946  
FXUS61 KGYX 231114 AAA  
AFDGYX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE GRAY ME  
714 AM EDT MON APR 23 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL TAKE CONTROL OF THE REGION TODAY AND BRING US  
A SHORT STRETCH OF VERY NICE WEATHER. SUNNY SKIES THIS AFTERNOON  
WILL ALLOW TEMPERATURES TO CLIMB INTO THE LOWER 60S FOR MUCH OF  
THE AREA. THAT BEING SAID, IT IS SEA BREEZE SEASON SO BEST TO  
KEEP A JACKET HANDY IF YOU ARE GOING TO BE NEAR THE WATER.  
ANOTHER COOL NIGHT IS EXPECTED UNDER CLEAR SKIES AND LIGHT  
WINDS, AS READINGS FALL TO NEAR FREEZING. SOUTHERLY WINDS ON  
TUESDAY WILL BRING IN EVEN WARMER AIR, WITH AFTERNOON HIGHS  
EXPECTED TO CLIMB INTO THE MID TO UPPER 60S. AS WE HEAD INTO  
WEDNESDAY UNSETTLED WEATHER RETURNS WITH THE APPROACH OF OUR  
NEXT STORM SYSTEM. BEYOND THAT, ANOTHER FAST MOVING SYSTEM MAY  
BE IN THE CARDS FOR THE END OF THE WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
UPDATE...MINOR CHANGES TO REFLECT LATEST OBSERVATIONAL TRENDS.  
 
PREVIOUS DISCUSSION...AT THE MOMENT SURFACE RIDGE AXIS IS  
CENTERED OVER THE FORECAST AREA. THAT IS ALLOWING BOTH CLEAR  
SKIES AND NEAR CALM WINDS...AND TEMPS HAVE RESPONDED BY FALLING  
THRU THE 30S IN THE TYPICAL COLD SPOTS. DESPITE THE CHILLY START  
TO THE DAY...FULL SUNSHINE AND A VERY DRY AIR MASS WILL ALLOW  
FOR DEEP MIXING OF THE BOUNDARY LAYER. THE 23.00Z RAOB AT GYX  
SHOWED MIXED LAYER EXTENDING TO ABOUT 800 MB...WELL ABOVE MODEL  
FORECASTS. THAT IS NOT ATYPICAL FOR THIS TIME OF YEAR...AND SO I  
EXPECT MORE OF THE SAME THIS AFTERNOON. IF WE ASSUME MIXING TO  
THAT LEVEL AGAIN TODAY...WE SHOULD SEE WIDESPREAD LOWER 60S. THE  
SWRN ZONES IN NH MAY SEE READINGS A LITTLE WARMER THAN THAT.  
LIGHT PRESSURE GRADIENT WILL ALSO SUPPORT DEVELOPMENT OF SEA  
BREEZES THIS AFTERNOON. SO ALONG THE COAST HIGH TEMPS WILL BE A  
LITTLE EARLIER IN THE DAY...WITH TEMPS FALLING AS COLDER MARINE  
AIR WORKS INLAND. I HAVE BLENDED IN HIGHER RESOLUTION GUIDANCE  
TO SHOW THIS TEMP TREND...AS WELL AS THE QUICK DROP IN READINGS  
BEHIND THE SEA BREEZE FRONT AFTER SUNSET.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
 
 
EXPECT ANOTHER CLEAR AND CHILLY NIGHT UNDER HIGH PRESSURE. AS  
RIDGE AXIS SLIPS EWD THE READINGS MAY NOT BE AS COLD AS WE ARE  
CURRENTLY SEEING OUT THERE...BUT I STILL WENT WELL BELOW MOST  
GUIDANCE. I PREFERRED TO USE THE CURRENT TEMP SPREAD ACROSS THE  
FORECAST AREA AS A STARTING POINT AND BLENDED IN MAV/MET  
GUIDANCE.  
 
RETURN FLOW WILL INCREASE TUE AND ALLOW SOME WARMTH ALOFT TO  
SNEAK NWD INTO THE FORECAST AREA. IF WE CONTINUE THE DEEP MIXING  
OF THE LAST COUPLE OF DAYS AND AS IS EXPECTED TODAY...IT SHOULD  
BE ANOTHER WARM AFTERNOON. MODEL GUIDANCE IS IN AGREEMENT OF AT  
LEAST +5C AT H8...WITH POCKETS OF +7 SHOWING UP ON THE 23.00Z  
GFS. THAT SUGGESTS WIDESPREAD MID 60S AWAY FROM THE COAST...WITH  
SOME LOCATIONS MAKING A RUN AT 70. NEAR THE COAST...ONSHORE FLOW  
WILL LIMIT WARMING SOMEWHAT...ESPECIALLY N OF PWM WHERE SLY FLOW  
WILL KNOCK READINGS DOWN DURING THE AFTERNOON HOURS.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
 
