Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 271026 AFDCAR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 626 AM EDT WED MAY 27 2015 .SYNOPSIS... A STRONG SUBTROPICAL RIDGE WILL REMAIN OFF JUST OFF THE EAST COAST THROUGH THE REMAINDER OF THE WEEK. OUTSIDE OF A WEAK COLD FRONTAL PASSAGE LATE THURSDAY...BRINGING SLIGHTLY COOLER AND DRIER AIR THURSDAY NIGHT INTO FRIDAY MORNING...THIS RIDGE WILL BRING A WARM AND HUMID FLOW OF AIR TO OUR REGION THROUGH SATURDAY. A STRONG COLD FRONT WILL LIKELY CROSS THE REGION SATURDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... 625 AM UPDATE...NO SIGNIFICANT CHANGES WERE MADE WITH THIS MORNING`S UPDATE. PREVIOUS DISCUSSION...THE FOCUS FOR TODAY AND TONIGHT IS THE POTENTIAL FOR STRONG TO POSSIBLY SEVERE THUNDERSTORMS. THE LATEST DAY 1 OUTLOOK FROM SPC HAS MUCH OF OUR NORTHERN AND WESTERN AREAS IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS. MAIN THREATS WOULD BE GUSTY WINDS AND HEAVY RAIN. READ ON FOR DETAILS... A NEARLY STATIONARY BOUNDARY WILL REMAIN DRAPED JUST TO THE NORTH OF THE INTERNATIONAL BORDER TODAY AND TONIGHT. THE AIRMASS ON THE SOUTH SIDE OF THIS BOUNDARY IS VERY WARM WITH PLENTY OF MOISTURE; HIGHS WILL REACH INTO THE 80S AWAY FROM THE COAST WHILE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S. MUCH DEPENDS ON HOW MUCH SUN WE CAN GET TODAY, AS THE ATMOSPHERE WILL DESTABILIZE WITH DAYTIME HEATING. SBCAPES ARE PROGGED TO BE IN THE 500-1200 J/KG RANGE FOR MUCH OF OUR REGION, WITH THE HIGHEST VALUES ACROSS THE WEST. A PREFRONTAL TROUGH WILL SLOWLY PUSH INTO THE STATE THIS AFTERNOON AND EVENING, ALLOWING CONVECTION TO FIRE BY EARLY AFTERNOON. MEANWHILE, AN UPPER SHORTWAVE TROUGH WILL EJECT ACROSS THE GREAT LAKES THIS AFTERNOON AND EVENING, INCREASING 0-6 KM SHEAR TO 25-30 KT BY 00Z TONIGHT. WHILE THIS IS MODEST, IT SHOULD BE ENOUGH TO ALLOW FOR SOME ORGANIZED CELLS CAPABLE OF PRODUCING STRONG WINDS. WITH PWATS OF 1.75+ INCHES AND WARM-CLOUD DEPTHS AOA 10 KFT, HEAVY RAIN WILL ALSO BE A DISTINCT POSSIBILITY. WHILE HAIL CAN`T BE TOTALLY RULED OUT, THE HEIGHT OF THE FREEZING LEVEL GREATLY REDUCES ITS CHANCES. THE HIGHEST CHANCE FOR STRONG TO SEVERE STORMS WILL GENERALLY LIE ALONG AND NORTH OF A HOULTON TO DOVER-FOXCROFT LINE. SOUTH OF THIS AREA, SURFACE-BASED INSTABILITY WILL BE LACKING DUE TO SOUTH FLOW OFF THE COLD GULF OF MAINE. SHOWERS AND THUNDERSTORMS WILL WANE THROUGH THE EVENING AS DAYTIME HEATING IS LOST AND INSTABILITY