906
FXAK69 PAFG 251219 CCA
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1230 AM AKDT MON OCT 25 2021
SYNOPSIS
A PAIR OF UPPER LOWS ARE MOVING NORTH ACROSS THE MAINLAND, WITH
ONE UPPER TROUGH WRAPPING UP INTO A CLOSED UPPER LOW OVER THE
SEWARD PENINSULA, AND ANOTHER IMPRESSIVE LOOKING OCCLUDED CYCLONE
OVER THE INTERIOR, WHICH IS BRINGING LIGHT SNOW ACCUMULATIONS.
THESE WILL LIFT NORTH AND BRING SNOW TO THE NORTH SLOPE TODAY AND
TONIGHT. LIGHT SNOW SHOWERS WILL CONTINUE OVER THE CENTRAL/EASTERN
INTERIOR INTO THE MIDDLE OF THE WEEK, ALONG WITH FALLING TEMPS.
DISCUSSION
UPPER LEVELS AND ANALYSIS...
THERE IS A 510 DAM 500 HPA TROUGH WRAPPING UP INTO A CLOSED CENTER
OVER THE SEWARD PENINSULA/KOTZEBUE SOUND REGION, WITH ANOTHER
MORE IMPRESSIVE LOOKING OCCLUDED CYCLONE OVER THE INTERIOR TO THE
EAST. THIS RATHER UNUSUAL LOOKING LOW IS BRINGING LIGHT SNOW
SHOWERS TO MUCH OF THE INTERIOR, HEAVIEST ACROSS THE MINTO FLATS
AND NORTH INTO THE UPPER KOYUKUK VALLEY. THE SURFACE LOW OVER THE
WEST COAST IS SITUATED JUST NORTH OF SHISHMAREF AT AROUND 988 MB.
MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN EXCELLENT AGREEMENT THROUGH THE END OF
THE WEEK. THERE ARE MOSTLY SMALL DISCREPANCIES WITH HOW THE
MODELS RESOLVE SUBTLE SHORTWAVE TROUGHS CROSSING THE AK RANGE INTO
THE INTERIOR MIDWEEK, WHICH WILL HAVE AN IMPACT ON WHEN AND WHERE
LIGHT SNOW FALLS. A BLEND WILL BE FAVORED TO DEPICT WIDESPREAD
LIGHT SNOW CHANCES. OUT WEST, THE NAM/GFS WERE FAVORED TO DEPICT
THE TIGHT GRADIENT AND BLUSTERY NW WINDS AT LOW END GALE FORCE.
OVER THE SLOPE, A BLEND WAS FAVORED TO INCREASE SNOW AMOUNTS AND
TO INCREASE NORTHEAST WINDS AS THE LOW CROSSES THE BROOKS RANGE.
CENTRAL AND EASTERN INTERIOR...
LIGHT SNOW WILL GRADUALLY TAPER OFF THIS MORNING AS THE ASSOCIATED
LOW SHIFTS NORTH. ANOTHER 1-2" IS LIKELY OVER THE UPPER KOYUKUK
AND ALONG THE DALTON HIGHWAY NORTH OF LIVENGOOD. EXPECT SOME LOW
STRATUS AND FOG TO REMAIN BEHIND THIS LOW GIVEN THE WEAK GRADIENT.
LIGHT SNOW SHOWERS INCREASE AGAIN ON TUESDAY AS A SERIES OF WEAK
DISTURBANCES CROSS THE AK RANGE AND MOVE INTO THE INTERIOR AND
SHIFT NORTH OVER THE BROOKS RANGE THROUGH WEDNESDAY. EXPECT
WIDESPREAD LIGHT SNOW INTO WEDNESDAY BEFORE TAPERING OFF WEDNESDAY
NIGHT. TEMPS COOL SLIGHTLY AS HIGHS FALL BACK INTO THE LOW 30S AND
THEN THE UPPER 20S.
WEST COAST AND WESTERN INTERIOR...
A DEEPENING LOW OVER THE NW ARCTIC WILL BRING GALE FORCE WINDS TO
THE NORTHERN SEWARD PENINSULA TODAY AND TONIGHT, WITH CONTINUED
SNOW SHOWERS AND SNOW SQUALLS AS THEY WRAP AROUND THE LOW FROM
THE OFFSHORE WATERS. THE LOW MOVES FURTHER NORTH TO WEST OF POINT
HOPE TUESDAY THAT WINDS WILL WANE ALONG THE IMMEDIATE COASTLINES
FOR THE MOST PART, EXCEPT FROM KIVALINA NORTHWEST. PERIODIC LIGHT
SNOW WILL CONTINUE OVER THE COASTAL REGIONS AND AROUND THE
WESTERN BROOKS RANGE, WITH LIGHT SNOW ACCUMULATIONS. EXPECT
PERSISTENT LOW STRATUS AND FOG AT TIMES ACROSS THE YUKON VALLEY.
NORTH SLOPE AND BROOKS RANGE...
LIGHT SNOW WILL INCREASE AS A LOW SHIFTS NORTH OF THE BROOKS RANGE
TODAY, BRINGING A WIDESPREAD SWATH OF 2-3" OF SNOW THROUGH TUESDAY
MORNING BEFORE THE FRONT EXITS OFFSHORE. NORTHEAST WINDS WILL ALSO
INCREASE AND MAY CREATE SOME MINOR AREAS OF BLOWING AND DRIFTING
SNOW, ALTHOUGH THE OVERALL GRADIENT WITH THIS FRONT IS NOT ALL
THAT IMPRESSIVE. EXPECT FOG AND LOW STRATUS TO BE RATHER
WIDESPREAD TUESDAY NIGHT AS THE FRONT EXITS AND THE GRADIENT FALLS
APART. MORE LIGHT SNOW THREATS MOVE IN WEDNESDAY.
EXTENDED FORECAST DAYS 4-7...
TROUGHING WILL ENCOMPASS THE WEST COAST WITH WEAK SOUTH FLOW ALOFT
OVER THE EASTERN INTERIOR ON THURSDAY, BUT WITH THE COLD ARCTIC
HIGH IN PLACE, EXPECT TEMPS TO STILL BE SLOWLY TRENDING DOWNWARD.
THINGS GET VERY VERY INTERESTING FOR THE MAINLAND FOR THE WEEKEND
AS THE TROPICAL REMNANTS OF A STORM SOUTH OF JAPAN GET INGESTED
INTO THE WESTERLY FLOW ALOFT. THIS MAY BE A CLASSIC PATTERN FOR
POTENTIAL HEAVY SNOW FOR PARTS OF THE WEST/CENTRAL INTERIOR WITH
STRONG CHINOOK FLOW ACROSS THE ALASKA RANGE. THE
ECMWF/CANADIAN/GFS ARE ALL ON BOARD WITH THIS OVERALL PATTERN,
WITH A TROUGH OUT WEST AND A STRONG NPAC LOW MOVING TO THE EAST
AND INLAND SOMEWHERE WEST OF THE AK RANGE. STAY TUNED...
COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE.
AFG WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FOR AKZ221.
HEAVY FREEZING SPRAY WARNING FOR PKZ230-PKZ235-PKZ240-PKZ500.
SMALL CRAFT ADVISORY FOR PKZ210.
GALE WARNING FOR PKZ220.
AHSENMACHER OCT 21
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page