AFDCAR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
855 AM EDT MON APR 18 2011

.SYNOPSIS...
A COLD FRONT WILL SWEEP ACROSS THE AREA TODAY...FOLLOWED BY HIGH
PRESSURE FOR TUESDAY. LOW PRESSURE IS EXPECTED TO MOVE OUT OF THE
GREAT LAKES REGION ON WEDNESDAY AND THROUGH SOUTHERN QUEBEC
WEDNESDAY NIGHT INTO THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE UPPER TROUGH THAT BROUGHT SNOW TO THE AREA OVERNIGHT IS MOVING
INTO NEW BRUNSWICK THIS MORNING. THE ASSOCIATED PRECIPITATION HAS
ALSO EXITED THE FORECAST AREA WITH JUST A FEW SHOWERS STILL
SHOWING UP ON RADAR. HAVE THEREFORE ISSUED AN UPDATE TO LOWER
PRECIP CHANCES OVER NORTHERN AREAS. OTHERWISE THE GOING FORECAST
LOOKS GOOD AND NO OTHER CHANGES WERE NEEDED.

PREVIOUS DISCUSSION...
INTENSE LOW PRESSURE OVER CENTRAL QUEBEC PROVINCE WILL CONTINUE TO
MOVE TO THE NORTHEAST TODAY. UPPER LEVEL TROF IS EXPECTED TO MOVE
ACROSS THE NORTHERN PORTION OF THE STATE THIS MORNING. THIS WILL
RESULT IN SNOW SHOWERS EARLY THIS MORNING AND THEN RAIN SHOWERS
LATER IN THE DAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST
TONIGHT. HAVE USED A BLEND OF THE NAM12...GFS40 AND SREF TO
INITIALIZE POP GRIDS....WILL INCREASE POPS TO CATEGORICAL ACROSS
THE NORTHWEST THIS MORNING. RADAR ALREADY SHOWING SNOW/RAIN
SHOWERS OCCURRING. FOR WIND...TEMPERATURE AND DEW POINT WILL
INITIALIZE GRIDS WITH GMOS. WILL DECREASE GMOS TEMPERATURE EARLY
THIS MORNING AND WILL INCREASE GMOS MINIMUMS TOMORROW MORNING. FOR
QPF WILL USE BLEND OF NAM AND GFS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
ANOTHER STORM SYSTEM EXPECTED TO AFFECT THE REGION BY WEDNESDAY.
CHALLENGE WILL BE PRECIP TYPE AND QPF.

ON TUESDAY...THE COLD FRONT SLIDES OFF THE COAST W/A WAVE OF LOW
PRES MOVING NE ALONG THE BOUNDARY THROUGH THE GULF OF MAINE. DRY
FOR MOST OF THE CWA AND STILL BELOW NORMAL FOR MID APRIL. RIGHT
ALONG THE COAST... THE DECISION WAS TO KEEP HIGH CHC TO LIKELY
POPS(50-60%) RIGHT USING A BLEND OF THE GFS/SREF FOR POPS. THE
WAVE QUICKLY ZIPS TO THE EAST TUESDAY EVENING W/HIGH PRES MOVING
IN FROM CANADA. THIS HIGH WILL BRING COOLER AND DRIER AIR TO THE
CWA TUESDAY NIGHT. DECIDED TO STAY CLOSE TO THE DAYCREW/S
TEMPERATURES BOTH TUESDAY AND TUESDAY NIGHT INDICATING A CHILLY
NIGHT TUESDAY NIGHT W/TEMPERATURES SOME 10 DEGREES BELOW NORMAL
ESPECIALLY ACROSS THE NORTHERN 1/2 OF THE CWA WHERE CLEAR
CONDITIONS WILL ALLOW FOR DECENT RADIATIONAL COOLING.

ON WEDNESDAY...LOW PRES SHOWN BY THE GFS/GFS ENSEMBLE AND THE NAM
TO MOVE UP THROUGH ONTARIO W/COLD AIR DAMMING SETTING UP. THE
ECMWF HAS TRENDED FURTHER WEST W/THE LOW BUT CONTINUES TO SHOW A
SECOND LOW DEVELOPING NEAR THE MAINE COAST AND MOVING INTO NEW
BRUNSWICK. THIS WOULD MEAN COLDER SOLUTION W/FROZEN PRECIP HOLDING
ON LONGER.

