Area Forecast Discussion
Issued by NWS Portland, ME

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478 FXUS61 KGYX 021049 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 649 AM EDT MON MAY 2 2016 .SYNOPSIS... AS ONE AREA OF RAIN DEPARTS THE AREA EARLY THIS MORNING ANOTHER WILL FOLLOW ON ITS HEELS FOR THIS AFTERNOON. THE UNSETTLED WEATHER WILL TRY AND STAY SOUTH OF THE AREA TUESDAY...BEFORE RETURNING AGAIN FOR LATE IN THE WEEK. AN UPPER LEVEL LOW PRESSURE SYSTEM LOOKS TO SETTLE INTO THE MID ATLANTIC INTO THE WEEKEND. THIS WILL PROVIDE A FEW DAYS OF COOLER...ONSHORE FLOW AND SHOWERY WEATHER. && .NEAR TERM /TODAY/...
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645AM UPDATE... HAVE FURTHER REFINED EARLY MORNING PRECIPITATION CHANCES BASED ON LATEST RADAR TRENDS. AREA OF SHOWERS JUST WON`T QUIT AS NEW ACTIVITY KEEPS REGENERATING. HOWEVER... THE OVERALL TREND OF SHOWERS MOVING TO THE EAST IS STILL CLEAR... EVEN IF THE PROGRESSION IS SLOWER THAN ANTICIPATED. SHOULD SEE THE NEXT ROUND OF RAIN ARRIVING IN WESTERN NEW HAMPSHIRE AROUND 11AM. ORIGINAL DISCUSSION... THE FORECAST FOR THE NEXT SEVERAL DAYS WILL FEATURE SEVERAL SHORTWAVE TROUGHS CROSSING THE AREA... EACH ONE A LITTLE FURTHER SOUTH IN ITS TRACK THAN THE LAST. THE FIRST IN A SERIES OF SHORTWAVE TROUGHS IS EXITING TO THE EAST EARLY THIS MORNING... BUT THE NEXT ONE IS ALREADY APPROACHING FROM THE WEST. SO WHILE SHOWERY WEATHER WILL LIKELY DIMINISH FOR A FEW HOURS EARLY THIS MORNING... ANOTHER ROUND OF RAIN IS EXPECTED TO ARRIVE FROM WEST TO EAST LATE THIS MORNING AND THROUGH THE AFTERNOON. IN ADDITION... A PERSISTENT EAST/SOUTHEAST LOW LEVEL FLOW WILL CONTINUE TO ADVECT MOISTURE IN OFF THE GULF OF MAINE LEADING TO AREAS OF FOG AND DRIZZLE THROUGH THE MORNING. TEMPERATURES TODAY WILL BE COOL WITH THE ONSHORE FLOW...CLOUD COVER... AND RAIN. WENT A LITTLE BIT BELOW MOST OF THE FORECAST MODEL GUIDANCE FOR TEMPERATURES THIS AFTERNOON AS IT WILL BE VERY DIFFICULT FOR MOST OF US TO GET OUT OF THE 40S.
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&& .SHORT TERM /TONIGHT THROUGH TUESDAY/... THE SHORTWAVE TROUGH AND ASSOCIATED WEAK SURFACE LOWS WILL MOVE EASTWARD TONIGHT... TAKING THE STEADIER RAIN WITH IT. HIGH PRESSURE BRIEFLY BUILDS IN BEHIND IT BUT ANOTHER TROUGH WILL BE MOVING TOWARD THE AREA FROM THE SOUTHWEST BY TUESDAY MORNING. THIS ONE WILL BE FAR ENOUGH SOUTH THAT ONLY SOUTHERN NEW HAMPSHIRE AND PERHAPS COASTAL MAINE ARE AFFECTED WITH SOME LIGHT RAIN. BUT IT WILL HELP TO KEEP AN EASTERLY FLOW OVER THE GULF OF MAINE AND INTO NORTHERN NEW ENGLAND... KEEPING TEMPERATURES COOL ONCE AGAIN. RAW MODEL OUTPUT HAS TEMPERATURES ONLY IN THE UPPER 40S TUESDAY WHILE MOST OF THE MOS TRIES TO WARM THINGS UP MORE. DECIDED TO GO CLOSER TO THE RAW MODEL OUTPUT GIVEN THE ONSHORE FLOW AND CLOUD COVER. HOWEVER... ON THE OTHER SIDE OF THE MOUNTAINS TEMPERATURES COULD WARM INTO THE 60S. