Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 300247 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1047 PM EDT MON JUN 29 2015 .SYNOPSIS... ABUNDANT LOW LEVEL MOISTURE FROM RECENT RAINFALL WILL ALLOW FOR SOME VALLEY FOG TO FORM OVERNIGHT. WEAK HIGH PRESSURE WILL MOVE INTO THE REGION FOR TOMORROW BEFORE ANOTHER LOW PRESSURE SYSTEM APPROACHES FROM THE WEST TOMORROW NIGHT AND WEDNESDAY. THE SYSTEM WILL BRING SHOWERS AND THUNDERSTORMS TO THE REGION ON WEDNESDAY BEFORE HIGH PRESSURE MOVES IN ON THURSDAY. HIGH PRESSURE THEN REMAINS IN PLACE INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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PREV DISC... JUST A COUPLE SPRINKLES REMAIN IN SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE. VERY LITTLE CHANGE TO THE CURRENT PACKAGE AS PATCHY FOG BEGINS TO DEVELOP OVER SHELTERED AREAS WITH PARTIAL CLEARING. UPDATE... HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS ACROSS MAINE AND NEW HAMPSHIRE. WILL CONTINUE TO KEEP A SLIGHT CHANCE OF SHOWERS IN THE FORECAST FOR ANOTHER COUPLE HOURS ACROSS WESTERN MAINE AND NEW HAMPSHIRE AS LIGHT PRECIP CONTINUES TO MOVE EASTBOUND PER LATEST RADAR IMAGERY. MOST OF THE LATEST SUITE OF MESOSCALE MODELS SHOW THE PRECIP DISSIPATING THIS EVENING. STRONG ONSHORE COMPONENT WILL CONTINUE TO WEAKEN THIS EVENING ALONG THE COAST. THIS KEPT TEMPERATURES MUCH COOLER RIGHT ALONG THE SHORELINE TODAY. ADDED MORE CLOUDINESS TO THE FORECAST AND MADE MINOR ADJUSTMENTS TO WINDS AND DEW POINTS. PREV DISC... FAIRLY QUIET NIGHT IN STORE. EXPECT CLOUD COVER TO QUICKLY DIMINISH AFTER SUNSET. RADIATIONAL COOLING...COUPLED WITH ABUNDANT LOW LEVEL MOISTURE FROM PREVIOUS RAINFALL...WILL ALLOW FOR SOME PATCHY FOG TO DEVELOP IN FAVORED LOCATIONS. EXPECT FOG TO FORM PRIMARILY IN VALLEYS AND ALONG COASTAL LOCATIONS.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... FOG SHOULD BURN OFF QUICKLY TOMORROW WITH SIGNIFICANT SUNSHINE BEING THE RULE FOR THE DAY. WEAK HIGH PRESSURE WILL NOT HOLD IN PLACE TOO LONG THOUGH. APPROACHING LOW PRESSURE SYSTEM MOVING THROUGH THE GREAT LAKES WILL BEGIN TO AFFECT THE WEATHER OVER NORTHERN NEW ENGLAND LATE TUESDAY NIGHT. AS FRONTAL BOUNDARY MOVES ACROSS CWA LATE TUESDAY NIGHT EXPECT SHOWERS TO FORM FROM SOUTH TO NORTH. DYNAMICS LOOK STRONG ENOUGH THAT THERE COULD BE SOME EMBEDDED THUNDER BY SUNRISE WEDNESDAY MORNING. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... WED LOOKS LIKE THE MOST INTERESTING DAY IN THE EXTENDED AT THIS TIME...AS STRONG S/WV TROF CROSSES THE NORTHEAST AND TRIGGERS AFTERNOON TSTMS. 