Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 272315 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 715 PM EDT MON JUL 27 2015 .SYNOPSIS... WARM AND HUMID AIR WILL REMAIN OVER MAINE AND NEW HAMPSHIRE FOR THE NEXT SEVERAL DAYS. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MAINLY DURING THE AFTERNOON AND EVENING HOURS. SOME STRONGER STORMS ARE POSSIBLE ON TUESDAY. A COLD FRONT WILL CROSS THE REGION ON THURSDAY. A WEAK DISTURBANCE MAY BRING A FEW SHOWERS TO THE MOUNTAINS FRIDAY. UPPER LEVEL TROUGHING REMAINS IN PLACE THROUGH EARLY NEXT WEEK BRINGING PERIODIC FRONTAL PASSAGES AND UNSETTLED WEATHER. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 705 PM UPDATE: INPUT LATEST OBS DATA AND NEEDED JUST MINOR TWEAKS TO TEMPERATURES. SCATTERED THUNDERSTORMS CONTINUE ACROSS THE WESTERN MOUNTAINS OF MAINE AT THIS TIME. DREADED NORTHWEST FLOW ALOFT COMBINED WITH JUICED UP ATMOSPHERE MEANS MORE CONVECTION AHEAD LATE TONIGHT AS SOME MODELS INDICATING. TRENDS OF WATER VAPOR IMAGERY SHOW MORE THUNDERSTORMS TO ARRIVE LATE TONIGHT AS A SHORT WAVES MOVE SOUTHEAST THROUGH UPPER FLOW. MAY NEED TO ADJUST POPS FOR LATER TONIGHT ON THE NEXT UPDATE. PREVIOUS DISCUSSION: CONVECTION IN SOUTHERN NH LATE THIS AFTERNOON SHOULD WANE BEFORE SUNSET...BUT SEVERAL CLUSTERS OF CONVECTION WILL MOVE INTO NORTHERN ZONES AROUND OR SHORTLY AFTER SUNSET...AND THESE SHOULD TRACK EAST TO SOUTHEAST OVERNIGHT INTO EARLY TUESDAY. MOST OF THIS ACTIVITY WILL STAY ROUGHLY N AND E OF OF KRKD-KHIE LINE WITH LITTLE SHRA OR TSRA S OF THERE OVERNIGHT. ONCE AGAIN COASTAL FOG AND STRATUS WILL DEVELOP THIS EVENING AND PERSIST THRU TUE MORNING. OVERNIGHT LOWS WILL BE MILD GENERALLY IN THE LOW 60S N TO MID-UPPER 60S ELSEWHERE. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... ANOTHER WEAK WAVE ALOFT PASSES JUST N OF THE CWA...ALTHOUGH CAPPING INVERSION ALSO WILL BE PRESENT SO THAT WILL LIMIT CONVECTION TO PLACES THAT CAN GENERATE FORCING. HOWEVER...WILL SEE DISTINCT SEA BREEZE BOUNDARY DEVELOP...WHICH WILL ACTUALLY BE SOMEWHAT ENHANCED BY WEAK SFC WINDSHIFT ASSOCIATED WITH THE WAVE...AND THIS AREA WILL LIKELY BE FOCUS FOR CONVECTION. ALSO...STRONG SFC BASED INSTABILITY WITH CAPES OF 1K- 2K...COMBINED WITH AT LEAST GOOD VERTICAL SPEED SHEAR WILL HELP GENERATE GOOD UPDRAFTS AND PULSE STORMS THAT COULD PRODUCE STRONG WINDS. ALSO...LOCALIZED LOW LEVEL CONVERGENCE ALONG THE SEA BREEZE AND FRONTAL BOUNDARY REGION WILL BEING HELICITY VALUES INT EH 100-200 RANGE...SO CHANCE FOR A COUPLE ROTATING UPDRAFTS AS WELL...WILL COULD ADD LARGER HAIL TO THE MIX. MAXES WILL RISE TO NEAR 90 IN SRN NH...AND 80S MOST OTHER PLACES WITH TDS IN THE MID- UPPER 60S. WILL SEE SOME CONVECTION LINGER INTO THE EVENING...BUT SHOULD DIE OFF SHORTLY AFTER SUNSET...WITH SKIES CLEARING AND FOG FORMING AGAIN. COULD SEE MINS A DEGREE OR TWO COOLER THAN MON NIGHT AS SLIGHTLY DRIER AIR WORKS IN BEHIND THE BOUNDARY. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN THROUGH EARLY NEXT WEEK. WE BEGIN THE PERIOD WITH A SHORTWAVE RIDGE TRAVERSING THE AREA WEDNESDAY. IT`LL BE A HOT AND HUMID DAY WITH WIDELY SCATTERED CONVECTION. BY THURSDAY...THE RIDGE SLIDES OFFSHORE WITH NEXT UPSTREAM IMPULSE DRIVING A WEAK COLD FRONT ACROSS THE REGION. THURSDAY WILL BE ANOTHER HOT AND INCREASINGLY HUMID DAY...WITH SCATTERED STRONG CONVECTION DEVELOPING ALONG AND AHEAD OF THE COLD FRONT. BEHIND THIS LEAD IMPULSE...WE CARVE OUT A BROAD UPPER TROUGH FOR THE TAIL END OF THE WEEK AND THROUGH THE FIRST HALF OF NEXT WEEK...THAT WILL FEATURE A SEEMINGLY ENDLESS PROCESSION OF SHORTWAVE IMPULSES AND ASSOCIATED WEAK SURFACE FRONTS OR TROUGHS. FRIDAY FEATURES SOME WEAK RIDGING...AND ONLY A MINIMAL CHANCE OF CONVECTION FOR OUR FAR NORTHERN AND EASTERN ZONES. THE NEXT IMPULSE WILL DRIVE A WEAK COLD FRONT ACROSS THE REGION SATURDAY...WITH CONVECTION TO BE STRONGER AND MORE WIDESPREAD THEN FRIDAY. THE NEXT IMPULSE AND ASSOCIATED WEAK FRONT/SURFACE TROUGH ARRIVES FOR LATE SUNDAY INTO MONDAY WITH THE NEXT ROUND OF CONVECTION. && .AVIATION /23Z MONDAY THROUGH SATURDAY/... SHORT TERM...ANOTHER ROUND OF COASTAL FOG AND STRATUS EXPECTED TONIGHT INTO FRI MORNING...WITH SOME VLY FOG POSSIBLE AS WELL. IMPROVEMENT TO VFR ON TUESDAY...BUT SEVERE STORMS ARE POSSIBLE TUE AFTERNOON. LONG TERM... WED - SAT...SCT MVFR IN SHRA AND TSRA EACH DAY. && .MARINE... SHORT TERM...WEAK PRESSURE GRADIENT KEEPS WIND FLOW LIGHT AND SEAS FAIRLY CALM. LONG TERM... THU PM - FRI AM...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM...MARINE SHORT TERM...MARINE

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