Heavy Snow and High Wind in Alaska, January 14 to 15, 2007

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST SUN JAN 14 2007

.SHORT RANGE...LOW CONFIDENCE FORECAST TONIGHT AND MONDAY. MODELS
AND ENSEMBLE DATA ARE STILL ALL OVER THE PLACE WITH THE
INTENSITY...TIMING...AND TRACK OF A LOW DEVELOPING OVER THE
NORTHEAST PACIFIC THAT MOVES NORTH INTO THE EASTERN GULF LATE
TONIGHT AND MON. NOT ENOUGH OBS IN THAT REGION TO HELP INITIALIZE
HOW THE LOW IS STARTING TO DEVELOP. HAVE OPTED TO TAKE THE SLOWER
NAM/UKMET TRACK BUT ONLY DEEPEN THE LOW INTO THE 990S LIKE THE
NAM AS OPPOSED TO THE EXTREME SOLUTION OF THE UPPER 980S THAT THE
UKMET HAS. THEREFORE...WILL DEEPEN A LOW INTO THE MID 990S AS IT
MOVES WEST OF THE QUEEN CHARLOTTES AND OFF THE SOUTHWEST COAST OF
THE PANHANDLE THROUGH MON MORNING. THE LOW WILL MOVE INTO THE
SOUTHERN YUKON AND NORTHERN BRITISH COLUMBIA MONDAY AFTERNOON.

A SUBTROPICAL FEED INTO THE SYSTEM WILL SPREAD A MILD AIRMASS
NORTH INTO THE PANHANDLE TONIGHT AND EARLY MON RESULTING IN HEAVY
RAIN AT TIMES OVER THE CENTRAL AND SOUTHERN PANHANDLE. THE HYDER
AREA IN ZONE 29 IS GOING TO BE VERY DIFFICULT WITH PRECIP TYPE.
STILL IN THE 20S AND SNOWING THERE WITH A GOOD SOUTHERLY FLOW NOT
EXPECTED UNTIL MON AFTERNOON. QPF AMOUNT IN THAT REGION WILL GET
INTO THE 1 TO 2 INCH TONIGHT THROUGH MONDAY MORNING. THINK IT
WILL BE HARD TO GET A WARMER ENOUGH AIRMASS IN THERE TO CHANGE IT
OVER RAIN UNTIL THE GOOD SOUTHERLY FLOW DEVELOPS...SO WILL
UPGRADE THE WATCH TO A WARNING.

ELSEWHERE...EXPECT MAINLY RAIN THROUGH MONDAY WITH THE NORTHERN
EDGE OF THE PRECIP POSSIBLY JUST MAKING UP INTO THE HAINES AND
SKAGWAY AREAS WHERE PRECIP COULD GO BACK TO SNOW LATE TONIGHT OR
EARLY MON AS VERY WEAK NORTHERLY FLOW RETURNS. IT IS STILL LIKELY
THAT A DEFORMATION BAND NORTH AND WEST OF THE LOW MAY BRING A
BAND OF HEAVIER PRECIP TO A PORTION OF THE NORTH OR CENTRAL
PANHANDLE ON MON WHERE WEAK FLOW EXISTS. HOWEVER CONFIDENCE IS
LOW AS TO WHERE THIS BAND WILL GO AND IF IT WILL BE STRONG ENOUGH
TO BRING HEAVY SNOW TO WARRANT HEAVY SNOW WARNINGS. WILL BE
SLOWING DOWN THE NORTHWARD PROGRESSION OF THIS SYSTEM SO MAY
LEAVE THE WATCH OUT FOR MONDAY. THIS SYSTEM WILL BE TOO FAR EAST
TO EFFECT THE NORTHEAST GULF COAST (YAKUTAT) BUT A LINGERING LOW
OVER THE NORTHWEST GULF WILL KEEP SOME SHOWERS OVER THE AREA
THROUGH MON THAT WILL TRANSITION TO SNOW SHOWERS MONDAY MORNING
AS A COLDER AIRMASS MOVES ACROSS THE GULF.

SOUTHWEST FLOW AT ALL LEVELS BEHIND THIS SYSTEM WILL SPREAD A
COLDER AIRMASS INTO THE ENTIRE PANHANDLE EARLY MON EVENING AND
TRANSITION ALL AREAS TO SNOW SHOWERS.

WIND...THE LOW WILL BRING WIND ADVISORY GUSTS TO THE SOUTHERN
PANHANDLE TONIGHT AND MON. THE MAIN CONCERN WILL BE IF THE LOW
DOES IN FACT GET DEEPER WHICH WOULD RESULT IN HIGH WIND WARNING
GUSTS ON MON. DUE TO LOTS OF UNCERTAINTY WILL GO MAX ADVISORY.

.LONG RANGE...
BIG DILEMMA TODAY WAS TRACK AND DEPTH OF SECONDARY LOW DEVELOPING
ON FRONT NEAR 47N 146W AT 18Z SUN. CONSENSUS HERE WAS TO USE NAM
THROUGH 00Z THU TO ACCOUNT FOR SLOWER MOVEMENT OF LOW PLUS MORE
DEVELOPMENT. UPPER RIDGE BUILDS OVER WESTERN GULF TUE AS PER ALL
MODELS AND SEVERAL RUNS. EXPECT RIDGE AXIS OVER CENTRAL GULF 00Z
WED WITH THE FIRST IN A SERIES OF SHOWRTWAVES BUSTING THRU THE
RIDGE BY 18Z WED OR SO. BEST GUESS OF RIDGE KICKING OUT EAST OF
PANHANDLE BY 12Z THU BUT CONFIDENCE LOW IN LONGER TERM DETAILS
DUE TO DIFFICULTY IN PREDICTING EFFECTS OF SHORTWAVES IN THIS
PATTERN.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WINTER STORM WATCH 18-20 22 29 LATE TONIGHT-MON
         SNOW ADV 29 TODAY
         WIND ADV 27-29

MARINE...GALES 43 51 52. ALL OTHER MARINE ZONES SCA.

TAR/JC