Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 271849
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
249 PM EDT FRI MAR 27 2015

.SYNOPSIS...
THE INTERACTION BETWEEN A WEAK SURFACE TROUGH...AND LOW PRESSURE
PASSING OFFSHORE...WILL PRODUCE CLOUDS AND A FEW SNOW SHOWERS
ACROSS THE AREA TONIGHT INTO SATURDAY. SHOWERS WIND DOWN SUNDAY AS
HIGH PRESSURE BUILDS IN FROM THE WEST. A PRE FRONTAL TROUGH
CROSSES THE REGION MONDAY FOLLOWED QUICKLY BY A COLD FRONT.
LOW PRESSURE CROSSES OVER SOUTHERN NEW ENGLAND LATE TUESDAY INTO
WEDNESDAY. MORE SIGNIFICANT PRECIPITATION IS POSSIBLE LATE NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
VERY SLOW BUT PROGRESSIVE UPPER TROF WILL SLOWLY DRIFT EAST FROM
THE EASTERN GREAT LAKES TONIGHT. ENOUGH CYCLONIC FLOW AND RESIDUAL
MOISTURE SHOULD SUFFICE IN DEVELOPING SCATTERED SNOW SHOWERS
TONIGHT AND BOUNDARY LAYER AND TEMPERATURES ALOFT WILL BE COLD
ENOUGH FOR PTYPE AS SNOW SHOWERS AFTER 00Z. AT THE SURFACE... MODELS
HINTING AT AN INVERTED TROUGH EXTENDING NORTHWEST INTO COASTAL
MAINE FROM SURFACE LOW WELL OUT TO SEA TO THE SOUTHEAST. THIS MAY
HELP ENHANCE ANY SNOW SHOWER ACTIVITY LATER TONIGHT INTO SATURDAY
BUT QPF OFF MODELS SUGGESTS MINIMAL AMOUNTS. USED A BLEND OF
MODELS FOR OVERNIGHT LOWS WHICH SHOULD RANGE FROM NEAR 20 IN THE
MOUNTAINS TO NEAR 30 ALONG THE COAST.

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
UPPER CYCLONIC FLOW CONTINUES AND WILL ALLOW SCATTERED SNOW
SHOWERS TO CONTINUE AS THE UPPER TROUGH CONTINUES TO SLOWLY DRIFT
ACROSS NEW ENGLAND SATURDAY. TEMPERATURES ALOFT ON SATURDAY AND
SATURDAY NIGHT COMBINED WITH COOLER BOUNDARY LAYER TEMPERATURES
WILL SUPPORT ANY PRECIPITATION TO BE IN THE FORM OF SNOW. NO
ACCUMULATIONS ARE EXPECTED WITH THIS SYSTEM AT THIS TIME ALTHOUGH
WOULD NOT BE SURPRISED TO SEE A FEW BURSTS OF STEADIER SNOW ALONG
PARTS OF SOUTHERN COASTAL AREAS. QPF AMOUNTS OFF MODELS ARE
MINIMAL AND ACCEPTED. SURFACE TEMPERATURES WILL BE IN THE 30S.

BY LATER SATURDAY NIGHT THE SYSTEM FINALLY EXITS TO THE EAST AND
CLEARING SHOULD BE NOTED FROM NORTHWEST TO SOUTHEAST.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
BY SUNDAY MORNING A LONGWAVE TROUGH AXIS WILL BE MOVING OFFSHORE.
SURFACE HIGH PRESSURE WILL HAVE ALREADY PUSHED INTO THE REGION
OVERNIGHT WITH W/NW SURFACE WINDS DAMMING THE COOLER AIR ALONG THE
MOUNTAINS AND ALLOWING DOWNSLOPING TO WARM THE COASTAL PLAIN MORE
DURING THE DAY. HIGHS SHOULD PEAK INTO THE LOWER TO MID 30S NORTH
TO UPPER 30S TO LOWER 40S ELSEWHERE. THE HIGH PRESSURE CENTER WILL
BE PUSHED TOWARDS THE DEEP SOUTH AS A STRONG SURFACE CYCLONE
DEEPENS AND APPROACHES THE GREAT LAKES LATE IN THE DAY. SOUTH
WINDS WILL DEVELOP AND PULL MOISTURE NORTHWARD BUT THIS SYSTEM
WILL BE SOMEWHAT MOISTURE-STARVED.

