Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 010529 AAB AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 129 AM EDT SAT AUG 1 2015 .SYNOPSIS... A WEAK COLD FRONT WILL CROSS THE AREA SATURDAY...BRINGING ANOTHER THREAT FOR SHOWERS AND THUNDERSTORMS. BEHIND THIS FRONT WE WILL SEE ANOTHER DROP IN TEMPERATURES AND HUMIDITY. WEAK LOW PRESSURE ALOFT...SITUATED OVER QUEBEC...WILL BRING A THREAT FOR SHOWERS OR STORMS MONDAY AND TUESDAY. COOLER AIR AND UNSETTLED CONDITIONS MOVE IN FOR THE MIDDLE TO END OF NEXT WEEK. BY LATE IN THE WEEK...LOW PRESSURE MAY FORM ALONG THE MID ATLANTIC SEABOARD...BRINGING MORE RAIN TO OUR REGION. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 125AM UPDATE: UPDATE TO SLOW POPS JUST A TAD...AND HAVE LOWERED TEMPERATURES THAT ARE CURRENTLY NEARING INHERITED OVERNIGHT LOWS BASED ON SLIGHTLY SLOWER ARRIVAL OF MID LEVEL CLOUD COVER. 23Z UPDATE... NOT MUCH TO SPEAK OF THIS EVENING AS DIURNAL CLOUDS QUICKLY DRYING UP AND WINDS ARE DROPPING OFF. RADAR SHOWING CONVECTION AHEAD OF A WEAK COLD FRONT PUSHING IN FROM THE WEST BUT BEST ACTIVITY GENERALLY NORTH OF THE BORDER. SHOWERS AND SOME THUNDERSTORMS PUSHING INTO NORTHERN AND CENTRAL NEW YORK BEGINNING TO FIZZLE AS IT HEADS EAST AND OUT RUNS BEST INSTABILITY. CAN`T RULE OUT A STRAY LATE NIGHT SHOWER IN BORDER ZONES IN THE FAR NORTH BUT THE MAJORITY OF THE FORECAST AREA SHOULD SEE A MOSTLY CLEAR AND DRY NIGHT. TEMPS CURRENTLY RUNNING ABOVE FORECAST AND HAVE TWEAKED THOSE BASED ON CURRENT OBS. NO OTHER CHANGES PLANNED ATTM. PREVIOUS DISCUSSION... AT 18Z...A WEAK SURFACE TROUGH WAS EXITING THE COAST...WITH A SURFACE COLD FRONT SITUATED OVER THE GREAT LAKES. GOES WATER VAPOR SHOWED AN UPPER LOW CENTERED OVER HUDSON BAY. ANOTHER WARM DAY ACROSS THE AREA...BUT NOTICEABLY LESS HUMID AS WESTERLY FLOW INTRODUCED DRIER AIR BEHIND THE FRONT. INSTABILITY CLOUDS WILL MELT AWAY THIS EVENING WITH LOSS OF HEATING. OVER NIGHT...OUTSIDE OF A FEW STRAY CLOUDS FOR THE MOUNTAINS...MOSTLY CLEAR WITH PATCHY LATE NIGHT VALLEY FOG. LOWS WILL RANGE FROM 50S IN THE MOUNTAINS TO LOWER AND MID 60S ELSEWHERE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... ON SATURDAY...A SHORTWAVE IMPULSE PIVOTING AROUND THE UPPER LOW WILL CROSS THE AREA ALONG WITH AN ASSOCIATED COLD FRONT. HIGH TEMPERATURES WILL WARM INTO THE 70S AND 80S. WITH COOLER AIR MOVING IN ALOFT...AND LOWERING FREEZING LEVELS...SOME OF THE STRONGER CELLS MAY PRODUCE HAIL NEAR SEVERE THRESHOLD...ALONG WITH STRONG WIND GUSTS. THE BEST CONVECTIVE COVERAGE WILL BE FAR NORTHERN NEW HAMPSHIRE INTO THE MOUNTAINS AND FOOTHILLS OF MAINE. FOR NOW...I`VE LIMITED ENHANCED WORDING TO GUSTY WINDS AND SMALL HAIL AND CONFINED THE AREA TO FAR NORTHERN AND EASTERN SECTIONS OF THE FORECAST AREA GIVEN SOME CONTINUED UNCERTAINTIES. CONVECTION SHOULD END QUICKLY SATURDAY EVENING WITH LOSS OF HEATING AND AS COLD FRONT CLEARS THE COAST. SOME CLOUDS AND WIDELY SCATTERED SHOWERS COULD LINGER IN THE HIGHER TERRAIN...OTHERWISE A MAINLY CLEAR AND SEASONABLY COOL NIGHT WITH LOWS IN THE LOWER AND MID 50S IN THE MOUNTAINS...AND IN THE 50S TO AROUND 60 ELSEWHERE. