Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 271018 AFDCAR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 618 AM EDT MON JUL 27 2015 .SYNOPSIS... WARMER AND MORE HUMID AIR WILL OVERSPREAD THE REGION TODAY RIGHT INTO TUESDAY. A FRONTAL BOUNDARY WILL DROP ACROSS THE REGION TUESDAY AFTERNOON INTO TUESDAY EVENING WITH THE THREAT FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... UPDATE 0615 EDT: HAVE ADJUSTED TEMPERATURE AND DEW POINT BASED ON LATEST OBSERVATIONS...NO OTHER CHANGES NEEDED. A SURFACE TROUGH WILL MOVE ACROSS THE AREA TODAY. AN UPPER LEVEL LOW PRESSURE SYSTEM WILL APPROACH THE REGION FROM THE NORTH TONIGHT. EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP THIS AFTERNOON... ESPECIALLY ACROSS THE NORTHWEST...WILL INCLUDE ENHANCED WORDING FOR SMALL HAIL. WILL BLEND THE NAM AND GFS FOR POPS... QPF AND SKY COVER. THE BIAS CORRECTED CONSENSUS ALL WAS USED FOR THE MAXIMUM TEMPERATURE AND THE CONSENSUS ALL USED FOR MINIMUM TEMPERATURE BASED ON LATEST VERIFICATION. FOR WINDS HAVE USED THE MOSG25. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... MAIN CHALLENGE THIS TERM WILL BE THE THREAT FOR STRONG TO POSSIBLY SEVERE TSTMS TUESDAY AFTERNOON INTO TUESDAY EVENING. AN UPPER LOW WL BE DROPPING SOUTH FROM THE HUDSON BAY REGION ON TUESDAY WHILE AT THE SURFACE WILL BE A FRONTAL BOUNDARY MOVING ACROSS THE REGION. ATMOSPHERE WILL BECOME UNSTABLE BY MID MORNING W/LLVL INVERSION BREAKING. LOW CLOUDS AND ANY FOG WILL BURN OFF ALLOWING FOR HEATING TO DESTABILIZE THINGS MORE BY LATER IN THE MORNING. SURFACE DEWPOINTS ARE FORECAST TO INCREASE WELL INTO THE 60S BY THE AFTERNOON W/TEMPS HITTING AOA 80F EXCEPT FOR THE IMMEDIATE COAST DUE TO A SSW WIND. LLVL CONVERGENCE ALONG/AHEAD OF THE FRONT AND UPPER LEVEL DYNAMICS WILL ALLOW FOR SHOWERS AND THUNDERSTORMS TO DEVELOP. UPPER LEVEL DIFLUENCE SETS UP IN THE AFTERNOON AS THE UPPER LOW MOVES ACROSS QUEBEC. IN THE LOWER LEVELS, SB/MU CAPES FORECAST TO BE 1500-2000 JOULES BY THE AFTERNOON W/LIS -4 TO -6. TOTALS HITTING AROUND 50 W/THE SHOWALTER INDEX DROP BELOW 0 IN SOME AREAS. 850-500MB LAPSE RATES EXPECTED TO BE AROUND 6.5 C/KM W/PWATS AROUND 1.2 INCHES. PLUS, FREEZING LEVELS/WBZS ARE FORECAST TO AROUND 11K FT WHICH IS RIGHT IN THE REGION FOR HAIL POTENTIAL. THE NAM AND GFS SOUNDING DO SHOW SOME DRIER AIR ALOFT ESPECIALLY ABOVE 700MB. THIS WOULD LEAD TO HAIL AND EVEN STRONG WIND GUST POTENTIAL. AFTER FURTHER COLLABORATION W/GYX, DECIDED TO ADD HAIL AND GUSTY WINDS IN THE FORECAST GRIDS W/THE EXCEPTION OF THE COAST ATTM DUE TO SSW WIND. SPC HAS PLACED THE REGION IN A MARGINAL RISK FOR SOME STORMS TO BECOME SEVERE W/HAIL AND STRONG WIND GUSTS THE MAIN THREATS. ATTM, STORM STRUCTURE LOOKS TO BE MULTICELLULAR W/A STORM OR 2 GOING SUPERCELL. ONE THING TO NOTE, THIS SETUP MATCHES THE MINI-SUPERCELL PATTERN W/UPPER LOW TO THE NW AND COLD POOL ALOFT. THE FRONTAL BOUNDARY IS EXPECTED TO MOVE THE E TUESDAY NIGHT W/SHOWERS AND TSTMS WINDING DOWN. GIVEN THE GUIDANCE SHOWING SOME INSTABILITY LINGERING, DECIDED TO KEEP THE MENTION OF TSTMS IN THE FORECAST THROUGH MIDNIGHT