TRACK OF THE UPPER LOW, THESE WINDS COULD ACTUALLY
LIGHTEN UP ON WEDNESDAY. LASTLY, KODIAK WILL CONTINUE TO SEE A FEW
SNOW SHOWERS THROUGH TOMORROW MORNING, BEFORE CLEARING OUT BY
TOMORROW EVENING.
-SEB
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (DAYS
1 THROUGH 3)...
**KEY MESSAGE: THE COLD WEATHER ADVISORY FOR THE KUSKOKWIM DELTA
HAS BEEN EXTENDED THROUGH 1PM MONDAY FOR WIND CHILLS AS LOW AS 40
BELOW ZERO.
DISCUSSION:
THE MAIN STORY ACROSS THE WESTERN DOMAIN IS THE BITTERLY COLD
TEMPERATURES WITH DANGEROUS WIND CHILLS IN PLACE FOR THE SHORT
TERM. IN FACT, MOST LOCATIONS ARE SITTING AROUND 30 DEGREES BELOW
AVERAGE FOR THIS TIME OF YEAR. A VERY STRONG ~1050 MB ARCTIC HIGH
ANCHORED OVER NORTHEASTERN RUSSIA HAS SUPPRESSED THE STORM TRACK
SOUTH OF THE ALEUTIANS, KEEPING A NORTH PACIFIC LOW NOW SPINNING
SOUTH OF ADAK AND ATKA FROM MAKING ANY FARTHER NORTHWARD PROGRESS.
THAT SAID, THE PRESSURE GRADIENT BETWEEN THE TWO FEATURES IS
QUITE STRONG, KEEPING NORTHEASTERLY WINDS ELEVATED (SUSTAINED 25
KNOTS WITH HIGHER GUSTS) FOR SOUTHWEST ALASKA AND FOR MOST OF THE
BERING SEA, INCLUDING THE PRIBILOF ISLANDS.
ALOFT, A CUT-OFF UPPER LEVEL LOW IS MOVING OVER THE WESTERN
ALEUTIANS, REINFORCING AN UNSEASONABLY COLD AIRMASS AND ALSO
STEEPENING LAPSE RATES AS COLDER AIR WORKS IN ALOFT, AIDING IN
REDEVELOPMENT/ENHANCEMENT OF SNOW SHOWERS. SATELLITE IMAGERY
REVEALS SHALLOW, LOW TOPPED CONVECTION WEST OF THE ICE EDGE (THAT
IS CURRENTLY NOT TOO TERRIBLY FAR FROM THE PRIBILOF ISLANDS)
PRODUCING WIDESPREAD SNOW SHOWERS FOR ESSENTIALLY THE PRIBILOF
ISLANDS AND POINTS WESTWARD AS COLD AIR ADVECTION STREAMS OFF OF
THE SEA ICE AND OVER RELATIVELY WARMER WATER, LEADING TO LOW LEVEL
INSTABILITY. EXPECT THIS TYPE OF SETUP TO HOLD FOR THE REST OF
THE SHORT TERM.
AS NOTED IN THE KEY MESSAGE, THE COLD WEATHER ADVISORY HAS BEEN
EXTENDED THROUGH 1PM TOMORROW AFTERNOON FOR THE KUSKOKWIM DELTA AS
THE ARCTIC AIRMASS EVER SO SLIGHTLY MODERATES, BUT STILL REMAINS
CLOSE ENOUGH TO WHERE IF OVERNIGHT LOW TEMPERATURES EVEN SLIGHTLY
OVERPERFORM, WIND CHILLS FOR THE KUSKOKWIM DELTA WILL ONCE AGAIN
DROP INTO THE -40S AND HIT CRITERIA. MEANWHILE, THE UPPER LEVEL
LOW NOW OVER SHEMYA DIVES SOUTHWARD OVER THE NORTH PACIFIC BY
MONDAY MORNING, WHICH WILL CAUSE A DECREASE IN SNOW SHOWER
COVERAGE AND PERHAPS SOME VERY MODEST WARMING AS WE LOSE THE
COLDER AIR ALOFT ASSOCIATED WITH THE FEATURE. FOR SOUTHWEST
ALASKA, IT WILL BE A VERY SLOW ATTEMPT TO CRAWL OUT OF THE DEEP
FREEZE THROUGH MOST OF THE SHORT TERM...UNTIL A REINFORCING PUSH
OF ARCTIC AIR ARRIVES TUESDAY AS SHORTWAVE ENERGY DRIVES INTO THE
REGION.
