FXAK69 PAFG 251312
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
412 AM AKST FRI DEC 25 2009
.DISCUSSION...
A STRONG UPPER HIGH CENTERED ABOUT 400 MILES NORTH OF POINT LAY WILL
REMAIN QUASI-STATIONARY FOR THE NEXT SEVERAL DAYS INTO AT LEAST
EARLY NEXT WEEK. A COLD UPPER LOW CENTERED OVER NORTHERN BANKS
ISLAND EARLY THIS MORNING DROPS SOUTH TODAY AND GETS SHEARED APART
AROUND THE UPPER RIDGE TONIGHT. THE MAIN PIECE OF ENERGY WITH THE
UPPER LOW EJECTS EAST ACROSS CANADA AND HEADS TOWARD NORTHERN HUDSON
BAY BY SATURDAY NIGHT. ANOTHER WEAKER PIECE OF THE LOW UNDERCUTS
THE RIDGE AND MOVES ACROSS THE NORTHERN INTERIOR FRI NIGHT INTO
SATURDAY...ENDING UP IN THE VCNTY OF THE BERING STRAIT BY SATURDAY
EVENING. THE MODELS ARE IN OVERALL GOOD AGREEMENT ON THIS IDEA.
AT THE SURFACE...A STRONG HIGH CENTERED NEAR 80N 150W WILL SLOWLY
SINK SOUTH THE NEXT COUPLE OF DAYS...REMAINING WELL OFF THE ARCTIC
COAST. ANOTHER RIDGE MAY SLIDE OUT OF SIBERIA SUN-MON AND WILL
LIKELY ACT TO KEEP THE RIDGE STRONG AND IN PLACE INTO TUES. A 970
MB LOW NEAR 50N 160W WILL WEAKEN AND SLOWLY LIFT TOWARD THE AK
PENINSULA BY SAT EVENING.
INTERIOR...THE PRESSURE GRADIENT WILL TIGHTEN UP ACROSS THE INTERIOR
TODAY BETWEEN THE LOW SOUTH OF THE STATE AND THE STRONG HIGH TO THE
NORTH. THE MODELS ARE IN GOOD AGREEMENT THAT OVERRUNNING SNOW
WILL DEVELOP FROM SOUTHEAST TO NORTHWEST ACROSS THE INTERIOR TODAY
INTO TONIGHT AS THE UPPER LOW PROVIDES A SHOT OF COLD AIR AND THE
LOW TO THE SOUTH PROVIDES THE MOISTURE. THIS WILL LEAD TO AN
INCREASING STRONG BAROCLINIC ZONE ACROSS THE AREA. AS THE UPPER
LOW MOVES OFF TOWARD THE BERING STRAIT BY SAT NIGHT IT WILL CAUSE
THE UPPER FLOW TO TURN INTO THE SOUTH ENDING THE SNOW. MANY AREAS
WILL LIKELY SEE A FEW INCHES OF SNOW...WITH LOCALLY HIGHER
AMOUNTS. STRONG NE-E WIND ACROSS THE HIGHER TERRAIN WILL PRODUCE
BLOWING SNOW ACROSS THE INTERIOR TODAY INTO SATURDAY. AS SNOW
MOVES IN FROM THE SOUTH...THE COMBINATION OF SNOW AND BLOWING
SNOW WILL PRODUCE POOR VISIBILITIES. WILL MAKES SOME CHANGES TO
THE ONGOING ADVISORIES FOR WIND AND REPLACE THEM WITH WINTER
WEATHER ADVISORIES FOR THE COMBINATION OF WIND...SNOW & BLOWING
SNOW.
WEST COAST...FAIRLY QUIET WEATHER TODAY INTO TONIGHT WITH SOMEWHAT
STRONGER WIND ALONG THE CHUKCHI SEA COAST WHERE THE PRESSURE
GRADIENT WILL BE THE STRONGEST. SOME OVERRUNNING SNOW EXPECTED
SATURDAY INTO SAT NIGHT AS THE UPPER LOW SLIDES ACROSS THE NORTHERN
INTERIOR TOWARD THE BERING STRAIT. IT LOOKS LIKE THE MOST LIKELY
AREAS TO PICK UP A FEW INCHES OF SNOW WILL BE ACROSS THE MIDDLE
YUKON VALLEY AND ACROSS THE NULATO HILLS. WILL INCREASE THE POPS
ACROSS MUCH OF THE WEST COAST AND START TO MENTION SOME SNOW
ACCUMULATION DURING THE 3RD PERIOD (SAT) IN ZONES 211-212-214-215-216.
POSSIBLE THAT SOME WINTER WEATHER ADVISORIES MAY BE NEEDED DOWN THE
ROAD FOR LATE SATURDAY INTO SATURDAY NIGHT.
NORTH SLOPE...LITTLE OR NO SNOWFALL EXPECTED THE NEXT FEW DAYS. A
MODERATELY STRONG PRESSURE GRADIENT WILL REMAIN AS THE SURFACE RIDGE
CONTINUES TO SLOWLY MOVE SOUTH. THE GRADIENT TIGHTENS A BIT MORE
HEADING INTO THE WEEKEND WHICH WILL LEAD TO BLOWING SNOW ALONG
MUCH OF THE ARCTIC COAST. THE LACK OF FALLING SNOW WILL LIKELY
PREVENT BLIZZARD CONDITIONS...BUT WILL NEED TO KEEP AN EYE ON
THINGS AS WINTER WEATHER ADVISORIES MAY NEED TO BE ISSUED SATURDAY
INTO SATURDAY NIGHT FOR LOW VISIBILITIES IN THE BLOWING SNOW.
COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FOR AKZ219-AKZ220-AKZ221-AKZ222.
GALE WARNING FOR PKZ225-PKZ230.
BRISK WIND ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ230-PKZ235-PKZ240-PKZ245.
&&
$$
CB DEC 09