AND THEN JUST SHOWERS. DRIER WEATHER FOR WEDNESDAY W/HIGH PRES MOVING ACROSS THE REGION W/SLIGHTLY COOLER TEMPERATURES AS WELL MENTIONED BY THE DAYCREW W/SEASONAL NORMS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... A WSW FLOW IN THE UPPER LEVELS WILL ALLOW FOR AN UNSETTLED/ACTIVE WEATHER PATTERN INTO THE WEEKEND W/DISTURBANCES SWINGING ACROSS THE REGION. THIS WILL LEAD TO SHOWERS AND TSTMS ON AND OFF THROUGH THE PERIOD. THE DAYS THAT LOOK TO HAVE THE MOST NOTICEABLE THREAT FOR SHOWERS AND TSTMS WILL BE ON THURSDAY AND SATURDAY AS FRONTAL SYSTEMS SWING THROUGH THE REGION. THE AIRMASS ON THURSDAY WILL BECOME INCREASINGLY HUMID AND RATHER WARM. INSTABILITY WILL BE THERE FOR TSTM DEVELOPMENT RIGHT INTO THURSDAY NIGHT. SOME OF THE PARAMETERS POINT TO POTENTIAL FOR SOME STRONGER TSTMS THURSDAY AFTERNOON INTO THE EVENING, BUT SINCE THIS IS DAY 4, DECIDED TO STAY W/GENERAL WORDING ATTM. THIS CAN BE ADDRESSED AS WE MOVE IN CLOSER. THE FRONT IS EXPECTED TO CLEAR THE REGION BY LATER THURSDAY NIGHT W/SHOWERS AND TSTMS WINDING DOWN. A SURFACE TROF COMBINED W/AN UPPER LEVEL DISTURBANCE COULD ALLOW FOR SOME SHOWERS AND PERHAPS A TSTM TO KICK OFF BY LATER FRIDAY MORNING INTO THE AFTERNOON. ATTM, AREAL COVERAGE IS EXPECTED TO BE LESS THAN 50%, SO STAYED W/CHANCE POPS(30-40%). PARTIAL CLEARING FRIDAY NIGHT BUT ANOTHER FRONTAL BOUNDARY IS SHOWN BY THE LONG RANGE GUIDANCE TO SWING ACROSS THE REGION ON SATURDAY W/MORE SHOWERS AND PERHAPS TSTMS. TEMPERATURES DURING THE TIMEFRAME ARE EXPECTED TO BE AT THE NORMAL RANGE. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... NEAR TERM: EXPECT IFR/MVFR CONDITIONS THROUGH TONIGHT. SHORT TERM: MVFR/IFR TUESDAY MORNING, BUT EXPECTING VFR AS THE LOW CLOUDS AND ANY FOG BURN OFF. EXPECTING POSSIBLE MVFR BY TUESDAY AFTERNOON INTO THE EVENING W/SHRA AND TSRAS. SOME TSRAS COULD CONTAIN HAIL AND GUSTY WINDS. POSSIBLE FOG W/CONDITIONS DIPPING TO IFR LATER TUESDAY NIGHT INTO EARLY WEDNESDAY. MORE SHRAS AND TSRAS POSSIBLE FOR THURSDAY W/CONDITIONS DOWN TO MVFR AND PERHAPS IFR FOR ALL TERMINALS. && .MARINE... NEAR TERM: HAVE USED THE NAM12 FOR SUSTAINED WINDS. FOR WAVES: WITH LIGHT LOCAL WINDS COMBINED SEAS CURRENTLY MADE UP OF BLEND TWO WAVES SYSTEMS COMING INTO WATERS. PRIMARY WAVE GROUP SOUTHERLY AROUND 2-3 FEET/6 SECONDS AND SECONDARY GROUP SOUTHEASTERLY 1-2 FEET 11 SECONDS. WILL USE THE NEAR SHORE WAVE MODEL TO POPULATE WAVE GRIDS. SHORT TERM: WINDS/SEAS WILL REMAIN BELOW SMALL CRAFT LEVELS THROUGH THE TERM. VISIBILITIES WILL BE REDUCED IN AREAS OF FOG TUE MORNING. SHOWERS AND POSSIBLE TSTMS TUESDAY AFTERNOON INTO TUESDAY WILL KICK SEAS A BIT AND LEAD TO GUSTY WINDS ESPECIALLY IN THE INTRA COASTAL ZONE. A BREAK ON WEDNESDAY W/DRIER WEATHER AND LIGHT WINDS W/HIGH PRES MOVING OVER THE WATERS. THIS WILL BE SHORT LIVED HOWEVER AS ANOTHER FRONTAL BOUNDARY IS EXPECTED FOR THURSDAY INTO EARLY FRIDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...MIGNONE SHORT TERM...HEWITT LONG TERM...HEWITT AVIATION...MIGNONE/HEWITT MARINE...MIGNONE/HEWITT

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