PRE FRONTAL TROUGH WILL CROSS THE REGION MONDAY NIGHT FOLLOWED
QUICKLY BY A COLD FRONT. THIS BRINGS SCATTERED LIGHT RAIN AND
SNOW TO THE REGION WITH THE RAIN/SNOW LINE LIKELY SETTING UP
SOMEWHERE IN THE FOOTHILLS. OROGRAPHIC LIFT SEEMS TO BE A KEY
PLAYER IN THIS SETUP WITH THE COASTAL PLAIN GETTING VERY LITTLE
QPF. SOME LINGERING SHOWERS ARE POSSIBLE INTO TUESDAY MORNING
ALONG THE INTERNATIONAL BORDER.

A WARM FRONT NEARS FROM THE WEST TUESDAY AFTERNOON WITH THE
STEERING FLOW KEEPING THE SYSTEM ON A EASTERLY TRACK. MODELS
VARY FROM JUST SKIRTING OUR AREA TO BRINGING AROUND A THIRD OF
AN INCH OF LIQUID PRECIPITATION TO SOUTHERN SECTIONS OF NH AND
SW MAINE THROUGH MIDDAY WEDNESDAY. A MORE SIGNIFICANT
PRECIPITATION EVENT IS POSSIBLE THURSDAY INTO FRIDAY WHICH COULD
POSE A TRAVEL THREAT FOR EASTER WEEKEND. HOWEVER CURRENTLY HAVE
LOW CONFIDENCE IN LONG TERM SOLUTIONS SO HAVE REMAINED WITH CHANCE
POPS.

AS FAR AS TEMPERATURES... WAVES OF MESOSCALE AS WELL AS SYNOPTIC
WARMING KEEP DAYTIME HIGHS HOVERING WITHIN A COUPLE DEGREES OF
NORMAL VALUES FOR PORTLAND AND CONCORD. OVERNIGHT MINIMUMS ALSO
SEEM TO BE NEAR THE MARK.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
SHORT TERM...VARIABLE MVFR CONDITIONS TONIGHT AND SATURDAY IN
SCATTERED SNOW SHOWERS.  VFR SATURDAY NIGHT.

LONG TERM...VFR CONDITIONS EXPECTED SUNDAY AS HIGH PRESSURE
BUILDS IN. A COLD FRONT WILL CROSS THE AREA MONDAY... WITH
SCATTERED MVFR CONDITIONS IN RAIN OR SNOW SHOWERS. SNOW SHOWERS
CONTINUE TO BE POSSIBLE FOR KHIE AND KLEB TUESDAY MORNING. TUESDAY
EVENING INTO EARLY WEDNESDAY MORNING LOW PRESSURE WILL IMPACT
SOUTHERN NH AND SW MAINE... BRINGING SCATTERED SNOW SHOWERS TO THE
REGION. KPSM MAY SEE RAIN INSTEAD.

&&

.MARINE...
SHORT TERM...
AN SCA FOR HAZARDOUS SEAS OVER THE OUTER WATERS HAS BEEN ISSUED
FOR LATER TONIGHT AND THROUGH SATURDAY NIGHT. SWAN WAVE MODELS
SHOWS SEAS BUILDING OVER THE OUTER WATERS THROUGH THAT TIME FRAME.

LONG TERM...WAVES DECREASE BELOW SCA CONDITIONS EARLY SUNDAY
MORNING. WINDS AND SEAS LOOK TO INCREASE ABOVE SCA THRESHOLDS
AGAIN EARLY MONDAY AHEAD OF NEXT COLD FRONT AND LAST JUST THROUGH
THE DAY.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 AM SATURDAY TO
     8 AM EDT SUNDAY FOR ANZ150-152-154.

&&

$$

MARINE/HANES


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