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A HIGHLY PERSISTENT PATTERN WILL CONTINUE ACROSS THE CONUS OVER THE NEXT WEEK OR SO. A LARGE UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE WESTERN UNITED STATES WHILE A PERSISTENT CYCLONIC FLOW CONTINUES OVER THE NORTHEAST. A MORE SIGNIFICANT UPPER LEVEL LOW WILL BEGIN TO DIG SOUTHWARD FROM CANADA ON MONDAY. THIS...IN CONJUNCTION WITH A SLOW MOVING COLD FRONT WILL CROSS NEW ENGLAND LATE IN THE DAY AND IN THE EVENING HOURS. EXPECT ISOLATED SEVERE WEATHER WITH THE POTENTIAL FOR LARGE HAIL AND DAMAGING WINDS WHICH WILL CONTINUE INTO MONDAY NIGHT. STRONG CYCLONIC FLOW ALOFT WILL ALLOW FOR MORE SCATTERED SHOWERS ON TUESDAY WITH POSSIBLY A THUNDERSTORM. SIMILAR CONDITIONS WILL OCCUR ON WEDNESDAY...WITH MAINLY DIURNALLY DRIVEN SHOWERS DUE TO STEEP LAPSE RATES ASSOCIATED WITH VERY COLD AIR ALOFT. THE MORNINGS WILL LIKELY BEGIN WITH PLENTY OF SUNSHINE...WITH CLOUDS QUICKLY BUILDING AND THICKENING OVER THE REGION WITH THE DAYTIME HEATING. ON FRIDAY...CYCLOGENESIS WILL LIKELY OCCUR ALONG THE SOUTHERN NEW ENGLAND COASTLINE WITH YET MORE UPPER LEVEL ENERGY DIGGING SOUTH FROM CANADA. THIS SLOW MOVING SYSTEM IN COMBINATION WITH DEEP TROPICAL MOISTURE WILL LIKELY BRING PERIODS OF HEAVY RAINFALL NEXT WEEKEND. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM /THROUGH 06Z SAT/...GENERALLY VFR WITH SOME INCREASING MID LEVEL CLOUDINESS THROUGH DAYBREAK /ESPECIALLY NORTH/...WITH SOME PATCHY GROUND FOG AT HIE BRINGING OCCASIONAL MVFR VSBYS. FOR THE DAY ON SATURDAY...A MID LEVEL DISTURBANCE MOVING INTO THE REGION WILL RESULT IN INCREASING CLOUDS WITH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS NORTHERN NEW HAMPSHIRE AND NORTHWESTERN MAINE DURING THE LATE MORNING HOURS AND CONTINUING THROUGH THE AFTERNOON...WITH MORE ISOLATED ACTIVITY FURTHER SOUTH. THERE WILL LIKELY BE A FEW TEMPORARY PERIODS OF MVFR VSBYS/CIGS... WITH IFR VSBYS POSSIBLE IN A FEW DOWNPOURS...BUT THE DAY WILL REMAIN LARGELY VFR. LEB/HIE/AUG/RKD STAND THE BEST CHANCE OF SEEING STORMS...WHICH COULD BE POTENTIALLY STRONG. ANY CONVECTION WILL QUICKLY WANE DURING THE EVENING WITH PARTIAL CLEARING EXPECTED. WINDS: CALM-LIGHT/VARIABLE WINDS THROUGH DAYBREAK WILL BECOME WEST- SOUTHWESTERLY 10G18KTS FOR THE DAY ON SATURDAY BEFORE BECOMING LIGHT WEST-NORTHWESTERLY /5KTS OR LESS/ SATURDAY EVENING. LONG TERM...MAINLY VFR SAT NIGHT THROUGH TUESDAY... WITH VLY FOG POSSIBLE EACH NIGHT. SCT SHRA/TSRA WILL IMPACT MOST OF THE TERMINALS LATE MON AND MON NIGHT. && .MARINE... SHORT TERM /THROUGH SATURDAY NIGHT/...SOUTHERLY FLOW LATE SAT AND SAT EVENING MAY BRIEFLY APPROACH SMALL CRAFT OUTSIDE THE BAYS AHEAD OF A COLD FRONT...OTHERWISE QUIET WEATHER IS EXPECTED THIS PERIOD. LONG TERM...PERSISTENT SW FLOW SUNDAY AND MONDAY COULD BRING HIGHER SWELLS TO THE COASTLINE SUNDAY NIGHT....WHICH COULD LINGER THROUGH TUESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM...ARNOTT AVIATION...ARNOTT

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