 
FOR THE MOST PART, WE WILL CONTINUE THE SLOW PARADE OF CUT OFF  
LOWS ACROSS THE SOUTHERN PART OF NORTH AMERICA. ONE SUCH LOW,  
CURRENTLY OVER THE MIDSOUTH, WILL MAKE ITS WAY TOWARD THE EAST  
COAST ON WEDNESDAY, WHILE A NORTHERN STREAM TROUGH DIGS IN  
BEHIND IT, KEEPING A COLD FLOW OF AIR OUT OF CANADA INTO THE  
CENTRAL AND EASTERN PARTS OF THE UNITED STATES. THIS TROUGH MAY  
TRY TO CLOSE OFF OVER THE SOUTHEAST USA AS WELL, BUT IT WILL  
GRADUALLY BE PUSHED EASTWARD TOWARD THE EAST COAST THIS WEEKEND  
WHILE RIDGING BUILDS THROUGH THE PLAINS BEHIND IT AND THE NEXT  
SLOW MOVING CUT OFF LOW ARRIVES IN CALIFORNIA. THE GENERAL  
RESULT FOR OUR AREA WILL BE AN INITIAL ROUND OF RAIN CENTERED ON  
WEDNESDAY EVENING AND ANOTHER POSSIBLE IN THE FRIDAY-SATURDAY  
TIME PERIOD, WITH COOL TEMPERATURES EXPECTED FROM MIDWEEK ON.  
 
SLOW-MOVING CUT OFF UPPER LEVEL LOW PRESSURE MAKES ITS WAY  
THROUGH THE SOUTHERN APPALACHIANS TUESDAY NIGHT, WITH SURFACE  
LOW PRESSURE FORMING NEAR THE CAROLINA COAST. TO THE NORTH OF  
THIS LOW, OVER NEW ENGLAND, EXPECT WINDS TO TURN ONSHORE  
SOUTHEASTERLY WITH INCREASING CLOUD COVER. THROUGH THE DAY  
WEDNESDAY EXPECT AN INCREASING CHANCE OF RAIN WITH TEMPERATURES  
QUITE COOL. WENT A FEW DEGREES BELOW GUIDANCE FOR HIGH  
TEMPERATURES ON WEDNESDAY EAST OF THE MOUNTAINS, FORECASTING  
HIGHS GENERALLY IN THE LOW 50S. WITH WATER TEMPERATURES THIS  
TIME OF YEAR IN THE LOW 40S AND AN ONSHORE FLOW EXPECTED, WE MAY  
BE LUCKY TO REACH 50 ON THE COASTAL PLAIN. RAIN BECOMES STEADIER  
FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY WEDNESDAY AND INTO  
WEDNESDAY EVENING, SPREADING ACROSS THE REGION WEDNESDAY NIGHT.  
IT LOOKS LIKE MOSTLY A 0.5 TO 1 INCH RAINFALL FOR THE AREA, BUT  
SOME AREAS MAY GET MORE THAN AN INCH. WITH SOME SNOW LEFT IN THE  
MOUNTAINS, WE SHOULD SEE SOME HIGHER FLOWS ON THE RIVERS WITH A  
POSSIBILITY OF MINOR FLOODING IN THE HEADWATERS.  
 
THE SURFACE LOW PULLS NORTH ON THURSDAY, BUT WE WILL LIKELY SEE  
THE UPPER LOW LINGER OVER OUR AREA WHICH CONTINUES TO CAUSE  
SHOWERY WEATHER, ESPECIALLY DURING THE DAY WHEN DIURNALLY FORCED  
CONVECTION CAN GET GOING. MODELS NOT IN FULL AGREEMENT ON  
WHETHER TO PUSH A FRONT THROUGH AND BRING SOME OFFSHORE WINDS  
FOR THURSDAY OR NOT. IF SO, WE WILL SEE TEMPERATURES A BIT  
WARMER, IN THE UPPER 50S TO MID OVER THE COASTAL PLAIN AND  
SOUTHERN NEW HAMPSHIRE 60S, BUT IF ONSHORE SOUTHERLY FLOW  
CONTINUES, MUCH OF MAINE MAY STAY IN THE LOW TO MID 50S.  
 
FRIDAY IS OUR ONE OFF DAY IN THIS EXTENDED FORECAST. CAUGHT IN  
BETWEEN WAVES, WE SHOULD SEE A PERIOD OF DRIER CONDITIONS WITH  
TEMPERATURES PEAKING IN THE UPPER 50S TO LOW 60S. THE GFS MODEL  
WOULD BE THE ONE TO SPOIL THIS OUTLOOK, THOUGH, AS IT DEVELOPS A  
COASTAL LOW THAT MOVES NORTH TOWARD CAPE COD AND MAY BRING SOME  
RAIN FRIDAY EVENING. ECMWF AND CMC MODELS WASH THIS WAVE OUT AS  
IT MOVES INTO THE ATLANTIC, KEEPING CONDITIONS DRY IN NEW  
ENGLAND WHICH IS THE PREFERRED SOLUTION AT THIS POINT.  
 
