Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 161629 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1229 PM EDT THU OCT 16 2014 .SYNOPSIS... A COLD FRONT WILL SLOWLY APPROACH FROM THE WEST TODAY AND WILL FINALLY CROSS THE REGION LATE TONIGHT. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ON FRIDAY. A SECONDARY COLD FRONT WILL APPROACH FROM THE WEST FRIDAY NIGHT AND SATURDAY AND WILL CROSS THE REGION SATURDAY NIGHT. HIGH PRESSURE WILL GRADUALLY BUILD IN FROM THE WEST SUNDAY THROUGH MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1230 PM UPDATE...HAVE ISSUED A FLASH FLOOD WATCH FOR AREAS OF NH AND ME THAT WILL LIKELY BE MOST IMPACTED BY UPSLOPE-ENHANCED RAINFALL THIS AFTERNOON AND TONIGHT. LOCALIZED 3-4 INCH TOTALS POSSIBLE AND COULD LEAD TO LOCALIZED FLASH FLOODING. MAY ADD THE REST OF THE AREA LATER...BUT MAINLY EXPECTING MORE NUISANCE URBAN FLOODING IN THOSE AREAS OUTSIDE THE WATCH AREA. 10 AM UPDATE...LITTLE CHANGE TO THE GOING FORECAST AT THIS TIME. BANDS OF RAIN...HEAVY AT TIMES...MAINLY TO OUR WEST AND SOUTHWEST THIS MORNING WILL GRADUALLY PUSH EASTWARD THIS AFTERNOON AND EVENING...LIKELY RESULTING IN MINOR URBAN/POOR-DRAINAGE FLOODING. 615 AM UPDATE...UPDATED TEMPERATURES BASED ON CURRENT OBS AND TRENDS...ARE ON THE LEE SIDE OF THE WHITES MOUNTAINS WERE ABOUT 5 DEGREES WARMER THAN ANY GUIDANCE THIS MORNING WITH FAVORABLE DOWNSLOPE AND ADIABATIC HEATING WHITEFIELD WAS STILL IN THE LOW 70S AS OF 6AM. SHOWERS ARE ON THE INCREASE ACROSS THE AREA WITH A LINE OF SHOWERS RUNNING FROM SOUTH TO NORTH ALONG THE VT AND NH BORDER. THE REST OF THE CWA IS ONLY SEEING ISOLATED LIGHT RAINSHOWERS AND DRIZZLE THIS MORNING. HEAVY RAIN WILL CONTINUE TO PUSH NORTH AND EAST AS WE HEAD THROUGH THE MORNING HOURS WITH THE HEAVIEST RAIN MOVING IN THIS AFTERNOON. PREVIOUS DISCUSSION... LOW CLOUDS WITH FOG AND DRIZZLE WILL PERSIST THIS MORNING WITH ON SHORE FLOW. AS OF 3 AM THE HEAVIEST RAIN SHOWER WERE STILL ACROSS EASTERN NY. THE COLD FRONT WILL START TO PUSH INTO NEW ENGLAND THIS AFTERNOON AND SPREAD THE HEAVY RAINFALL INTO OUR AREA. UPPER TROF GOES NEGATIVELY TILTED AND HELPS PULL IN THE MOISTURE FROM GONZALO. MOIST AIRMASS AND STRONG ISENTROPIC LIFT WITH FAVORABLE UPPER LEVEL DIFFLUENCE WILL SUPPORT HEAVY RAINFALL. TRAINING POTENTIAL WILL BE FAIRLY HIGH WITH STORMS MOVING SOUTH TO NORTH AND ENHANCED CONVECTION DUE TO ADDED LIFT FROM THE TERRAIN IS EXPECTED. FOR THE MOST PART WE SHOULD ESCAPE FLASH FLOODING...HOWEVER POOR DRAINAGE AREAS AND PONDING ON ROADWAYS ALONG WITH MAYBE AN ISOLATED FLASH FLOOD EVENT IN HIGH RUNOFF POTENTIAL AREAS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... REALLY...VERY LITTLE CHANGE TO THE FORECAST AS MODELS HAVE REMAINED CONSISTENT OVER