Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 180434 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1234 AM EDT SAT APR 18 2015 .SYNOPSIS... A WEAK LOW PRESSURE SYSTEM WILL DROP SOUTH AND EAST ACROSS THE REGION TONIGHT AND TOMORROW BRINGING SCATTERED SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS WITH IT. ANOTHER SYSTEM WILL APPROACH THE REGION ON MONDAY AND TUESDAY. THIS SYSTEM LOOK MUCH STRONG AND MAY BRING A SIGNIFICANT RAINFALL TO THE AREA. UNSETTLED WEATHER LOOKS TO DOMINATE THROUGHOUT NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1230 AM...MINOR ESTF UPDATE TO REFLECT CURRENT SATELLITE TREND...AND TO INGEST THE 04Z MESONET VALUES INTO 1ST PERIOD GRIDS. PREV DISC... 10PM...TEMPERATURES CONTINUE TO FALL RAPIDLY IN THE NORTHERN MOUNTAINS. ALSO DEWPOINTS ARE A BIT HIGHER THAN ANTICIPATED, MADE THESE ADJUSTMENTS AND DECREASED CLOUD COVER AS WAVE IS STILL QUITE A WAYS TO OUR NORTH IN QUEBEC. 6PM... MINOR UPDATE FOR CURRENT TEMPERATURES. FORECAST IS ON TRACK WITH CLEARING SKIES EXPECTED OVERNIGHT. MIDDAY DEWPOINTS WOULD SUPPORT FOG FORMATION OVERNIGHT IN A FEW VALLEYS...SUCH AS BERLIN AND KEENE... HOWEVER ADVECTION OF DRIER AIR FROM QUEBEC IS ONGOING SO EXPECT AIR TO DRY BEFORE ANY FOG WOULD FORM. PREV DISC BRIEF PERIOD OF QUIET WEATHER BETWEEN TODAYS SHOWERS AND THE NEXT SHORT WAVE THAT MOVES THROUGH TOMORROW MORNING. EXPECT TO SEE CLEARING SKIES ACROSS THE REGION. THIS WILL ALLOW FOR RADIATIONAL COOLING. WITH DEW POINTS DOWN IN THE 40S THOUGH...NOT SURE IF THERE WILL BE MUCH IN THE WAY OF FOG OR NOT. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SUNDAY/... SHORT WAVE DROPS SOUTH AND EAST OUT OF CANADA TOMORROW MORNING. MODELS HAVE SLIGHTLY DIFFERING SOLUTIONS WITH THIS FEATURE. THE GFS KEEPS THE MAJORITY OF THE ENERGY OVER THE NORTHERN HALF OF THE CWA. THE NAM HAS PRECIPITATION MORE WIDESPREAD WITH MOST OF THE AREA SEEING PRECIPITATION. SYSTEM SHOULD BE FAST MOVING THOUGH AND BY LATE TOMORROW AFTERNOON MOST OF THE THE AREA SHOULD BE DRY. DYNAMICS LOOK PRETTY GOOD FOR THIS TIME OF YEAR ALSO AND WOULD NOT BE SURPRISED TO SEE SOME ISOLATED THUNDER. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AFTER TRANSITIONING HIGH PRESSURE MOVES THROUGH ON SUNDAY... WINDS BECOME SOUTHERLY LATE SUNDAY NIGHT AS THE NEXT WAVE APPROACHES. A WARM FRONT SURGES UP FROM THE SW AS A STOUT SHORT WAVE ATTACHED TO THE MEAN CONUS TROUGH ROTATES INTO NEW ENGLAND BY LATE MONDAY. WARM ADVECTION SHOWERS SHOULD BEGIN AS EARLY AS MONDAY MORNING FROM WEST TO EAST. THE HEAVIER RAIN ARRIVES LATE MONDAY THROUGH TUESDAY AFTERNOON AS IT SHIFTS EAST. THIS COULD BE A HEAVY RAIN EVENT WITH A STRONG 50 KT LLJ CAUSING TRAINING OF CELLS AND FEEDING INTO SECONDARY LOW PRESSURE THAT WILL LIKELY FORM ALONG THE COAST TUESDAY. IN ADDITION FORECAST SOUNDINGS FOR PORTLAND INDICATE WARM RAIN PROCESSES. THIS DOES NOT EXCLUDE THE POSSIBILITY OF A COUPLE INCHES OF WET SNOW FOR THE MOUNTAINS. DRIER SW AIR PUNCHES IN BY TUESDAY NIGHT ALLOWING FOR PRECIPITATION EROSION FROM SW TO NE ACROSS NH AND CENTRAL ME THROUGH WEDNESDAY MORNING. HOWEVER ALMOST AS SOON AS THIS SYSTEM BEGINS TO EXIT INTO THE CANADIAN MARITIMES ANOTHER ONE ARRIVES. THIS OCCURS BECAUSE THE UPPER LEVEL LOW IS NOW NEARLY OVERHEAD AND A SERIES OF VORTICITY MAXIMA ARE ROTATING AROUND THE CENTER... RESULTING IN A MESSY WEEKEND IN THE NORTHEAST. WRAP AROUND MOISTURE FROM THE TUESDAY SYSTEM HELPS TO KEEP SHOWERS GOING THROUGH THE DAY WEDNESDAY. ANOTHER LOW PRESSURE SYSTEM DEVELOPS AND CROSSES THE REGION IN THE THURSDAY/FRIDAY TIME FRAME AND MAY FOCUS AN INVERTED TROF OVER THE REGION. THIS IS ANOTHER HEAVY RAIN SIGNAL. SO AT THIS TIME DETAILS MAY CHANGE BUT IT LOOKS LIKE A RAINY PERIOD IN THE EXTENDED. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...MVFR CONDITIONS SHOULD IMPROVE THIS AFTERNOON AND EVENING. PATCHY FOG MAY AFFECT A COUPLE OF STATIONS TONIGHT...BUT EXPECT MOSTLY VFR CONDITIONS. WEAK SYSTEM MOVES THOUGH TOMORROW WITH MVFR CIGS AND VSBYS AGAIN IN RAIN SHOWERS AND FOG. LONG TERM...VFR CONDITIONS SUNDAY INTO MONDAY MORNING. IFR CONDITIONS IN RAIN ARE LIKELY STARTING MONDAY AFTERNOON AND LASTING THROUGH WEDNESDAY. && .MARINE... SHORT TERM...NO FLAGS EXPECTED. LONG TERM...LOW PRESSURE AFFECTING THE WATERS MON NIGHT AND TUE WILL LIKELY BRING ROUGH SEAS AND SCA CONDITIONS...IF NOT LOW END GALES FOR A TIME. && .FIRE WEATHER... EXTREME SOUTHWESTERN PORTIONS OF THE CWA COULD SEE SOME RELATIVE HUMIDITY VALUES TOMORROW IN THE LOWER 30S. HOWEVER... THE LACK OF GUSTY WINDS AND POSSIBLE PRECIPITATION SHOULD KEEP CONDITIONS ABOVE RED FLAG CRITERIA. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES

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