Winter Storm in Maine, February 4 to 5, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
944 PM EST SUN FEB 3 2002

.UPDATED...
PREVIOUS FORECAST PACKAGE LOOKS GOOD. WILL ONLY UPDATE TO REMOVE EVENING
WORDING FOR COASTAL ZONES. FOR COASTAL WATERS...BASED ON LATEST BUOY
OBSERVATIONS...WILL ISSUE SCA FOR BOTH WINDS AND SEAS.

.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN QUEBEC WILL WEAKEN TONIGHT AS A BROAD AREA OF LOW
PRESSURE TAKES SHAPE IN THE GULF OF MAINE. A SURFACE TROUGH WILL CONNECT
THESE SYSTEMS...WHICH WILL FUNNEL MOISTURE FROM THE ATLANTIC INTO CENTRAL
AND DOWNEAST MAINE LATE TONIGHT AND MONDAY. DEVELOPING LOW PRESSURE IN THE
ATLANTIC WILL TAKE OVER ON MONDAY NIGHT. THIS LOW WILL INTENSIFY AS IT
MOVES FROM EAST OF NOVA SCOTIA...AND OFF INTO THE ATLANTIC. WEAK HIGH
PRESSURE WILL BRIEFLY RIDGE INTO THE REGION TUESDAY.

.DISCUSSION...
MODELS SHOW A DIFFICULT SYNOPTIC PATTERN SETTING UP...ONE WHICH MODEL QPF
FORECASTS TYPICALLY HAVE DIFFICULTY. ATTM...WE EXPECTING THE DEVELOPMENT OF
A NORLUN INSTABILITY TROF OVER DOWNEAST MAINE LATE TONIGHT AND MONDAY.
AVN/CANADIAN/ETA IN VERY GOOD AGREEMENT ON THE SYNOPTIC SET UP FOR THIS NEXT
SYSTEM. LOW PRESSURE OVER SOUTHERN QUEBEC WILL GRADUALLY FILL TONIGHT.
MEANWHILE...LOW PRESSURE WILL DEVELOP WELL OFF THE NEW JERSEY COAST THIS
EVENING...AND THEN WILL RAPIDLY INTENSIFY AS IT TRACKS TO THE SOUTH OF NOVA
SCOTIA. ALOFT...THE 850 LOW ASSOCIATED WITH THE S QUEBEC LOW WILL ALSO
FILL...LEAVING LIGHT WINDS AT THE 850 MB LEVEL LATE TONIGHT AND MONDAY. A
BROAD 500 MB TROF APPROACHES FROM THE WEST TONIGHT...WITH A COUPLE WEAK
SHORTWAVES CROSSING THE REGION...AND THE -35 C TEMPERATURE AXIS LIES JUST
INLAND.

ALL OF THIS POINTS TO A NORLUN EVENT. THE EASTERLY FLOW OF WARM MOIST
MARITIME AIR INTERACTING WITH THE COLD AIR ALOFT WILL RESULT IN
INSTABILITY...ENHANCING LIFT. THE KEY TO THIS IS WHERE THE SURFACE TROF
SETS UP. THE ETA/AVN SHOW THIS TROF INITIALLY SETTING UP FROM BAR HARBOR...
TO BANGOR...TO DOVER-FOXCROFT...AND THEN VERY GRADUALLY MIGRATING EAST. THE
HEAVIEST SNOW TYPICALLY FALLS JUST TO THE EAST OF THIS TROF. MODELS SHOW
HIGHEST QPFS OVER WASHINGTON COUNTY...WITH .3 TO .5 AMOUNTS. THE HIGHER
CANADIAN QPF SEEMS TO HAVE AN EXCELLENT HANDLE ON THIS MESOSCALE FEATURE.
PAST NORLUN EVENTS HAVE SHOWN THE FAVORED AREA FOR HEAVY SNOWS IS IN ZONES
29-15-16-31-11...AND BASED ON THE POSITION OF THE SURFACE TROF SHOWN BY THE
MODELS...WILL INCLUDE THESE ZONES...DESPITE WHERE THE MODELS SHOW THE QPF
BULLSEYE TO BE.

WILL UPGRADE WATCHES TO WARNINGS FOR DOWNEAST MAINE...EXPECTING THE
HEAVIEST SNOW TO FALL FROM 09 TO 23Z ON MONDAY. WILL GO WITH 4 TO 8 INCHES
OF SNOW...BUT CAN NOT RULE OUT LOCALLY HIGHER AMOUNTS...ESPECIALLY IF THE
TROF STALLS OVER A LOCATION. WILL ISSUE ADVISORIES IN ZONES 5-6-10 FOR 3 TO
6 INCHES OF SNOW.

MONDAY NIGHT...THE LOW EAST OF NOVA SCOTIA TAKES OVER...CUTTING OFF THE
ONSHORE FLOW. EXPECT SNOW TO COME TO AN END LATE MONDAY EVENING...WITH A
PARTIAL CLEARING FOR TUESDAY. FAVOR THE ETA/GEM TIMING ON THE NEXT VORT
MAX...WHICH WOULD BRING A CHANCE OF FLURRIES TUESDAY NIGHT. WILL FAVOR
WARMER MAV FOR LOWS TONIGHT...WITH A FWC/MAV COMPROMISE FOR THE REST OF THE
SHORT TERM.

LOOKING AHEAD...MRF/EUROPEAN/GEM/UKMET IN GOOD AGREEMENT THROUGH
THURSDAY. HERE MODELS SHOW A 500 MB TROF PROGRESSING TO THE EAST OF
MAINE ON WEDNESDAY...ALLOWING HIGH PRESSURE TO BRIEFLY RIDGE IN ON WEDNESDAY
NIGHT. THE NEXT SYSTEM...WHICH APPROACHES THURSDAY...IS A FAST MOVING
SYSTEM. SOME DISAGREEMENT HERE...ALL MODELS EXCEPT UKMET DO SHOW A
SYSTEM CROSSING NEAR MAINE ON THURSDAY...BUT DIFFER ON STRENGTH AND TRACK.
WILL TAKE CONSENSUS OF MRF/EUROPEAN/GEM WHICH WOULD BRING A CHANCE OF SNOW
THURSDAY AFTERNOON THROUGH FRIDAY MORNING. ALL MODELS SHOW HIGH PRESSURE
BUILDING IN FRIDAY NIGHT...WITH THE NEXT SYSTEM APPROACHING SATURDAY.
MRF/GEM BOTH SHOW A LOW PRESSURE DEVELOPING IN THE GULF OF MAINE SATURDAY
NIGHT. THE 168 HR EUROPEAN ALSO SUPPORTS THIS SOLUTION. BASED ON THIS WILL
INTRODUCE LIKELY POPS DOWNEAST...WITH A CHANCE OF SNOW UP NORTH FOR LATE
SATURDAY AND SUNDAY. WILL STICK CLOSE TO MEX FOR TEMPERATURES...EXCEPT
FEEL IT IS TOO COLD FOR THURSDAY NIGHT AND SATURDAY NIGHT.

COASTAL WATERS: GALE WARNING MAY BE NEEDED LATE MONDAY INTO TUESDAY...ON
THE HEELS OF THIS SYSTEM.

.CAR...WINTER STORM WARNING ZONES 11/15>17/29>32 LATE TONIGHT INTO
       MONDAY NIGHT.
       WINTER WEATHER ADVISORY ZONES 5/6/10 LATE TONIGHT INTO MONDAY NIGHT
       SCA

DW/JAH