THE PAST FEW RUNS. HEAVY RAIN IS EXPECTED THURSDAY NIGHT ACROSS MUCH OF THE AREA. TROPICAL MOISTURE WILL BE PUMPED INTO THE REGION WITH MODERATE TO STRONG SOUTHEAST FLOW AT 850 MB. CURRENTLY LOOKING AT WIDESPREAD 1 TO 2 INCHES OF RAINFALL WITH HIGHER AMOUNTS IN FAVORABLE UPSLOPING LOCATIONS OF THE WHITES AND WESTERN MOUNTAINS OF MAINE. THERE WILL ALSO BE SOME MARGINAL INSTABILITY WHICH COULD KICK OFF AN ISOLATED EMBEDDED THUNDERSTORM. LOOK FOR THE PRECIP TO START WINDING DOWN FROM WEST TO EAST FRIDAY MORNING WITH SOME BREAKS OF SUN BY THE AFTERNOON. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH THE TIMING OF A PASSAGE OF A STRONG COLD FRONT ACROSS MAINE AND NEW HAMPSHIRE SATURDAY EVENING. THIS WILL BRING IN SIGNIFICANTLY COOLER AIR FOR SUNDAY WITH HIGH TEMPERATURES ONLY REACHING THE 40S IN THE MOUNTAINS. THE NEXT INTERESTING FEATURE WILL BE YET ANOTHER CUTOFF LOW PRESSURE SYSTEM DURING THE MIDWEEK PERIOD NEXT WEEK. MODELS CONTINUE TO SUGGEST AN AREA OF LOW PRESSURE WILL DEVELOP OFF THE NEW ENGLAND COASTLINE. MODELS DO DIVERGE WITHIN THE 00Z SUITE HOWEVER AS TO THE STRENGTH OF THIS SYSTEM AND WHETHER IT WILL RETROGRADE BACK TOWARDS THE NEW ENGLAND COAST. THIS WILL NEED TO BE MONITORED IN FUTURE RUNS FOR THE POTENTIAL OF SOME COASTAL FLOODING NEXT WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... SHORT TERM...MAINLY LIFR TO IFR CONDITIONS ACROSS THE AREA THROUGH FRIDAY MORNING UNTIL COLD FRONT CLEARS THE AREA. POSSIBLE LOW LEVEL WIND SHEAR CONDITIONS MAY EXIST OUT AHEAD OF THE COLD FRONT THURSDAY NIGHT. LONG TERM...MAINLY VFR CONDITIONS THROUGH MONDAY. && .MARINE... SHORT TERM...SCA THROUGH FRIDAY AS WINDS WILL GUSTS UP TO 30 KNOTS OUT AHEAD OF COLD FRONT LATE THURSDAY INTO FRIDAY. ALSO...SWELLS UP TO 8 FEET ARE EXPECTED DUE TO THE LONG SOUTHERLY FETCH. LONG TERM...SCA CONDITIONS LIKELY SATURDAY NIGHT INTO MONDAY. && .HYDROLOGY... EXPECTING A 1.5 TO 2.5 INCH RAINFALL EVENT STARTING TODAY AND CONTINUING INTO TONIGHT WITH POSSIBLY UP TO 3" IN FAVORABLE UPSLOPE LOCATIONS. WITH FLASH FLOOD GUIDANCE AT 3 - 3.5 INCHES...NO FLASH FLOOD WATCH WILL BE ISSUED AT THIS TIME. HOWEVER...URBAN AND LOW LYING FLOODING IS POSSIBLE. SOME FLASHIER STREAMS MAY SHOW VERY SHARP RISES AND NOT RULING OUT AN ISOLATED FLASH FLOOD IN AREAS OF STRONGEST CONVECTION. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...FLASH FLOOD WATCH FROM 6 PM EDT THIS EVENING THROUGH LATE TONIGHT FOR MEZ007>009-012>014. NH...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NHZ002>007. MARINE...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM EDT FRIDAY FOR ANZ150>154.
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&& $$ NEAR TERM...EKSTER

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