50 KT H5 JET STREAK WILL CROSS THE AREA...PROVIDING AMPLE SHEAR. AT THIS RANGE SPC SREF INDICATES A HIGH LIKELIHOOD FOR 0-6 KM SHEAR TO FALL BETWEEN 30 AND 40 KTS...WHICH SHOULD LEAD TO SOME STORM ORGANIZATION. LAPSE RATES ARE A BIGGER QUESTION MARK...WITH THE ECMWF AND GFS ADVECTING MARGINAL 6 TO 6.5 C/KM LAPSE RATES OVERHEAD...WHILE THE NAM PREFERS MORE MEAGER VALUES. IF WE CAN REALIZE GREATER THAN 6 C/KM LAPSE RATES...SUFFICIENT INSTABILITY SHOULD BE IN PLACE FOR SOME STRONGER TSTMS. GUSTY WINDS AND HAIL WOULD BE THE MAIN THREATS...WITH WET BULB ZERO VALUES NEAR IDEAL FOR HAIL IN THE GYX FORECAST AREA PER LOCAL STUDIES. AS PWAT VALUES CLIMB OVER 1.5 INCHES NEAR THE COAST...CANNOT RULE OUT HEAVY RNFL IN ANY CONVECTION AS WELL. MAIN UPPER TROF AXIS SWINGS THRU THU...WHICH WILL ALLOW HIGH PRES TO BUILD IN FROM THE W FOR LATE IN THE WEEK AND HOLIDAY WEEKEND. AT THIS TIME...THE FINAL PUSH OF THE TROF LOOKS TO KEEP ANY PCPN WELL S OF THE REGION...BUT CANNOT REMOVE POP COMPLETELY ESPECIALLY FOR SRN AND COASTAL ZONES WITH ITS PASSAGE. ECMWF AND GFS NOW AGREE ON HIGH PRES TO BEGIN THE HOLIDAY WEEKEND...ALBEIT COOL HIGH PRES. HOWEVER...WITH WRN RIDGING STILL HOLDING STRONG THE TENDENCY WILL BE FOR LOWER HEIGHTS ACROSS THE ERN CONUS...AND RATHER FREQUENT S/WV ACTIVITY. THE NEXT APPEARS SET FOR LATE IN THE WEEKEND...MOST LIKELY SUN. FOR THE FORESEEABLE FUTURE TEMPS LOOK TO REMAIN NEAR TO BELOW NORMAL...WITH UNSETTLED WX CONDITIONS. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... SHORT TERM /THROUGH 12Z WED/...VFR CONDITIONS WILL DETERIORATE TO IFR/LIFR AT TAFS SITES WHERE VALLEY FOG IS FAVORED AT PATCHY FOG DEVELOPS OVERNIGHT. CONDITIONS WILL RAPIDLY IMPROVE TO VFR AT ALL LOCATIONS TOMORROW MORNING. APPROACHING FRONTAL BOUNDARY LATE TUESDAY NIGHT WILL BRING CIGS/VSBYS DOWN TO MVFR/IFR BY SUNRISE WEDNESDAY MORNING. LONG TERM...VFR EXPECTED TO GENERALLY PREVAIL THRU THE EXTENDED. COLD FRONT CROSSES THE AREA WED...WITH AREAS OF MVFR AND ISOLD IFR IN SHRA/TSRA. HIGH PRES LOOKS TO BUILD INTO THE REGION THRU THE HOLIDAY WEEKEND. ANOTHER TROF CROSSES THE AREA WITH SHRA POSSIBLE SUN. && .MARINE... SHORT TERM /THROUGH WEDNESDAY MORNING/...NO FLAGS EXPECTS. LONG TERM...WINDS AND SEAS GENERALLY LOOK TO REMAIN BELOW SCA THRESHOLDS. SWLY FLOW WILL INCREASE AHEAD OF THE NEXT COLD FRONT AND SEAS WILL BUILD TO NEAR 5 FT ON THE OUTER WATERS...THOUGH CONFIDENCE IS LOW IN REACHING THAT VALUE AT THIS TIME. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$

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