LESSENS. IT`LL BE ANOTHER MUGGY NIGHT AS LOWS WILL STAY IN THE LOWER TO MID 60S AWAY FROM THE COAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... A S/WV MOVG E FROM SRN QB PROV LOOKS LIKE IT WILL PROVIDE A COLD FRONTAL PASSAGE LATER THU AFTN ACROSS THE N TO THU EVE DOWNEAST. THIS TMG WOULD BE FAVORABLE FOR PRE-FRONTAL TSTMS...MSLY OVR NRN/CNTRL PTNS OF THE FA WHERE FCST MAX AFTN SFC BASE CAPES COULD APCH 1000-1500 J/KG WITH UP TO 40 KT OF 0-6KM BULK SHEAR. WE KEPT ENHANCED WORDING FOR HVY RNFL AND GUSTY STRONG WINDS...AND WITH SLIGHTLY LOWER FZLS THUS AFTN/ERLY EVE THAN THIS AFTN...A MENTION OF HAIL. IF TSTMS DID BECOME SVR...THE BIGGEST CONCERN WOULD BE WINDS FROM BOWING LN SEGMENTS...BASED ON THE GREATEST RATIO BEING 0-3KM BULK SHEAR WINDS COMPARED TO THE TOTAL IN THE 0-6KM LAYER. THE SPC OUTLOOK FOR THU AFTN INDICATES MARGINAL ATTM...BUT IT IS POSSIBLE THIS COULD BE RAISED TO SLGT CHC WHEN THIS EVENT GETS CLOSER TO REAL TM. FOLLOWING THE FRONT...CONDITIONS SHOULD IMPROVE QUICKLY BY LATE THU NGT WITH COOLER OVRNGT LOWS ACCOMPANYING LOWER DWPT...THEN FAIR...MSLY SUNNY AND SOMEWHAT DRIER CONDITIONS ON FRI WITH ABV NORMAL HI TEMPS CONT AS THE SFC HI PRES CROSSES THE REGION. WITH THE WARM FRONT MOVG N OF THE ST JOHN RVR FRI NGT...OVRNGT LOW TEMPS WILL BE MILDER UNDER FAIR SKIES AND A SW BREEZE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... SAT LOOKS TO BE A MSLY TO PTLY SUNNY DAY...WARM AND MORE HUMID DAY...SPCLY ACROSS THE N AND IN PARTICULAR...THE NW BROAD RVR VLYS BASED ON THE ORIENTATION OF FCST AFTN MAX 925MB TEMPS XTNDG FROM THE CHAMPLAIN VLY OF NW VT INTO NW ME ON A 200 TO 210 DEG SFC WIND DIRECTION. FOR THIS PD ONLY...WE BLENDED THE 00Z WMODEL HI TEMP GUIDANCE WHICH WAS ONLY GUIDANCE SHOWING THE WARMEST HI TEMPS OF MID TO UPPER 80S OVR NW ME RVR VLYS MATCHING THE FCST ORIENTATION OF THE CORRIDOR OF MAX 925MB TEMPS. WITH SSW WINDS... HI TEMPS OVR DOWNEAST AREAS...SPCLY THE COAST WILL BE COOLER. OTHERWISE...THE 00Z DTMNSTC GFS AND ECMWF SHOW A STRONG COLD FRONT FOR LATE MAY STANDARDS APCHG NW PTNS OF THE FA FROM QB PROV LATE SAT AFTN. ACTUALLY...THIS IS COMPROMISE TMG BETWEEN THE FASTER GFS AND THE 3 TO 6 HR SLOWER ECMWF. DUE TO THE UNCERTAINTY OF THE FRONT ARRIVING ERLY ENOUGH TO UTILIZE MAX HTG AND INSTABILITY DURG THE HEAT OF THE DAY...WE DO NOT MENTION ANY ENHANCED AFTN/EVE TSTM WORDING THIS UPDATE. IN FACT...IF THE 00Z ECMWF SOLUTION PANS OUT...MOST OF THE RNFL WOULD BE STABLE