LARGE SCALE UPPER TROUGH ARRIVES ON THE EAST COAST ON SATURDAY,  
WITH BOTH THE NORTHERN AND SOUTHERN STREAM TROUGHS ALIGNING.  
STILL UNCLEAR WHICH WAVE WILL BECOME DOMINANT AND IF THE TWO  
TROUGHS WILL FULLY MERGE. SINCE THE GFS DEVELOPS THE STRONGER  
WAVE ON FRIDAY, IT DOES NOT DO MUCH WITH THE MAIN TROUGH AXIS  
MOVING THROUGH ON SATURDAY. MEANWHILE THE ECMWF AND CMC BRING A  
MORE ORGANIZED LOW PRESSURE SYSTEM THROUGH THE REGION... EITHER  
TO THE NORTH OR SOUTH... WITH RAIN ARRIVING. THUS EXPECT  
ANOTHER PERIOD OF RAIN, WITH THE MOST LIKELY TIME PERIOD BEING  
SATURDAY. COOL, SHOWERY WEATHER LIKELY CONTINUES INTO SUNDAY  
WITH THE COLD UPPER TROUGH AXIS OVERHEAD.  
 

 
   
AVIATION /11Z MONDAY THROUGH FRIDAY/
 
 
SHORT TERM...WIDESPREAD VFR EXPECTED UNDER HIGH PRESSURE. LIGHT  
PRESSURE GRADIENT SHOULD ALLOW FOR SEA BREEZES TO FORM AT  
PSM...PWM...AND RKD THIS AFTERNOON. TUE AFTERNOON BACKGROUND  
FLOW BECOMES MORE SOUTHERLY...AND SEA BREEZE MAY EXTEND ALL THE  
WAY TO AUG.  
 
LONG TERM...EXPECT INCREASING CLOUDS AND LOWERING CEILINGS  
TUESDAY NIGHT INTO WEDNESDAY AS AN ONSHORE FLOW DEVELOPS AND  
RAIN MOVES IN FROM SOUTH TO NORTH. SHOULD SEE A PROLONGED PERIOD  
OF IFR CONDITIONS LASTING INTO THURSDAY MORNING, BUT POSSIBLY  
HANGING ON THROUGH THURSDAY AFTERNOON ACROSS MUCH OF MAINE. VFR  
RETURNS THURSDAY NIGHT AND FRIDAY.  
 

 
   
MARINE
 
 
SHORT TERM...WINDS AND SEAS WILL REMAIN BELOW SCA THRESHOLDS  
WITH HIGH PRESSURE IN CONTROL. AFTERNOON SEA BREEZES ARE  
EXPECTED TO FORM THIS AFTERNOON...AND THEN A LITTLE STRONGER TUE  
AFTERNOON AS BACKGROUND FLOW BECOMES MORE SOUTHERLY.  
 
LONG TERM...ONSHORE SOUTHEAST TO EAST FLOW DEVELOPS TUESDAY  
NIGHT AND WEDNESDAY, AND COULD OCCASIONALLY GUST TO 25 KT OR SO  
WITH WAVE HEIGHTS BUILDING INTO THE 5 TO 9 FT RANGE BY  
THURSDAY WHEN THE WIND WILL FINALLY SHIFT TO SOUTHWEST OR  
WESTERLY.  
 

 
   
FIRE WEATHER
 
 
ANOTHER WARM AND VERY DRY DAY IS EXPECTED TODAY. MINIMUM RH  
VALUES ARE EXPECTED TO DROP INTO THE UPPER TEENS. THE GOOD NEWS  
IS THAT WINDS ARE EXPECTED TO BE VERY LIGHT AS WELL...AS RIDGE  
AXIS WILL BE NEARLY OVERHEAD. SEA BREEZES DEVELOPING IN THE  
AFTERNOON MAY ALLOW FOR SOME STRONGER WINDS TO PUSH INLAND  
MAINLY AFTER 2 PM. THIS COULD LOCALLY INCREASE THE FIRE DANGER.  
 

 
   
GYX WATCHES/WARNINGS/ADVISORIES
 
 
ME...NONE.  
NH...NONE.  
MARINE...NONE.  
 

 
 

 
 
NEAR TERM...LEGRO  
SHORT TERM...LEGRO  
LONG TERM...KIMBLE  
AVIATION...KIMBLE/LEGRO  
MARINE...KIMBLE/LEGRO  
FIRE WEATHER...LEGRO  
 
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