Area Forecast Discussion
Issued by NWS Portland, ME

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KGYX 011905 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 305 PM EDT SAT AUG 1 2015 .SYNOPSIS...
-- Changed Discussion --
A COLD FRONT WILL EXIT THE REGION THIS EVENING AS SCATTERED SHOWERS AND THUNDERSTORMS COME TO AN END. TEMPERATURES AND HUMIDITY DROP OFF A LITTLE MORE BEHIND THIS FRONT. SUNDAY SHOULD BE MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS NEW ENGLAND. WEAK LOW PRESSURE ALOFT...SITUATED OVER QUEBEC...WILL BRING ANOTHER ROUND SHOWERS OR STORMS MONDAY AFTERNOON INTO MONDAY NIGHT.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
SURFACE COLD FRONT AND AN UPPER LEVEL SHORT WAVE WILL BE EXITING TO OUR EAST THIS EVENING. THIS WILL BRING AN END TO ANY REMAINING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. AS SKIES BEGIN TO CLEAR AND WINDS BECOME LIGHT...PATCHY INLAND VALLEY FOG WILL FORM. LOCALLY...THE VISIBILITY MAY DROP DOWN BELOW A MILE IN SOME LOCATIONS.
-- End Changed Discussion --
&& .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
-- Changed Discussion --
EXPECT DRY CONDITIONS SUNDAY MORNING WITH RIDGING OCCURRING ALOFT. HOWEVER...IN THE AFTERNOON...A LARGE SCALE UPPER TROUGH WILL BEGIN TO APPROACH FROM THE NORTHWEST. WITH CYCLONIC FLOW AND COLD AIR ALOFT...DIURNALLY DRIVEN CU WILL FORM - MAINLY OVER NORTHERN AREAS. THERE MAY BE SUFFICIENT MOISTURE FOR A SPRINKLE OR A BRIEF SHOWER...AGAIN...MAINLY CONFINED TO THE FAR NORTH. HOWEVER...HAVE KEPT POPS RELATIVELY LOW FOR THE DAY. A COLD FRONT WILL BEGIN TO APPROACH FROM THE WEST SUNDAY NIGHT. THE CHANCE FOR SHOWERS WILL BE ON THE INCREASE LATE AT NIGHT ALONG THE CANADIAN BORDER. THIS TAKES US TO THE LONG TERM PORTION OF THE DISCUSSION WITH A SLOW MOVING UPPER LEVEL LOW PRESSURE SYSTEM NEAR THE GREAT LAKES REGION.
-- End Changed Discussion --
&& .LONG TERM /MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
WARM MOIST AIR MOVES BACK INTO THE AREA ON MONDAY AHEAD OF AN APPROACHING UPPER LEVEL TROUGH. TEMPERATURES ACROSS THE AREA WARM INTO THE 80S WITH A FEW LOW 90S POSSIBLE IN SOUTHERN NEW HAMPSHIRE. THE INCREASING MOISTURE AT THE SURFACE WILL GENERATE INSTABILITY WHILE THE ADVANCING HEAT ALOFT (700 MB) WILL SERVE AS A CAP TO PREVENT ACCESS TO THAT INSTABILITY UNLESS A FORCING MECHANISM CAN BE FOUND TO OVERCOME THE CAP. AS THE UPPER TROUGH GETS CLOSER TO THE AREA LATER IN THE DAY IT WILL BEGIN ERODING THE CAP AND ALLOW GREATER ACCESS TO THE INSTABILITY IN ADDITION TO PROVIDING UPPER LEVEL LIFT AND PUSHING A SURFACE COLD FRONT EASTWARD. AS A RESULT... EXPECT SHOWERS AND THUNDERSTORMS AS THE TROUGH AND COLD FRONT MOVE THROUGH BUT THIS MAY NOT OCCUR UNTIL LATE IN THE AFTERNOON AND INTO THE OVERNIGHT MONDAY NIGHT. MODELS IN PRETTY GOOD AGREEMENT ON HOLDING PRECIPITATION OFF UNTIL LATE AFTERNOON AT THE EARLIEST. THE NAM IS ACTUALLY