Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 282139 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 539 PM EDT MON JUL 28 2014 .SYNOPSIS... LOW PRESSURE WILL TRACK THROUGH NORTHERN NEW ENGLAND AND INTO EASTERN CANADA TONIGHT. A TRAILING COLD FRONT WILL SLIDE OFF THE COAST TONIGHT THEN REMAIN NEARLY STATIONARY TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE BUILDS ACROSS THE REGION THRU THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... WILL UPDATE TO INPUT LATEST OBSERVED DATA. ADJUSTED CHC OF PRCP THIS EVE PER LATEST RADAR LOOP. OTRW JUST MINOR TWEAKS. SVR TSTM WATCH NUMBER 452 IN EFFECT THRU 8 PM FOR ALL OF OUT NH ZONES AND ALL BUT OUR MOST ERN ZONES IN ME. THREAT IS FOR LARGE HAIL AND DAMAGING WINDS. EVEN AN ISOLATED TORNADO CAN NOT BE RULED OUT. ALSO...ANY TORRENTIAL RAIN THAT FALLS ON TOP OF SIGNIFICANT RAINFALL THAT HAS ALSO FALLEN COULD LEAD TO LOCALIZED FLASH FLOODING. THE SFC LOW TRACKS TO THE N NE MOVING ACROSS NH AND FAR NW MAINE THEN INTO ERN CANADA TNGT. A TRAILING COLD FRONT WORKS ITS WAY E ACROSS THE FCST AREA...PUSHING JUST OFFSHORE BY DAYBREAK. THE LOW AND FNT PROVIDE THE FOCUS FOR THE SHRA/TSTM ACTIVITY. VERY MOIST AIR IN PLACE AS INDICATED BY SFC DEW POINTS...850 MB DEW POINTS AND PWAT VALUES. THIS SUPPORTS THE HEAVY RAIN POTENTIAL INTO THIS EVE. INSTABILITY AND SPEED AND DIRECTIONAL SHEAR ALONG WITH DYNAMICS FROM STRONG UPPER LVL TROF LIFTING OUT TO THE NE ACROSS THE REGION PROVIDE THE FOCUS FOR SVR CONVECTION. AFTER THIS EVE...STILL SHRA AND MAYBE A TSTM AROUND WITH PASSAGE OF FNT. DUE TO ALL THE RECENT RAINFALL SHOULD BE AREAS OF DENSE F AROUND...ESPECIALLY FOR AREAS AHEAD OF THE FNT. THE FNT IS FOLLOWED BY A WIND SHIFT TO THE W NW BUT WINDS MAY NOT PICK UP ENOUGH TO SCOUR OUT THE LOW LVL MOISTURE AND F. USED A BLEND OF MODELS AND MOS GUIDANCE FOR THE NEAR TERM FCST. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... AS THE SFC LOW MOVES WELL INTO ERN CANADA THE UPPER LVL FLOW REMAINS FROM THE SW AS AN UPPER LVL CUTOFF LOW REMAINS OVER OR JUST N OF THE GREAT LAKES. THIS KEEPS THE SFC COLD FNT FROM MOVING MUCH MORE TO THE E...IN FACT IN MAY MOVE BACK TO THE W. THE FNT IS WEAKENING AND WILL THEREFORE NOT PROVIDE SUPPORT FOR ANY PRCP... ESPECIALLY WITH DRIER AND MORE STABLE AIR MOVING INTO THE REGION AS THE DRY WEDGE WRAPS ALL THE WAY AROUND THE UPPER LVL CUTOFF LOW AND UP THE ERN SEABOARD. HIGHS IN THE 70S ON TUESDAY AS DEW POINTS DROP INTO THE 50S. THIS LEADS TO COOL OVERNIGHT LOWS TUESDAY NGT FROM THE 40S N TO THE 50S S. USED A BLEND OF MODELS AND MOS GUIDANCE FOR THE SHORT TERM FCST. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... 500 MULTIPLE OMEGA BLOCK PATTERN WILL HOLD FROM THE PACIFIC EWD ACROSS THE CONUS AND INTO THE ATLANTIC....ALTHOUGH AMPLITUDE WILL SLOWLY WEAKEN TOWARD THE END OF THE WEEK AND THROUGH THE WEEKEND. SO...THE COOLER AND DRIER AIR WILL GRADUALLY SHIFT NWD AND BE ME REPLACES MORE LOW LVL MOISTURE AND SLIGHTLY WARMER TEMPS. THE TREND WILL BE FOR HIGHS RUNNING NEAR NORMAL...AND MINS SLIGHTLY ABOVE NORMAL. COULD SEE A WAVE MOVE THROUGH THE SW FLOW ALOFT AND MAYBE BRING A THREAT OF SCT SHRA/TSRA...ESPECIALLY IN THE MTNS. FOR NOW THIS LOOKS TO BE CENTERED AROUND FRIDAY...AND THEN ANOTHER ROUND SUN NIGHT INTO MON...AS PERHAPS A MORE SIGNIFICANT WAVE PUSHES THE 500 TROUGH SWD. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... SHORT TERM /THROUGH TUESDAY NIGHT/...VARIABLE CONDITIONS FROM MVFR TO LIFR THRU THE NGT DUE TO SHRA/TSTM ACTIVITY WITH THE POTENTIAL FOR SVR TSTMS THRU 8 PM THIS EVE. AREAS OF F AROUND NRN/ERN AREAS WILL BECOME MORE WIDESPREAD OVERNIGHT. CONDITIONS IMPROVE TO VFR FOR TUESDAY AND TUESDAY NGT. LONG TERM...MAINLY VFR...EXCEPT FOR EARLY MORNING VLY FOG//WED THRU SATURDAY. && .MARINE... SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...UPDATED TO INPUT LATEST OBSERVED DATA RESULTING IN NO MORE THAN A FEW MINOR ADJUSTMENTS TO THE FCST FOR TNGT. WILL CONT THE SCA FOR TNGT AND TUESDAY. EXPECT WINDS TO GUST TO SCA LEVELS TNGT AND SEAS TO BUILD TO SCA LEVELS AS WELL. WINDS DROP OFF FOR TUESDAY BUT SEAS WILL REMAIN ROUGH THRU THE DAY. CONDITIONS SHOULD BE DROPPING BELOW SCA LEVELS TUESDAY NGT. LONG TERM...PERSISTENT S-SW FLOW COULD CONTINUE TO PRODUCE SOME SWELL TO NEAR 5 FT WED NIGHT AND THU...BUT OTHERWISE WED THRU SAT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT TUESDAY FOR ANZ150>154. && $$

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