Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 170726 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 326 AM EDT MON JUN 17 2013 .SYNOPSIS...
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SEVERAL WEAK LOW PRESSURE SYSTEMS WILL CROSS NORTHERN NEW ENGLAND TODAY AND TUESDAY...BRINGING A THREAT FOR SHOWERS OR THUNDERSTORMS. A COLD FRONT WILL CROSS THE REGION TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FOR WEDNESDAY AND THURSDAY. A WARM FRONT CROSSES THE AREA ON FRIDAY...WITH ANOTHER CHANCE FOR SHOWERS. WARMER AND MORE HUMID AIR IS EXPECTED FOR THE WEEKEND.
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&& .NEAR TERM /TODAY/...
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SHORTWAVE TROUGH MOVING THROUGH SOUTHERN QUEBEC THIS MORNING WILL BRING SHOWERS AND AN ISOLATED THUNDERSTORM PRIMARILY NORTH OF THE BORDER EARLY THIS MORNING. BUT AN ISOLATED SHOWER IS POSSIBLE IN NORTHERN LOCATIONS BEFORE 10 AM. ANOTHER SHORTWAVE TROUGH MOVING THROUGH THE CENTRAL GREAT LAKES EARLY THIS MORNING WILL MOVE QUICKLY EAST AND INTO NORTHERN NEW ENGLAND THIS AFTERNOON. THIS... COMBINED WITH INCREASING LOW LEVEL MOISTURE... WILL SET THE STAGE FOR SHOWERS AND SOME THUNDERSTORMS THIS AFTERNOON. OVERALL CAPE VALUES OF 400 TO 800 ARE EXPECTED BY EARLY AFTERNOON... WITH THE ATMOSPHERE BECOMING UNCAPPED BY AROUND NOON. ANY AREAS WHICH CAN HOLD OFF ON DEVELOPING CONVECTION UNTIL LATER IN THE DAY COULD POTENTIALLY TAP INTO BETTER INSTABILITY. THE BETTER SYNOPTIC SCALE LIFT WITH THE SHORTWAVE TROUGH WILL ARRIVE AROUND MID AFTERNOON AND WILL TRIGGER MORE WIDESPREAD PRECIPITATION AND POSSIBLY A LINE OF THUNDERSTORMS. WIND PROFILES TODAY SHOW MODERATE TO STRONG UNIDIRECTIONAL SPEED SHEAR WHICH SUGGESTS THAT THUNDERSTORMS COULD GAIN BETTER ORGANIZATION INTO LINES OR SUPERCELLS. HOWEVER... THE LIMITING FACTOR WILL BE INSTABILITY. AS A RESULT... DO NOT EXPECT A SIGNIFICANT THREAT FOR SEVERE WEATHER TODAY... THOUGH A FEW STRONG STORMS WITH GUSTY WINDS OR SMALL HAIL ARE POSSIBLE... ESPECIALLY IF THUNDERSTORMS GET ORGANIZED INTO LINES OR CLUSTERS OR IF CONVECTION IS SUPPRESSED UNTIL LATER IN THE DAY LEADING TO GREATER INSTABILITY. THE GREATEST THREAT AREA WOULD PROBABLY BE SOUTHERN NEW HAMPSHIRE. TEMPERATURES TODAY WILL TOP OUT IN THE 70S TO LOW 80S. MAV FORECAST HIGH OF 86 IN CONCORD SEEMED A BIT TOO HIGH... BUT IF SHOWERS AND STORMS DO HOLD OFF UNTIL LATER IN THE DAY THEN MID 80S ARE POSSIBLE IN THIS AREA.
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&& .SHORT TERM /TONIGHT AND TUESDAY/...
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EXPECT AREA OF SHOWERS AND STORMS TO MOVE EAST AND WEAKEN BY THE EARLY EVENING HOURS. SURFACE COLD FRONT WILL SAG SOUTH INTO CENTRAL NEW HAMPSHIRE AND SOUTHWEST MAINE BY TUESDAY MORNING. DRIER CONDITIONS WILL BE MOVING IN BEHIND IT TO THE NORTH... BUT THE HUMID AIR MASS WILL REMAIN IN PLACE TO THE SOUTH OF THE BOUNDARY. THIS COULD SET THE STAGE FOR MORE SHOWERS AND THUNDERSTORMS ON TUESDAY ALONG AND SOUTH OF THE FRONT.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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STRONG RIDGE AT 500 MB WILL HOLD IN PLACE OVER THE SOUTH CENTRAL UNITED STATES THROUGH THE WEEKEND. INITIALLY...WEAKLY AMPLIFIED TROUGHING WILL HOLD TO OUR NORTH...WITH NORTHWEST FLOW OVERHEAD. SO...AFTER THE COLD FRONTAL PASSAGE TUESDAY NIGHT...LOOK FOR SEASONABLE TEMPERATURES...MAXES IN THE 70S...MINS IN THE 40S AND 50S...WITH GENERALLY DRY AIR...FOR WEDNESDAY INTO THURSDAY. THE TROUGH LIFTS NORTHEAST BY LATE IN THE WEEK ALLOWING THE RIDGING ALOFT TO SHIFT EAST. COULD SEE SOME SHOWERS/THUNDERSTORMS ON FRIDAY AS A WARM FRONT WORKS THROUGH. WARMER AND MORE HUMID AIR WORKS IN FOR THE WEEKEND. MODELS BEGIN TO DISAGREE AS TO HOW QUICKLY AND HOW FAR SOUTH THE UPPER TROUGH DEVELOPS OVER THE NORTHERN PLAINS AND GREAT LAKES...BUT ULTIMATELY THIS COULD PRODUCE SOME PRECIPITATION/CONVECTION SUNDAY OR MONDAY.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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SHORT TERM...VFR CONDITIONS EXPECTED TO START THE DAY... BUT SHOWERS AND THUNDERSTORMS WILL QUICKLY FORM BY 16-20Z. CONFIDENCE IN THUNDERSTORMS AT EACH TERMINAL IS NOT HIGH ENOUGH TO MENTION IN MOST TAFS ESPECIALLY CLOSER TO THE COAST. SHOWERS AND STORMS MOVE EAST THIS EVENING WITH A COLD FRONT DROPPING SOUTH INTO THE AREA. COULD SEE MORE SHOWERS AND A FEW STORMS ON TUESDAY IN SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE. LONG TERM...SOME FLIGHT RESTRICTIONS COULD BE POSSIBLE TUESDAY NIGHT IN LOW CLOUDS/FOG...AS LINGERING LOW LEVEL MOISTURE HANGS ON BEHIND A COLD FRONT. OTHERWISE...MAINLY VFR WEDNESDAY THRU FRIDAY.
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&& .MARINE...
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SHORT TERM...A LIGHT SOUTH TO SOUTHWEST FLOW IS EXPECTED OVER THE WATERS TODAY AND TUESDAY. A COLD FRONT CROSSES THE WATERS TUESDAY NIGHT. LONG TERM...NO FLAGS ANTICIPATED WEDNESDAY THRU FRIDAY...ALTHOUGH LOW PRESSURE WELL TO THE SOUTH COULD INCREASE SWELL LATE IN THE WEEK.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ SYNOPSIS...CEMPA NEAR TERM...KIMBLE SHORT TERM...KIMBLE LONG TERM...CEMPA AVIATION...CEMPA/KIMBLE MARINE...CEMPA/KIMBLE

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