897  
FXUS61 KGYX 260448 AAA  
AFDGYX  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE GRAY ME  
1248 AM EDT FRI MAY 26 2017  
   
SYNOPSIS
 
 
A BROAD AREA OF LOW PRESSURE FROM THE OHIO VALLEY THROUGH THE  
MID ATLANTIC COAST WILL SLOWLY LIFT NORTHEAST TONIGHT...REACHING  
CAPE COD BY FRIDAY MORNING. LOW PRESSURE WILL CONTINUE  
NORTHEAST INTO THE MARITIMES THROUGH FRIDAY NIGHT. WEAK HIGH  
PRESSURE WILL BUILD OVER THE AREA ON SATURDAY AND WILL SHIFT  
OFFSHORE ON SUNDAY. WEAK LOW PRESSURE OVER THE EASTERN GREAT  
LAKES WILL LIFT NORTH INTO WESTERN QUEBEC SUNDAY NIGHT AND WILL  
DRIVE A COLD FRONT TOWARD THE REGION ON MONDAY. THE FRONT WILL  
SLOWLY CROSS THE AREA LATE MONDAY NIGHT AND TUESDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
UPDATE...HAVE INTRODUCED THUNDER TO THE GRIDS BASED ON LATEST  
TRENDS AND NEAR TERM FORECASTS. LIGHTNING DETECTION IS STILL  
SHOWING PLENTY OF ACTIVITY IN THE CONVECTION MOVING NWD...LESS  
THAN AN HOUR FROM OUR SRN BORDER NOW. SPC MESOANALYSIS SHOWS  
AROUND 500 J/KG MUCAPE LINGERING ALONG THE COAST. THIS IS  
SUPPORTED BY FORECAST SOUNDINGS SHOWING A NICE AREA OF CAPE  
AVAILABLE JUST ABOVE THE LLJ. HEAVY RAIN CONTINUES IN THE  
FORECAST AS WELL...WITH SRN NEW ENGLAND ASOS/AWOS REPORTS  
SHOWING 0.50 TO 0.75 INCHES IN AN HOUR.  
 
I WILL ALSO LET THE COASTAL FLOOD HEADLINES EXPIRE ON TIME.  
 
1045PM UPDATE...  
INITIAL BATCH OF RAIN HAS DEVELOPED AND BEGUN PUSHING ONSHORE  
OVER MUCH OF MAINE THIS EVENING, WHILE ANOTHER MORE SUBSTANTIAL  
AREA OF RAIN IS FINALLY TAKING SHAPE TO THE SOUTH OF RHODE  
ISLAND. HRRR MODEL IS HANDLING BOTH AREAS OF RAIN QUITE WELL,  
AND BASED THE FORECAST UPDATE LARGELY ON THIS. PRECIPITATION  
FROM THE HEAVIER BAND TO THE SOUTH SHOULD BE ARRIVING IN  
SOUTHERN NEW HAMPSHIRE AROUND MIDNIGHT. THUNDERSTORMS ARE  
CURRENTLY NOTED WITH THIS ACTIVITY AS IT IS FORMING. AS THIS  
WRAPS AROUND THE LOW, EXPECT THE THUNDERSTORM ACTIVITY TO  
DECREASE A BIT, BUT THERE COULD STILL BE SOME RUMBLES OF THUNDER  
ACROSS THE SOUTHERN PART OF OUR AREA OVERNIGHT AS THIS LOW WINDS  
UP. HAVE INCREASED PRECIPITATION AMOUNTS AS WELL, AS EVEN THIS  
EARLIER AREA OF RAIN FORMING ALONG THE COAST OF MAINE HAS  
PRODUCED SOME DECENT RAINFALL RATES. AREA MOVING IN FROM THE  
SOUTH COULD PRODUCE RATES UP TO ABOUT AN INCH PER HOUR, THOUGH  
THE HEAVIEST RAIN SHOULD ONLY LAST AN HOUR OR TWO BEFORE  
BECOMING LIGHT AND DRIZZLY.  
 
945PM UPDATE...  
GETTING A FEW REPORTS OF HIGH, GUSTY WINDS. HAVE INCREASED WIND  
FORECAST FOR THE OVERNIGHT HOURS, ESPECIALLY THROUGH 06Z WHERE  
BEST WIND FIELDS WILL BE IN PLACE FROM THE NORTHEAST.  
 
OTHERWISE, HAVE UPDATED THE FORECAST BASED ON CURRENT  
CONDITIONS AND LATEST SET OF MESOSCALE MODELS. RAIN CONTINUES TO  
SPREAD NORTH AND EAST, HOWEVER IT REMAINS FAIRLY LIGHT AND  
FRAGMENTED IN MOST AREAS. HEAVIEST PRECIPITATION REMAINS OVER  
UPSTATE NEW YORK WELL TO OUR WEST. HOWEVER, SATELLITE IMAGERY  
CONTINUES TO SHOW A LARGE PLUME OF MOISTURE FORMING OFF THE MID  
ATLANTIC COASTLINE AND MOVING QUICKLY TO THE NORTH. MESOSCALE  
MODELS HAVE THIS HEAVIER PRECIPITATION ARRIVING FROM SOUTH TO  
NORTH WITHIN THE 06Z AND 12Z TIME FRAME.  
 
HAVE MADE MINOR ADJUSTMENTS TO POPS AND TEMPERATURES FOR THE  
NEXT 6 HOURS. AREAS OF LIGHT RAIN WILL CONTINUE WITH DOWNSLOPING  
OVER THE NORTHERN CONNECTICUT RIVER VALLEY.  
 
