Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 292328 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 728 PM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE WILL RETURN TODAY AND MOVE OFF THE COAST OVER THE WEEKEND ALLOWING A WARM AND HUMID SOUTHWEST FLOW TO RETURN. ANOTHER COLD FRONT CROSSES THE REGION SUNDAY MORNING. COOL...CANADIAN HIGH PRESSURE WILL BUILD BACK OVER THE REGION EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 720 PM UPDATE: OCEAN STRATUS/FOG HAS SPREAD FURTHER INLAND TO THE ADJACENT COASTAL AREAS AT THIS TIME. MINOR ADJUSTMENT FOR PLACEMENT OF LOW CLOUDS AND FOG FURTHER INLAND. ALSO MINOR TWEAKS TO TEMPS BASED ON LATEST OBS. PREVIOUS DISCUSSION: MAIN FORECAST PROBLEM WILL BE MARINE STRATUS QUICKLY APPROACHING THE COAST. HI-RES MODEL GUIDANCE ACTUALLY HAS A VERY GOOD HANDLE ON THE CURRENT DEPICTION BASED ON VISIBLE SATELLITE. LEANING HEAVILY ON THE NARRE AND HRRR FOR TIMING AND COVERAGE FOR THE OVERNIGHT PERIOD. COASTAL ME...ESPECIALLY NEAR KPWM WILL SEE STRATUS SOONEST...WITH ALL COASTAL AREAS LIKELY SEEING LOW CIGS BY 00Z. THRU THE NIGHT THIS WILL CREEP INLAND...AND SHOULD ROUGHLY MATCH THE CURRENT SEA BREEZE FRONT OUTLINE. WINDS SHIFTING TO SWLY WILL KEEP STRATUS CONFINED TO MAINLY THE GREAT BAY AREA AND E IN SERN NH...WHILE ALLOWING IT TO PUSH AS FAR INLAND AS KAUG AND KWVL IN CENTRAL ME. WHILE CONFIDENCE IS HIGH IN LOW CLOUDS...CONFIDENCE IS SOMEWHAT LOWER IN FOG AND DRIZZLE. THERE ARE SOME SIGNS BASED ON FORECAST SOUNDINGS THAT THIS COULD DEVELOP OVERNIGHT. HRRR IS AGGRESSIVE ON VSBYS BELOW 1/2 SM...WHILE NARRE IS A LITTLE MORE UP IN THE AIR. SREF VSBYS PROBABILITIES OF GREATER THAN 80 PERCENT FOR LESS THAN 1 SM VSBY POINT TOWARDS SOME FOG MORE LIKELY THAT NOT. SO WILL HAVE AREAS OF FOG IN THE GRIDS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... GUSTY SW FLOW DEVELOPS AHEAD OF A SLOWLY APPROACHING COLD FRONT SAT. THERE IS SUFFICIENT SHEAR FOR ORGANIZED STORMS ALONG THE FRONT...BUT IT WILL DELAY IN REACHING THE FORECAST AREA. SREF CALIBRATED SEVERE TSTM PROBABILITIES PEAK AROUND 21Z ACROSS THE FAR NRN ZONES. ENVIRONMENT LOOKS FAIR ACROSS THIS AREA...SO WILL ADD GUSTY WINDS TO THESE ZONES...AND DELAY TSTMS FOR COAST UNTIL OVERNIGHT. THE OTHER THREAT TO WATCH WILL BE FLASH FLOODING. PWAT VALUES WILL BE RUNNING HIGHER THAN NORMAL...AND SLOW FRONTAL MOVEMENT COUPLED WITH TRAINING STORMS COULD YIELD SOME WATER ISSUES. LOSS OF DAYTIME HEATING SHOULD HELP ANY STORMS TO WEAKEN AND BECOME MORE SCATTERED...BUT A RENEWAL OF DEVELOPMENT IS POSSIBLE EARLY SUN AS THE DAY HEATS UP