Area Forecast Discussion
Issued by NWS Caribou, ME

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000 FXUS61 KCAR 311418 AFDCAR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 1018 AM EDT FRI JUL 31 2015 .SYNOPSIS... AN UPPER DISTURBANCE WILL CROSS NORTHERN MAINE TODAY FOLLOWED BY A WEAK RIDGE OF HIGH PRESSURE TONIGHT. UNSETTLED CONDITIONS WILL PERSIST SATURDAY AND SUNDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS. && .NEAR TERM /THROUGH TONIGHT/... 1015 AM UPDATE...NO SIGNIFICANT CHANGES WERE NEEDED WITH THIS UPDATE. MAINLY MADE ADJUSTMENTS TO SKY, POPS, AND TEMPS TO MATCH CURRENT SATELLITE/RADAR/SURFACE OBSERVATION TRENDS. ALSO REMOVED FOG WORDING AS MOST OF IT HAS BURNED OFF THIS MORNING. PREVIOUS DISCUSSION...AFTER THE FOG THIS MORNING, THE CHALLENGE WILL BE THE CONVECTIVE POTENTIAL THIS AFTERNOON. THE FRONTAL BOUNDARY HAS MOVED TO THE E W/FOG AND LOW CLOUDS IN ITS WAKE. SOME WEAK SURFACE RIDGING WAS TAKING PLACE PER THE 06Z ANALYSIS ALLOWING FROM PARTIAL CLEARING ABOVE THE LOW CLOUDS AND FOG THAT WAS IN PLACE ATTM. THE CWA SHOULD SEE SUNSHINE AFTER 12Z(8AM)AND THE FOG BURNS OFF. IT WILL REMAIN QUITE HUMID TODAY W/DAYTIME TEMPERATURES PUSHING THROUGH THE 70S AND LOWER 80S FOR THE NORTHERN 1/2 WHILE CENTRAL AND DOWNEAST AREAS SHOULD SEE MID 80S. AN UPPER LEVEL DISTURBANCE W/ITS ASSOCIATED SURFACE TROF WILL MOVE THROUGH THE REGION THIS AFTERNOON. THERE IS ENOUGH MID LEVEL FORCING TO KICK OFF SOME SHOWERS AND W/THE ATMOSPHERE DESTABILIZING. SB CAPES ARE FORECAST TO HIT 800-1200 JOULES W/LIS DROPPING TO -2. SHEAR IS THERE AT THE 0-6KM LAYER(25KTS). THIS WOULD BE ENOUGH TO ALLOW FOR TSTMS TO DEVELOP. THE LACKING FEATURES TO PREVENT ORGANIZED CELLS IS THAT MOISTURE APPEARS TO BE LIMITED TO ABOUT 800MBS AND 850-500MB LAPSE RATES LOOK MARGINAL(6.0C/KM). THEREFORE, DECIDED TO GO W/ISOLATED TSTMS AND CONFINED THIS TO THE NORTHERN AND WESTERN AREAS WHERE BEST INSTABILITY AND FORCING RESIDE. FOR TONIGHT, WEAK HIGH PRES LOOKS TO RIDGE ACROSS THE CWA PROVIDING MAINLY CLEAR SKIES AND COOLER TEMPERATURES. OVERNIGHT LOWS EXPECTED TO BE IN THE UPPER 50S TO AROUND 60. CONCERNED ABOUT SOME SHALLOW FOG, BUT W/A LIGHT WEST WIND FORECAST DECIDED AGAINST IT ATTM. THE DAYCREW CAN ASSESS THIS FURTHER TODAY. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... THIS PERIOD WILL BEGIN WITH A LARGE SCALE UPPER TROF CENTERED ACROSS THE HUDSON BAY REGION. A SERIES OF UPPER LEVEL IMPULSES WILL TRAVERSE NORTHERN MAINE WITHIN THE MEAN FLOW BOTH WEEKEND DAYS, SETTING THE STAGE FOR MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS. THE QUESTION IS WHETHER OR NOT ANY STORMS ON SATURDAY HAVE THE POTENTIAL TO REACH SEVERE LIMITS. THE SHEAR AT 0-6 KM IS THERE AND IS SHOWN TO BE IN THE RANGE OF 35-45 KTS. H5-H7 LAPSE RATES ARE ALSO FAIRLY IMPRESSIVE AROUND 6.5-7.0 C/KM, WITH FREEZING LEVELS EXPECTED TO BE AROUND 