Area Forecast Discussion - Southeastern
FXAK67 PAJK 270037
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
337 PM AKST MON JAN 26 2015
.SHORT TERM...ARCTIC FRONT IS CURRENTLY DRAPED ACROSS THE NORTHERN
FRINGE. MODELS DON'T HAVE MUCH SOUTHWARD PROGRESS OVER THE NEXT
24-30 HOURS THOUGH...BUT IT WILL BE MUCH COOLER OVER THE NEXT 24
HOURS AREA-WIDE COMPARED TO RECENT TEMPS. MEANWHILE WE HAVE MOSTLY
CLOUDY SKIES OVER THEN NORTHERN PANHANDLE WITH PARTLY CLOUDY OVER
PARTS OF THE CENTRAL & SOUTH. A FEW RESIDUAL, TEMPORARY SHOWERS
EXIST OVER THE NORTH. NO WIND ISSUES AT THE MOMENT...BUT EXPECT
STRENGTHENING WINDS IN NORTHERN LYNN CANAL SHORTLY. WEAK LOW
SPINNING SOUTH OF KETCHIKAN SHOULD GRADUALLY WEAKEN AND MOVE EAST
AND WILL AFFECT ONLY THE FAR SOUTH END WITH SOME LIGHT RAIN OVER
THE NEXT 24 HOURS OR SO. MEANWHILE A NEW LOW ENTERS THE GULF FROM
THE SOUTHWEST THIS EVENING AND GRADUALLY BECOMES ESTABLISHED AND
MOVES NORTHEASTWARD ON TUES...WITH WINDS REACHING SCA-LEVEL OVER
ZONE 310 BY 03Z WED BUT STILL IN THE 15-20 KT RANGE FOR EVEN THE
SOUTHERNMOST CHANNELS AT THIS TIME AND SOUTHEASTERLIES JUST
BEGINNING TO PICK UP ON THE CENTRAL/NORTHERN COAST. MEANWHILE FLOW
AROUND THE ANTICYCLONE TO THE NORTH WILL AFFECT PRIMARILY THE
NORTHERN FRINGE OVER THE NEXT 24-30 HOURS WITH SOME NORTHEASTERLY
WINDS AND A BIT DRIER CONDITIONS. NORTHERN LYNN SHOULD GET TO SCA-
LEVEL WINDS IN THE NEXT FEW HOURS ONCE IT SWITCHES TO A NORTH
DIRECTION. FOG FORMATION IS LIKELY OVER FAVORED AREAS IN THE
PANHANDLE TONIGHT WITH BREAKS IN THE CLOUDS AND SUBSTANTIAL
COOLING...KEPT IT IN THE PATCHY CATEGORY. BREAKS IN CLOUDS WILL
PERSIST ABOVE ANY FOG INTO TUES AM...BUT WILL LIKELY SEE A HIGH
OVERCAST INCREASE FROM THE SOUTHWEST ON TUES IN ADVANCE OF THE NEW
SYSTEM. MODELS HAVE BEEN CONSISTENT ON THESE FEATURES LARGELY OVER
THE LAST COUPLE OF DAYS. DYNAMIC FIELDS DID NOT REQUIRE ANY
TWEAKS IN THE GRIDS OTHER THAN TO PLAY WITH CHANNEL WINDS A
BIT...OVER CROSS SOUND, YAKUTAT VICINITY AND FREDERICK SOUND FOR
SLIGHT SPEED INCREASES. UPDATED THE THERMODYNAMIC FIELDS WITH AN
EC/NAM/INHERITED COMBO...ENDED UP MINOR. BIGGEST QUESTION IS HOW
MUCH/DEEP COLD AIR WILL BE IN PLACE OVER THE NORTHERN FRINGE WHEN
THIS NEW SYSTEM ARRIVES WITH PRECIP BEGINNING LATE TUESDAY
EVENING...PRECIP TYPE WILL LIKELY BE AN ISSUE INTO AT LEAST
WEDNESDAY FOR THE NORTHERN HALF OR SO AS RAIN/SNOW LINE WORKS ITS
WAY NORTHWARD. NEW GUIDANCE DATA REQUIRED NO MAJOR CHANGES TODAY.
.LONG TERM...THE NEXT GALE FORCE FRONT WILL APPROACH SOUTHEAST
ALASKA FROM THE SOUTHWEST ON TUESDAY NIGHT. SOMEWHAT COLDER AIR IN
PLACE AT THE START OF THIS EVENT WILL RESULT IN A LITTLE SNOW
TUESDAY NIGHT THROUGH WEDNESDAY. LOOK FOR UP TO 3 TO 4 INCHES OVER
SOME INNER CHANNEL LOCATION SUCH AS JUNEAU...BEFORE IT TURNS BACK
TO RAIN. REASON FOR THAT WILL BE A MODEST AMOUNT OF LOW LEVEL WARM
AIR ADVECTION THAT WILL MOVE NORTH BEHIND THE FRONT AND PUSH THE
ARCTIC FRONT NORTH INTO THE YUKON ONCE MORE. PRECIP WILL LINGER
OVER THE PANHANDLE THROUGH THURSDAY NIGHT, RESULTING IN MOSTLY
RAIN BY DAY AND A MIX OF RAIN AND SNOW AT NIGHT. NEXT SIGNIFICANT
FRONT WILL ARRIVE ON SATURDAY, WITH FAIRLY STRONG WARM AIR
ADVECTION BEHIND THE FRONT. OPPOSING THIS WILL BE ANOTHER
SOUTHERLY SURGE OF THE ARCTIC FRONT. IN BETWEEN, THE PRESSURE
GRADIENT WILL INCREASE DRAMATICALLY AND RESULT IN FALLING
TEMPERATURES THROUGH THE WEEKEND INTO NEXT WEEK AS WELL AS SOME
VERY WINDY CONDITIONS THIS WEEKEND IN THE USUAL OUTFLOW LOCATIONS
OVER LAND AS WELL AS THE INNER CHANNELS. STRONG WIND HEADLINES
WILL ALMOST CERTAINLY BE NECESSARY. HIGH WIND WARNINGS A
POSSIBILITY, SO STAY TUNED.

USED A BLEND OF GFS AND ECMWF THROUGH THURSDAY NIGHT. ECMWF ON
FRIDAY, THEN AN ECMWF/WPC BLEND TO THE END. POP AND QPF PRIMARILY
FROM GFS WITH SOME HELP FROM ECMWF. TEMPERATURE ADJUSTMENTS FROM
BIAS CORRECTED MOS. OVERALL FORECAST CONFIDENCE IS AVERAGE. 

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-041. 
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ042. 

&&

$$

WESLEY/FRITSCH

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