FXAK69 PAFG 232246
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
146 PM AKST WED DEC 23 2009
DISCUSSION...
A LESS ACTIVE WEATHER PATTERN THAN THE LAST SEVERAL DAYS. AN
UPPER LOW ACROSS THE CENTRAL AND WESTERN BERING SEA WILL CONTINUE
TO SLOWLY RETROGRADE TO THE WEST AND WILL BE CENTERED ACROSS
KAMCHATKA BY THURSDAY EVENING. AN UPPER LEVEL RIDGE TO THE NORTH
OF THE STATE WILL REMAIN IN PLACE THROUGH THE END OF THE WEEK. AN
UPPER LOW ACROSS THE NORTHERN CANADIAN ARCHIPELAGO WILL SLIDE
SOUTHWEST TO BANKS ISLAND ON FRIDAY.
AT THE SURFACE...A STRONG SURFACE HIGH NEAR THE POLE WILL GRADUALLY
DROP SOUTH AND WILL BE CENTERED NEAR 80N 150W BY 00Z SATURDAY. A
982 MB LOW IN THE NORTHERN GULF EARLY THIS MORNING WILL WEAKEN
TODAY AND MOVE INTO COOK INLET. THE LOW WILL CONTINUE TO WEAKEN INTO
A SURFACE TROUGH THAT WILL EXTEND FROM THE NOATAK VALLEY SOUTH TO
THE NORTON SOUND BY LATE TONIGHT. A 960 MB NEAR 45N 165W THIS
MORNING WILL SLOWLY WEAKEN AND DRIFT NORTHEAST TO AROUND 50N 155W
BY FRIDAY MORNING.
NORTH SLOPE...A SURFACE TROUGH ALONG THE COASTAL PLAIN WILL
GRADUALLY SINK SOUTH AND WEAKEN THROUGH THURSDAY AS THE STRONG RIDGE
NEAR THE POLE BEGINS TO BUILD SOUTH. THE PRESSURE GRADIENT WILL
SLOWLY TIGHTEN UP ALONG THE COAST...AND BRISK WIND ADVISORIES HAVE
BEEN ADDED FOR THE NORTH SLOPE MARINE ZONES. THE BRISK WINDS WILL
LIKELY CONTINUE FOR SEVERAL DAYS AS A MODERATE PRESSURE GRADIENT
REMAINS IN TACT INTO THE WEEKEND. THIS IS SOMETHING THAT WILL NEED
TO BE WATCHED FOR THE POTENTIAL OF BLOWING SNOW BY LATE THURSDAY
INTO SATURDAY.
WEST COAST...THERE MAYBE SOME AREAS OF SN-/SW- IN THE VICINITY OF
THE SURFACE TROUGH LATER TONIGHT AND THURSDAY...BUT AMOUNTS LOOK
LIGHT. AS THE STRONG SURFACE HIGH BUILDS SOUTH OUT OF THE HIGH
ARCTIC AND LOW PRESSURE LIFTS TOWARD THE WESTERN GULF OF ALASKA
FRIDAY INTO FRIDAY NIGHT THE PRESSURE GRADIENT WILL BEGIN TO
TIGHTEN UP AND WILL LIKELY LEAD TO BRISK WINDS ACROSS THE COASTAL
WATERS.
INTERIOR...THE CHINOOK FLOW INCREASES FOR A TIME LATER TODAY AHEAD
OF THE UPPER TROUGH THAT IS ASSOCIATED WITH THE SURFACE LOW IN THE
NORTHERN GULF. THE UPPER TROUGH LIFTS NORTH OF THE AK RANGE THIS
EVENING WHICH WILL ALLOW THE FLOW TO WEAKEN. THERE IS SOME SUPPORT
ALOFT FOR SOME STRONGER WIND...BUT AT THIS POINT IT LOOKS LIKE THE
WIND WILL REMAIN JUST BELOW ADVISORY LEVELS.
MID-RANGE...THE OPERATIONAL MODELS ARE IN BETTER AGREEMENT THIS
MORNING. AN UPPER LOW ACROSS THE NORTHERN CANADIAN ARCHIPELAGO
DROPS DOWN TO BANKS ISLAND ON FRIDAY...AND THEN THE LOW BEGINS TO
SPLIT AROUND A STRONG HIGH THAT REMAINS CENTERED ACROSS THE ARCTIC
WATERS NORTH OF THE STATE THROUGH THE WEEKEND. ONE PIECE OF THE
LOW EJECTS OFF ACROSS CANADA TOWARD HUDSON BAY. ANOTHER PIECE OF
THE LOW SLIDES OFF TO THE SOUTHWEST ACROSS NORTHERN AK AND ENDS UP
IN THE VCNTY OF THE BERING STRAIT BY THE END OF THE WEEKEND. THIS
WILL ALLOW A COLDER AIR MASS TO TEMPORARILY OVERSPREAD NORTHERN AK
THIS WEEKEND. EVENTUALLY BY EARLY NEXT WEEK IT LOOKS LIKE THE
CHINOOK FLOW MAY ONCE AGAIN RETURN AS THE LOW DRIFTS WEST OF THE
STATE AND RIDGING DEVELOPS ACROSS WESTERN CANADA IN THE WAKE OF
THE LOW THAT MOVES OFF TOWARD HUDSON BAY.
COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
BRISK WIND ADVISORY FOR PKZ230...235...240...245.
&&
$$
JK DEC 09
