672  
FXAK68 PAFC 221252  
AFDAFC  
 
SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ANCHORAGE AK  
452 AM AKDT SAT JUL 22 2017  
   
ANALYSIS AND UPPER LEVELS
 
 
A FAIRLY TRANQUIL PATTERN REMAINS IN PLACE ACROSS THE REGION THIS  
MORNING AS A STOUT RIDGE OVER THE BERING SEA CONTINUES TO EXTEND  
EASTWARD OVER MAINLAND ALASKA. THIS IS YIELDING MOSTLY CLEAR  
SKIES OVER THE SOUTHERN MAINLAND, ALTHOUGH CLOUD COVER IS A  
LITTLE MORE EXTENSIVE ACROSS THE GREATER BRISTOL BAY REGION OWING  
TO WEAK SHOWER ACTIVITY ASSOCIATED WITH A SHORTWAVE THAT PASSED  
THROUGH THE AREA LAST EVENING. WIDESPREAD FOG AND STRATUS REMAIN  
LOCKED IN PLACE ACROSS THE BERING AND ALEUTIANS BENEATH THE  
DOMINANT HIGH PRESSURE.  
 

 
   
MODEL DISCUSSION
 
 
MODELS REMAIN IN STRONG SYNOPTIC AGREEMENT INTO THE BEGINNING OF  
THE WEEK AS THE RIDGE FLATTENS OUT AND GIVES WAY TO ZONAL FLOW  
ACROSS THE BERING SEA AND MAINLAND ALASKA. CONTINUED TO PRIMARILY  
UTILIZE HI-RES NAM GUIDANCE FOR THE MORNING FORECAST PACKAGE TO  
BETTER DEPICT LOCAL INFLUENCES.  
 

 
   
AVIATION
 
 
PANC...VFR CONDITIONS AND LIGHT WINDS WILL PERSIST, WITH LIGHT INLET  
BREEZES ONCE AGAIN DEVELOPING IN THE AFTERNOON.  
 

 
   
SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)
 
 
AN UPPER LEVEL RIDGE CONTINUES TO DRIVE CLEARING AND DRYING  
CONDITIONS ACROSS MUCH OF SOUTHCENTRAL, WITH NOCTILUCENT CLOUDS  
CLEARLY VISIBLE IN THE SKIES EARLY THIS MORNING. THIS RIDGE WILL  
CONTINUE TO SUPPORT MOSTLY CLEAR SKIES AND WARMER TEMPERATURES  
ACROSS SOUTHCENTRAL TODAY AS IT PUSHES FARTHER EASTWARD. SOME  
CLOUDS MAY FORM ALONG THE ALASKA RANGE AND TALKEETNA MOUNTAINS BY  
THE AFTERNOON, BUT CONDITIONS ARE GENERALLY TOO STABLE TO SUPPORT  
ANY SHOWERS.  
 
MORE UNSTABLE WEATHER WILL BEGIN SUNDAY EVENING, AS AN UPPER LEVEL  
WAVE PROGRESSES RAPIDLY FROM THE WEST TO EAST ACROSS SOUTHCENTRAL.  
RAIN IS EXPECTED TO OCCUR MAINLY IN THE NORTHERN SUSITNA VALLEY  
AND NORTHERN COPPER RIVER BASIN. CURRENTLY STEADY RAIN IS NOT  
EXPECTED IN THE ANCHORAGE BOWL OR MATANUSKA VALLEY, BUT THERE  
WILL BE ENOUGH FORCING FOR SOME SCATTERED SHOWERS ALONG THE  
CHUGACH MOUNTAINS SUNDAY NIGHT INTO MONDAY.
 
   
SHORT TERM FORECAST SOUTHWEST ALASKA
 
 
HIGH PRESSURE WILL REMAIN OVER SOUTHWEST ALASKA THROUGH TONIGHT  
BEFORE A FRONT MOVES IN FROM THE NORTHWEST. THE FRONT WILL BRING  
RAIN TO THE REGION BEGINNING WITH THE KUSKOKWIM DELTA AND  
SPREADING EAST THROUGH SUNDAY MAKING IT ACROSS ALL OF SOUTHWEST  
ALASKA SUNDAY NIGHT. ON MONDAY, LIGHTER RAIN WILL PERSIST BEHIND  
THE FRONT AND MAX TEMPS WILL DROP BACK INTO THE 60S FROM THE  
WARMER PREVIOUS COUPLE OF DAYS.  
 

 
   
SHORT TERM FORECAST BERING SEA/ALEUTIANS
 
 
HIGH PRESSURE REMAINS IN PLACE FOR MUCH OF THE BERING AND  
ALEUTIANS KEEPING STRATUS AND FOG WIDESPREAD OVER THESE AREAS.  
HOWEVER, A FRONT HAS BEGUN TO RIDE OVER TOP OF THE RIDGING MOVING  
INTO THE WESTERN BERING. IT WILL PUSH THROUGH THE NORTHERN BERING  
ON SATURDAY AND MAKE IT TO THE WEST COAST BY SUNDAY WITH THE REST  
OF THE FRONT DRAPED ACROSS THE PRIBILOF ISLANDS AND THE SOUTHERN  
BERING. IT WILL THEN SLOWLY TRACK EAST ARRIVING TO THE EASTERN  
ALEUTIANS AND ALASKA PENINSULA ON MONDAY.  
 

 
   
LONG TERM FORECAST (DAYS 3 THROUGH 7)
 
 
THE LONG RANGE FORECAST WILL BE IN A PROGRESSIVE PATTERN AS AN  
UPPER LOW OVER THE ARCTIC SENDS SEVERAL SHORTWAVES TO THE SOUTHERN  
MAINLAND. UNDER THIS REGIME, OCCASIONAL SHOWERS ARE EXPECTED  
MONDAY NIGHT THROUGH FRIDAY ACROSS THE SOUTHERN MAINLAND AND THE  
GULF OF ALASKA. TO THE WEST, A RIDGE TAKES RESIDENCE ALONG THE  
WESTERN HALF OF THE ALEUTIANS KEEPING MUCH OF THE BERING DRY,  
HOWEVER LOW CLOUDS AND FOG WILL PERSIST UNDER THE STABLE AIR MASS.  
THE CENTRAL AND EASTERN BERING WILL MAINLY BE INFLUENCED BY THE  
UPPER LOW. MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH THE  
SYNOPTIC PATTERN THROUGH THE EXTENDED TIMEFRAME, THEREFORE A BLEND  
OF THE OPERATIONAL MODELS AND THEIR ENSEMBLES WERE USED TO UPDATE  
THE LATEST PACKAGE.  
 

 
 
   
AFC WATCHES/WARNINGS/ADVISORIES
 
 
PUBLIC...NONE  
MARINE...NONE  
FIRE WEATHER...NONE  
 

 
 

 
 
SYNOPSIS AND MODEL DISCUSSION...CB  
AVIATION...CB  
SOUTHCENTRAL ALASKA...ELN  
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK  
LONG TERM...KH  
 
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