THE FASTEST OF ALL THE MODELS IN SPITE OF ITS NORMAL SLOW BIAS... TRIGGERING STORMS AROUND MID AFTERNOON. WITH THE INSTABILITY PRESENT (1000 OR MORE CAPE) ON TUESDAY THERE WILL ALSO BE A SUBSTANTIAL AMOUNT OF WIND SHEAR. MID LEVEL WINDS WILL BE OUT OF THE SOUTHWEST AT ABOUT 45 OR 50 KT WHILE SURFACE WINDS ARE LIGHT OUT OF THE SOUTH. THIS WOULD BE PLENTY SUFFICIENT FOR SUPERCELLS OR A MORE ORGANIZED DAMAGING WIND THREAT. THIS IS IN AGREEMENT WITH THE STORM PREDICTION CENTER`S OUTLOOK FOR MONDAY ALSO. HAVE INCLUDED DAMAGING WINDS WITH THE THUNDERSTORMS ON MONDAY TO HIGHLIGHT THIS THREAT WHICH WILL BE GREATEST OVER NEW HAMPSHIRE AND FAR WESTERN MAINE. UPPER LEVEL TROUGH AXIS AND SURFACE FRONTAL BOUNDARY SHOULD CLEAR THE AREA BY EARLY TUESDAY MORNING... HOWEVER SOME INSTABILITY STILL EXISTS BEHIND IT AND AN ISOLATED SHOWER OR STORM CANNOT BE RULED OUT AS THE PRIMARY UPPER LOW AND TROUGH AXIS MOVE ACROSS THE AREA. COOL HIGH PRESSURE BUILDS IN FROM THE WEST AND NORTHWEST WEDNESDAY THROUGH FRIDAY. EXPECT A LITTLE COOLER TEMPERATURES... ALTHOUGH AN OFFSHORE WIND WILL STILL ALLOW COASTAL AREAS TO GET INTO THE UPPER 70S AND LOW 80S. THE NEXT UPPER TROUGH WILL MOVE THROUGH THE GREAT LAKES ON SATURDAY AND TRIGGER CYCLOGENESIS OFF THE MID ATLANTIC COAST INTO SUNDAY. AN AREA OF RAIN WILL LIKELY FORM AND TRACK THROUGH SOUTHERN NEW ENGLAND AND POSSIBLY INTO SOUTHERN PARTS OF MAINE AND NEW HAMPSHIRE BUT SEEMS MORE LIKELY TO STAY JUST SOUTH OF OUR AREA AT THIS POINT.
-- End Changed Discussion --
&& .AVIATION /19Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
SHORT TERM...ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE NEAR OR OVER THE TAF SITES INTO EARLY THIS EVENING. OTHERWISE CLEARING WITH PATCHY INLAND FOG DEVELOPING. WINDS WILL BE LIGHT. ON SUNDAY...DIURNALLY DRIVEN CU FIELDS WILL DEVELOP DURING THE DAY. ANY SHOWER ACTIVITY SHOULD BE LIGHT AND MAINLY CONFINED TO THE NORTH. MAINLY VFR CONDITIONS. LONG TERM...EARLY MORNING MARINE FOG OR LOW CLOUDS IS POSSIBLE ALONG THE MAINE COASTLINE MONDAY MORNING. SHOULD SEE VFR CONDITIONS AREAWIDE BY LATE MORNING. SHOWERS AND THUNDERSTORMS CROSS THE AREA FROM WEST TO EAST LATE AFTERNOON THROUGH THE OVERNIGHT HOURS. THEN EXPECT VFR CONDITIONS OUTSIDE OF NOCTURNAL FOG IN THE NEW HAMPSHIRE VALLEYS FOR THE REST OF THE WORK WEEK.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
SHORT TERM...EXPECT WAVES AND WINDS TO REMAIN BELOW SMALL CRAFT LEVELS THROUGH SUNDAY. HOWEVER...SEAS WILL BEGIN TO INCREASE LATE SUNDAY NIGHT IN AHEAD OF AN APPROACHING COLD FRONT. LONG TERM...SOUTHERLY FLOW ON MONDAY SHOULD STAY BELOW ADVISORY LEVELS BUT WAVE HEIGHTS COULD EVENTUALLY BUILD TO AROUND 5 FEET ESPECIALLY OVER EASTERN WATERS. A COLD FRONT MOVES WEST TO EAST ACROSS THE GULF OF MAINE ON TUESDAY WITH LIGHTER WINDS BEHIND IT.
-- End Changed Discussion --
&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.