10 KFT. LIMITING FACTOR MAY BE AMOUNT OF DRY AIR ALOFT AND MARGINAL INSTABILITY WITH CAPES ONLY AROUND 500-900 J/KG. THAT BEING SAID, IF STORMS DEVELOP THEY COULD TAP IN TO STRONGER WINDS ALOFT, AND WITH AFOREMENTIONED FREEZING LEVELS THINK HAIL WOULD ALSO BE POSSIBLE. CONSIDERING THESE FACTORS, DECISION WAS MADE TO INCLUDE ENHANCED WORDING FOR GUSTY WINDS AND SMALL HAIL ACROSS NORTHERN AND CENTRAL AREAS FOR SATURDAY AFTERNOON. ALSO NOTED THE NEW DAY TWO OUTLOOK FROM SPC THAT HAS MOST OF OUR REGION IN MARGINAL RISK FOR SEVERE. ANY ONGOING SHOWERS AND THUNDERSTORMS SHOULD QUICKLY DIMINISH EARLY SATURDAY EVENING AS THE UPPER IMPULSE MOVES EAST AND WE LOSE THE HEATING. THIS WILL SET THE STAGE FOR PARTLY CLOUDY SKIES LATER SATURDAY NIGHT. SOME PATCHY FOG COULDN`T BE RULED OUT OVERNIGHT WITH LOWS IN THE MID 50S TO NEAR 60 DEGREES. SUNDAY SHOULD SEE ANOTHER ROUND OF MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS. HIGH TEMPERATURES BOTH SATURDAY AND SUNDAY WILL BE IN THE MID 70S NORTH AND UPPER 70S TO NEAR 80 DOWN EAST, ALTHOUGH IT WILL BE A BIT COOLER ON THE COAST. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... THE UNSETTLED WEATHER PATTERN WILL CONTINUE INTO THE LONG TERM. A 500 MB LOW CENTERED NEAR HUDSON BAY AT THE BEGINNING OF THE PERIOD WILL MIGRATE EASTWARD BY THE END OF THE PERIOD. WILL HAVE TO KEEP THE MENTION OF THE CHANCE FOR SHOWERS THROUGH MOST OF THE PERIOD. COULDN`T RULE OUT AN ISOLATED AFTERNOON THUNDERSTORM EITHER BUT WILL NOT MENTION ATTM. TEMPERATURES AT THE START OF THE PERIOD WILL BE NEAR NORMAL AND THEN FALL TO BELOW NORMAL LEVELS BY MID TO LATE WEEK AS COOLER AIR ASSOCIATED WITH THE UPPER TROF SETTLES ACROSS NORTHERN NEW ENGLAND. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... NEAR TERM: MVFR/IFR CONDITIONS IN PLACE ATTM W/SOME FOG AND LOW CLOUDS. CONDITIONS ARE EXPECTED TO IMPROVE TO VFR BY MID MORNING AS DRIER WORKS ACROSS THE TERMINALS. VFR LOOKS TO BE A GOOD BET THROUGH TONIGHT. SHORT TERM: AVIATORS CAN EXPECT THE CHANCE FOR SHOWERS AND THUNDERSTORMS BOTH SATURDAY AND SUNDAY. ALTHOUGH WE ARE EXPECTING VFR TO PREVAIL MOST OF THE DAYTIME HOURS, THERE COULD BE PERIODS OF MVFR IN ANY HEAVIER SHOWERS OR THUNDERSTORMS. MAINLY VFR CONDITIONS EXPECTED MONDAY AND TUESDAY IN SCATTERED AFTERNOON SHOWERS. && .MARINE... NEAR TERM: FOG COULD HAMPER NAVIGATION THIS MORNING. DRIER AIR WORKING ACROSS THE WATERS WILL ALLOW FOR VSBYS TO IMPROVE. WINDS WILL INCREASE OUT OF THE SW 10 TO 15 KTS. EXPECT SEAS TO RUN 3 TO 4 FT AWAY FROM THE INTRA-COASTAL ZONE. SHORT TERM: WIND/SEAS SHOULD GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE PERIOD. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ NEAR TERM...HASTINGS/HEWITT SHORT TERM...DUDA LONG TERM...DUDA AVIATION...HASTINGS/HEWITT/DUDA MARINE...HASTINGS/HEWITT/DUDA

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