POST FRONTAL SHWRS/ STRATIFORM RNFL AND SPC DOES NOT HAVE ANY XTNDED SVR OUTLOOK FOR THIS SYSTEM ATTM. BEHIND THIS FRONT...MUCH COOLER AND DRIER CONDITIONS WILL SPREAD SWRD INTO THE FA FIRST THRU NRN ME BY ERLY SUN MORN...THEN CONTG TO OFF THE COAST BY MID TO LATE AFTN. AFT MUCH COOLER HI TEMPS SUN AFTN...SPCLY ACROSS THE N...SUN NGT WILL BE A RELATIVELY CHILLY NGT. MON SHOULD BE FAIR...WITH SUNNIEST SKIES ACROSS THE N...WITH THE 00Z ECMWF SHOWING CLDS AND SHWRS LINGERING OVR THE GULF OF ME WITH A FOLLOW-UP S/WV MOVG E OFF THE MID NEW COAST. BOTH MODELS SHOW TUE TO CONT FAIR ATTM WITH SOME REBOUND IN HI TEMPS. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR CONDITIONS ARE EXPECTED TO PREVAIL WITH SOME EXCEPTIONS. PATCHY FOG WILL DROP CONDITIONS TO MVFR WITH OCCASIONAL IFR AT KBHB AND PERHAPS EVEN KBGR FROM 06Z-12Z WEDNESDAY AND AGAIN AFTER 03Z THURSDAY. FROM 12Z WED TO 03Z THU, SHOWERS AND THUNDERSTORMS ARE EXPECTED TO RESULT IN OCCASIONAL MVFR CONDITIONS, ESPECIALLY AT THE NORTHERN TERMINALS. SOME OF THE STRONGER STORMS WILL BE CAPABLE OF PRODUCING HEAVY RAIN AND GUSTY WINDS, ALONG WITH BRIEF PERIODS OF IFR. SHORT TERM: VFR XPCTD ALL TAF SITES XCPT IN TSTMS AND HEAVIER SHWRS THU AFTN AND LATE SAT AFTN INTO SAT NGT AND ANY PATCHY MORN FOG OVR DOWNEAST SITES THU MORN...WHEN MVFR OF IFR CLGS/VSBYS ARE POSSIBLE. && .MARINE... NEAR TERM:THE SMALL CRAFT ADVISORY REMAINS IN EFFECT THROUGH LATE TONIGHT. SOUTH SWELL WILL CONTINUE TO KEEP WAVES AROUND 5 FT, WITH SEAS ACTUALLY BUILDING TO AROUND 6 FT AFTER MIDNIGHT TONIGHT. WINDS WILL BE MARGINAL DUE TO THE COLD OCEAN WATERS, BUT AN OCCASIONAL GUST TO 25 KT CAN`T BE RULED OUT THIS AFTERNOON AND EVENING. SHORT TO LONG TERM: MARGINAL SCA SEAS OVR OUTER MZS WILL LIKELY CONT AT LEAST THRU THU...BUT THIS IS NOT A CERTAINTY...SINCE STABLE SFC-500 M LAPSE RATES COULD REDUCE SFC WINDS ENOUGH TO KEEP WV HTS BLO 5 FT. WV HTS SHOULD DIMINISH THU NGT INTO FRI...BEFORE SLOWLY BUILDING AGAIN FRI NGT INTO SAT TO POSSIBLE SCA WV HTS AGAIN MSLY OVR OUTER MZS. WENT WITH ONLY ABOUT 80 TO 85 PERCENT OF FCST WW3 WV HTS FOR THESE PTNS OF THE FCST DUE TO THE SEASONAL HIGH WIND BIAS OF THE GFS...AND EVEN THESE RESULTANT WV HTS MAY BE GENEROUS. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THURSDAY FOR ANZ050-051. && $$ NEAR TERM...HASTINGS SHORT TERM...VJN LONG TERM...VJN AVIATION...HASTINGS/VJN MARINE...HASTINGS/VJN

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