FOR NOW...BLENDED THE NAM/GFS AND GMOS FOR POPS WHICH SHOWS
CATEGORICAL(80%) BY WEDNESDAY AFTERNOON. TWEAKED TEMPERATURES UP
SOME INITIALLY BUT EVAPORATIVE COOLING WILL ALLOW FOR INITIAL
RAIN TO GO TO SNOW ACROSS THE NORTH AND WEST AND EVEN FAR SOUTH AS
THE CENTRAL HIGHLANDS INCLUDING THE GREENVILLE AND DOVER-FOXCROFT
REGION W/TEMPERATURES DROPPING BACK INTO THE 30S BY LATE AFTERNOON.
MODEL SOUNDINGS AND PARTIAL THICKNESS SCHEMES SUGGEST SNOW W/EVEN A
MIX OF SLEET OR A CHANGEOVER TO SLEET LATE IN THE DAY. ACROSS THE
DOWNEAST AND THE COAST AREAS..ANY FROZEN PRECIP WILL GO TO RAIN.
HEAVIEST WAS SITUATED ACROSS THE NORTH USING THE GFS/GMOS/SREF
BLEND.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
LOW PRES CONTINUES TO THE NE THROUGH QUEBEC WEDNESDAY NIGHT DRAGGING
AN OCCLUDED FRONT THROUGH THE REGION AND WARMER AIR NORTHWARD. ANY
FROZEN PRECIP ACROSS THE NORTH IS EXPECTED TO GO TO RAIN AS WAA
TAKES HOLD. PRECIP WILL WIND DOWN BY THURSDAY MORNING AS A DRY
SLOT MOVES ACROSS THE CWA. DECIDED TO CUT POPS BACK TO CHC BY
THURSDAY MORNING DUE TO THE DRY SLOTTING. ASSOCIATED COLD FRONT
WILL DRIVE ITS WAY ACROSS THE REGION BY THURSDAY AFTERNOON W/CAA
AND MORE SHOWERY PRECIP. USED THE GMOS POPS BUT ADJUSTMENTS WERE
MADE TO THURSDAY TO CUT THEM BACK W/LITTLE IN THE WAY OF FORCING
AND BEST DYNAMICS IN NEW BRUNSWICK. TEMPERATURES WILL LEVEL OFF
EARLY AND THEN FALL BACK DURING THE AFTERNOON. FOLLOWED GMOS FOR
THURSDAY INTO FRIDAY BUT ADJUSTED THURSDAY AFTERNOON TEMPERATURES
DOWN A BIT W/CAA. WINDS WILL PICK UP BEHIND THE FRONT W/GUST
POTENTIAL OF 35+ MPH INTO THURSDAY EVENING. DECENT SHOT OF QPF
CLOSE TO AN INCH ACROSS THE NORTHERN 3RD OF THE CWA USING THE
BLEND MENTIONED IN THE SHORT TERM.

ATTM...WE ARE NOT ANTICIPATING ANY FLOODING PROBLEMS ALTHOUGH
RIVER LEVELS WILL RISE IN RESPONSE TO THE QPF. THIS HOWEVER WILL
NEED TO BE MONITORED BY SUBSEQUENT SHIFTS.

HIGH PRES IS EXPECTED TO MOVE INTO THE REGION ON FRIDAY W/DRIER
CONDITIONS BUT THIS LOOKS TO BE SHORT LIVED AS YET ANOTHER
POTENTIAL STORM SYSTEM COULD AFFECT THE CWA OVER THE WEEKEND. BOTH
THE GFS AND ECMWF INDICATE THIS SYSTEM TO BE A FAST MOVER BUT
ADDITIONAL QPF OF UP TO .50 INCH COULD LEAD TO SOME HYDRO
CONCERNS. STILL SOME TIME TO ASSESS THIS W/THE LATER GUIDANCE.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
NEAR TERM: MVFR/VFR CONDITIONS ARE EXPECTED THIS MORNING AND VFR
CONDITIONS THIS AFTERNOON AND TONIGHT IN NORTH. FOR SOUTH EXPECT
VFR CONDITIONS NEXT 24 HOURS.

SHORT TERM: VFR THROUGH TUESDAY NIGHT FOR THE ENTIRE TAF REGION
W/THE EXCEPTION FOR KBHB EARLY TUESDAY AS CIGS/VSBYS COULD BE
DOWN TO MVFR AS LOW PRES PASSES THROUGH THE GULF OF MAINE.

FOR WEDNESDAY INTO THURSDAY...LOOK FOR CONDITIONS TO DROP TO MVFR
EARLY WEDNESDAY DOWN TO IFR BY WEDNESDAY AFTERNOON INTO THE
EVENING FOR ALL TAF SITES. IMPROVEMENT ON THURSDAY FOR KBGR/KBHB
TO VFR BUT AT LEAST MVFR FOR THE NORTHERN TAF SITES.

&&

.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 FOR WIND
GRIDS. FOR WAVES: WITH LONG FETCH IN ADVANCE OF LOW YESTERDAY
EXPECT LONG PERIOD WAVE TO PERSIST. HAVE USED THE SWAN/NAM TO
GENERATE GRIDS. WILL EXTEND THE SCA INTO THIS EVENING.


SHORT TERM: SCA POSSIBLE BY WEDNESDAY RIGHT INTO THURSDAY STARTING
OUT FOR SEAS ON WEDNESDAY AND THEN GOING TO WINDS/SEAS LATER
WEDNESDAY NIGHT THROUGH THURSDAY. DAYCREW/S WIND/SEAS LOOKED GOOD
MATCHING THEM UP TO THE NAM12 AND GFS WINDS AND WNAWAVE.
ADJUSTMENTS WERE MADE HOWEVER FOR THURSDAY TO BRING WINDS UP IN
RESPONSE TO NW WINDS OF 40-50KT FROM 925-850MBS AND CAA.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 PM EDT THIS EVENING FOR
     ANZ050>052.

&&

$$
NEAR TERM...HASTINGS/MIGNONE