LOOKING AHEAD TO WEDNESDAY, THIS FRIGID PATTERN POTENTIALLY SHOWS
THE FIRST SIGNS OF BREAKING AS THE AFOREMENTIONED ARCTIC HIGH
WEAKENS AND RETREATS FARTHER NORTH AND LOSES ITS INFLUENCE ACROSS
THE REGION. WINDS SHOULD BECOME LIGHTER AS WELL AS THE PRESSURE
GRADIENT STARTING TO RELAX A BIT. THE GLOBAL MODELS WEDNESDAY
MORNING SHOWS SOME INDICATION OF THE NORTH PACIFIC STORM TRACK
VENTURING BACK NORTHWARD, WHICH IN TURN WILL START TO BRING
PRECIPITATION CLOSER TO THE ALEUTIAN CHAIN FROM THE SOUTH. AROUND
THIS TIME, 500 MB ANALYSIS SHOWS A TROUGH DIGGING SOUTHWARD OVER
THE WESTERN BERING AND CLOSING OFF INTO AN UPPER LEVEL LOW THAT
DRIVES SOUTHWARD TOWARDS THE WESTERN ALEUTIANS.
-AM
.LONG TERM FORECAST (DAYS 4 THROUGH 7 - THURSDAY THROUGH
SUNDAY)...
UPPER-LEVEL TROUGHING CENTERED OVER THE STATE MID TO LATE THIS
WEEK WILL EXTEND SOUTH INTO THE NORTHERN PACIFIC, WITH MULTIPLE
SHORTWAVES ROTATING AROUND THE TROUGH. SOME MODEL DIFFERENCES IN
THE POSITION AND TRACK OF RESULTING SURFACE LOWS LIFTING INTO THE
GULF WILL CONTINUE TO KEEP THE PRECIPITATION FORECAST CONFIDENCE
BELOW AVERAGE FOR THE LONG TERM. A LEAN TOWARDS THE GFS ENSEMBLES
BRINGS A SHORTWAVE OVER THE WESTERN ALEUTIANS BY MID TO LATE WEEK
WITH A SHOT OF COLDER TEMPERATURES DROPPING SOUTHWARD OUT OF
NORTHEAST RUSSIA AND INTO THE WESTERN BERING. A NORTH PACIFIC LOW
LIFTS INTO THE GULF BY FRIDAY MORNING, BRINGING INCREASED SNOW
CHANCES ACROSS THE NORTHERN GULF COAST AND PRINCE WILLIAM SOUND
WITH THE POTENTIAL FOR SNOW SHOWERS TO OVERSPREAD INLAND LOCATIONS
OF SOUTHCENTRAL THROUGH SATURDAY. ADDITIONALLY, STRONG
NORTHWESTERLY FLOW AND COLD AIR ADVECTION BEHIND THE GULF LOW WILL
LEAD TO THE POTENTIAL FOR STRONG GAP WINDS ACROSS THE BARREN
ISLANDS AND SOUTHERN ALASKA PENINSULA. WHILE FORECAST CONFIDENCE
IS LOW WITH REGARD TO WHERE SURFACE FEATURES AND PRECIPITATION
ULTIMATELY DEVELOP, FORECAST CONFIDENCE IS HIGH THAT BOTH
SOUTHWEST AND SOUTHCENTRAL ALASKA WILL CONTINUE TO SEE BELOW
NORMAL TEMPERATURES THROUGH THE END OF THIS WEEK.
AVIATION
PANC...VFR CONDITIONS AND LIGHT NORTHERLY WINDS WILL PERSIST.
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