AGAIN. && .LONG TERM /SUNDAY THROUGH FRIDAY/... POSITIVELY TILTED SHORTWAVE TROUGH PUSHES THE COLD FRONT THE REMAINDER OF THE WAY OFFSHORE SUNDAY MORNING WITH SHOWERS COMING TO AN END IN THE EARLY AFTERNOON. DENSE HIGH PRESSURE TO OUR NORTH MAKES LITTLE HEADWAY SOUTH HOWEVER AS ANOTHER WAVE OF LOW PRESSURE MOVES ALONG THE OFFSHORE FRONT. LINGERING CLOUDS AND COOLER CANADIAN AIR MOVING IN WILL KEEP THE MOUNTAINS COOL (MID 50S) WHILE MUCH OF THE COASTAL PLAIN CLEARS OUT AND WARMS INTO THE UPPER 60S ON SUNDAY. MONDAY AND TUESDAY WILL GENERALLY WARM INTO THE 60S. THE PROXIMITY OF OFFSHORE FRONTAL SYSTEM AS WELL AS A STEADY STREAM OF SHORT WAVE ENERGY WILL KEEP A CHANCE OF SHOWERS OVER SOUTHERN AND COASTAL SECTIONS OF NH AND MAINE THROUGH MONDAY. THERE IS LITTLE INSTABILITY TO BE HAD BUT THERE MAY BE SOME LIGHTNING OFFSHORE. FOLLOWING THIS A STOUT CUTOFF SHORT WAVE MOVES TOWARDS THE AREA TUESDAY INTO WEDNESDAY MORNING ON NEARLY ZONAL FLOW INCREASING RAIN CHANCES ACROSS THE ENTIRE AREA. HIGH PRESSURE BUILDS IN BEHIND THIS SYSTEM BRINGING DRY AND WARM CONDITIONS THURSDAY AND FRIDAY. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...WIDESPREAD IFR/LIFR IS EXPECTED TONIGHT FOR COASTAL TERMINALS AS MARINE STRATUS INVADES THE AREA. BETWEEN 21 AND 00Z MOST SITES SHOULD BE IFR OR LOWER. KAUG MAY TAKE A COUPLE EXTRA HOURS FOR LOW CIGS TO WORK INLAND...BUT BY 03Z IFR IS EXPECTED. LOW CIGS PERSIST INTO SAT MORNING BEFORE LIFTING. GUSTY SW WINDS AROUND 20 KTS POSSIBLE SAT AFTERNOON. TSTMS ARE POSSIBLE LATE SAT INTO SUN FOR ALL TERMINALS. HIGHEST CONFIDENCE FOR TSTMS IS FOR KHIE SAT EVENING. LONG TERM...IMPROVING CONDITIONS SUNDAY WITH PERIODS OF MVFR IN SHOWERS ALONG THE COAST CONTINUING THROUGH WEDNESDAY. && .MARINE... SHORT TERM...SW RETURN FLOW WILL INCREASE SAT. COOL WATERS SHOULD LIMIT THE AMOUNT OF MIXING OF THE STRONGEST WINDS TO THE SURFACE...BUT SUSTAINED FLOW SHOULD BUILD SEAS ABOVE 5 FT BY LATE SAT. OCCASIONAL GUSTS TO 25 KTS ARE NOT OUT OF THE QUESTION EITHER. LONG TERM...WAVES DROP BELOW SCA CRITERIA SUNDAY MORNING. HIGH SEAS RETURN MONDAY EVENING THROUGH TUESDAY NIGHT AS A TIGHT PRESSURE GRADIENT SETS UP OVER THE WATERS. && .FIRE WEATHER... INCREASING HUMIDITY AND SOUTHWESTERLY BREEZES WILL LEAD TO LATE AFTERNOON SHOWERS AND THUNDERSTORMS SATURDAY AFTERNOON AND NIGHT. WETTING RAINS WILL BE MOST LIKELY IN THE MOUNTAINS SATURDAY EVENING AND OVERNIGHT. THE AREAS NEAR THE COAST WILL BE MORE LIKELY TO SEE WETTING RAINS SUNDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$

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