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  
 
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