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... THE EXTENDED FORECAST LOOKS A BIT LIKE A PUBLIC SERVICE ANNOUNCEMENT FOR THE DANGERS OF SPRING IN NEW ENGLAND. DETERMINISTIC AND ENSEMBLE MODEL GUIDANCE ARE CONSISTENT WITH THE DEEPENING OF AN ERN CONUS TROF...WITH EVENTUAL CUT OFF LOW FORMATION TO OUR SW. A LEAST A FEW DAYS OF MOIST ONSHORE FLOW...AND SHOWERY WX ARE LOOKING MORE LIKELY. FAVORED BLENDING IN A LITTLE MORE RAW MODEL GUIDANCE TO THE MULTI-MODEL CONSENSUS...AS MOS RELATED PRODUCTS ARE LIKELY BRINGING TEMPS UP TOO MUCH GIVEN THE EXPECTED CLOUD COVER AND PRECIP IN THE AREA. AT THE SAME TIME...POP IS DIFFICULT TO NAIL DOWN...AS NO ONE PERIOD IS LOOKING MORE OR LESS LIKELY FOR RNFL AT THIS TIME. IT DOES APPEAR THAT A STRONGER S/WV MAY TRY AND PASS THE AREA THU...BUT PROXIMITY OF THE UPPER LOW MAY ALSO FAVOR DIURNAL INCREASES IN SHOWERS WITH COLD TEMPS ALOFT. THE RELATIVELY LOWER HEIGHTS ALOFT LOOK TO CONTINUE INTO EARLY NEXT WEEK...EVEN IF THE UPPER LOW LIFTS OUT. THE TREND OF COOLER THAN NORMAL HIGH TEMPS AND ABOVE NORMAL CHANCES FOR PRECIP SHOULD CONTINUE FOR THE FIRST WEEK OF MAY...SO THE CALENDAR MAY HAVE CHANGED MONTHS BUT IT DOESN/T LOOK LIKE THE WX PATTERN HAS. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... SHORT TERM...AREAS OF FOG AND DRIZZLE WILL KEEP CONDITIONS IFR OR WORSE THROUGH THE MORNING. THEN THE RAIN MOVES IN LATE MORNING THROUGH THE AFTERNOON WITH CONTINUED IFR CONDITIONS. MAY SEE A BRIEF BREAK IN THE CLOUDS THIS EVENING AS THE LOW MOVES OUT... BUT WITH ALL THE RAIN THAT FALLS TODAY ANY CLEARING WILL JUST BE GROUNDS TO CAUSE FOG TO FORM AGAIN WITH NOCTURNAL COOLING IN THE MOIST SURFACE AIR. LONG TERM...UNDER THE INFLUENCE OF AN UPPER LOW PRES SYSTEM...CLOUDS AND SHRA WILL REMAIN IN THE FORECAST THRU THE END OF THE WEEK. AREAS OF MVFR AND LOCAL IFR WILL BE POSSIBLE IN SHRA...AS WELL AS ANY MARINE FOG AND STRATUS. && .MARINE... SHORT TERM...ALTHOUGH WINDS REMAIN RELATIVELY LIGHT TODAY... AN INCREASING EASTERLY FLOW TO THE NORTH OF DEVELOPING LOW PRESSURE OFFSHORE WILL BEGIN GENERATING WAVES WHICH WILL HEAD WESTWARD INTO THE GULF OF MAINE THIS EVENING. WAVE HEIGHTS ARE EXPECTED TO BE AROUND 5 FEET SO A SMALL CRAFT ADVISORY FOR SEAS HAS BEEN ISSUED THIS EVENING. LONG TERM...A PERSISTENT AREA OF LOW PRES TO OUR S WILL BRING NE FLOW ON THE WATERS INTO THE WEEKEND. WHILE WINDS LOOK TO REMAIN BELOW SCA THRESHOLDS...LONG DURATION NE FLOW MAY BUILD SEAS OUTSIDE THE BAYS TO NEAR 5 FT LATE IN THE WEEK. && .FIRE WEATHER... WEATHER PATTERN THIS WEEK WILL BE PRETTY CONSISTENTLY MOIST WITH AN ONSHORE FLOW AND MULTIPLE OPPORTUNITIES FOR RAINFALL. && .TIDES/COASTAL FLOODING... BEGINNING THURSDAY THROUGH THE WEEKEND...WE ARE SET FOR A PERIOD OF HIGH ASTRONOMICAL TIDES. THE HIGHEST TIDES WILL BE FRIDAY AND SATURDAY NIGHTS WHEN PORTLAND IS FORECAST TO REACH 11.9 FEET AT 1135 PM AND 1226 AM RESPECTIVELY. COASTAL FLOODING MAY BE POSSIBLE DURING THIS TIME PERIOD...AS WINDS WILL GENERALLY BE EASTERLY TO NORTHEASTERLY. IF LOW PRESSURE DEVELOPS A LITTLE SOONER OR STRONGER...COASTAL FLOODING ISSUES COULD BEGIN AS EARLY AS THE THURSDAY EVENING TIDE. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 4 PM THIS AFTERNOON TO 6 AM EDT TUESDAY FOR ANZ150-152-154. && $$ NEAR TERM...KIMBLE SHORT TERM...KIMBLE LONG TERM...LEGRO AVIATION...KIMBLE/LEGRO MARINE...KIMBLE/LEGRO FIRE WEATHER...KIMBLE TIDES/COASTAL FLOODING...LEGRO

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