ORIGINAL DISCUSSION...  
HIGHER PRESSURE AND EASTERLY WINDS HAVE KEPT MUCH RAIN FROM  
INTRUDING INTO NORTHERN NEW ENGLAND BY RETARDING THE ADVANCEMENT  
OF PRECIPITATION INTO MAINE AND NORTHERN AND CENTRAL NH UNTIL  
THE LAST COUPLE OF HOURS. THE FLOW HAS INTENSIFIED ALONG THE  
COAST AS THE PRESSURE GRADIENT INCREASES/LOW PRESSURE NEARS.  
TEMPERATURES HAVE BEEN KEPT DOWN IN THIS MARINE AIRMASS WHILE  
NORTHERN SECTIONS WERE ABLE TO BREAK OUT INTO THE 60S.  
 
CAM MODELS HAVE BEEN CORRECT IN SHOWING A WEAKNESS THIS  
AFTERNOON IN PRECIPITATION FIELDS OVER NH AND ESPECIALLY MAINE  
AS ENERGY DIVERGES BOTH TOWARDS NORTHERN NY STATE AS WELL AS  
OFFSHORE. WE'LL SEE A BREAK IN MOST SHOWER ACTIVITY MORE OR  
LESS THIS AFTERNOON AND EVENING...HOWEVER THERE WILL BE WIDELY  
SCATTERED SHOWERS STILL AROUND...MAINLY OVER THE MOUNTAINS.  
AROUND MIDNIGHT A STRONGER SHORT WAVE ASSOCIATED WITH THIS  
SYSTEM WILL PIVOT INTO THE AREA AND PRECIPITATION WILL INCREASE  
BOTH IN INTENSITY AND AREAL COVERAGE. THIS IS WHEN WE WILL SEE  
THE BULK OF THE 1-2 INCHES WITH THIS EVENT. WE'LL SEE SOME HEAVY  
DOWNPOURS FOR THE OVERNIGHT PERIOD INTO FRIDAY MORNING.  
 
WINDS ARE PICKING UP AS MIXING DEEPENS TODAY AND EXPECT ESE  
WINDS TO GUST TO 25 KT THROUGH THE NIGHT. CONTINUED WITH  
DRIZZLE TONIGHT MAINLY IN BETWEEN THE TWO SYSTEMS AS THE ONSHORE  
FLOW INTENSIFIES. LOWS WILL BE IN THE UPPER 40S TO AROUND 50.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/
 
 
AFTER THE HEAVIER RAIN EXPECTED DURING THE MORNING  
HOURS...PRECIPITATION TAPERS OFF TO SHOWERS BY FRIDAY AFTERNOON.  
AGAIN THE HEAVIER RAIN WILL BE ALONG THE COAST WITH SOME  
ENHANCEMENT OVER TERRAIN. THE LONG DURATION OF THIS EVENT SHOULD  
PRECLUDE ANY FLOODING ISSUES BUT POOR DRAINAGE AREAS MAY SEE  
SOME BRIEF ISSUES IN HEAVIER RAINFALL THAT OCCURS THROUGH  
TOMORROW. EXPECT TEMPERATURES TO WARM ONLY ABOUT 5-10 DEGREES  
FROM OVERNIGHT LOWS TONIGHT TO HIGHS FRIDAY. TOMORROW NIGHT  
CLOUDS WILL BEGIN TO DECREASE ACROSS THE REGION. THE UPPER LOW  
WILL BE ENGULFED IN ANOTHER CIRCULATION SOUTH OF GREENLAND WHILE  
THE SURFACE CYCLONE FILLS. OVERNIGHT LOWS FRIDAY NIGHT WILL  
DROP FARTHER IN A DRIER AIRMASS WITH LOWS IN THE 40S MOST  
LOCATIONS AND PERHAPS UP TO 50 DEGREES IN WARM SPOTS.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
 
 
MEAN LONG WAVE TROF POSITION WILL REMAIN OVER THE GREAT LAKES, THIS  
WILL MEAN A GENERAL COOL WET PATTERN CAN BE EXPECT FOR THE  
OUTLOOK PERIOD WITH A FEW DRY PERIODS BETWEEN SYSTEMS.  
 
STARTING WITH SATURDAY, THE SYSTEM THAT EXITS INTO THE MARITIMES  
ALLOWS WEAK HIGH PRES OVER THE AREA AND A DRIER NORTH TO  
NORTHWEST FLOW TO DEVELOP FOR SATURDAY INTO SUNDAY WITH COOL  
TEMPS. BY LATE SUNDAY INTO MONDAY, THE NEXT SHORT WAVE THAT  
ROTATES AROUND THE BASE OF THE GREAT LAKES TROF THEN MOVES  
NORTHEAST BRINGING ANOTHER PERIOD OF WET WEATHER WITH A  
DEVELOPING ONSHORE FLOW THAT KEEPS TEMPS COOL. WITH THE MEAN  
UPPER TROF REMAINING OVER THE GREAT LAKES THROUGH MID WEEK A  
CONTINUE UNSTABLE SOUTHWEST FLOW WITH EMBEDDED SHORT WAVES WITH  
KEEP UNSETTLED CONDITIONS THROUGH WEDNESDAY. IT APPEARS WE MAY  
FINALLY GET RID OF THE ONSHORE FLOW BY MIDWEEK SO TEMPS MAY  
ACTUALLY GET BACK TO NEAR NORMAL HIGH TEMPS REACHING INTO THE  
70S.  
 

 
   
AVIATION /06Z FRIDAY THROUGH TUESDAY/
 
 
SHORT TERM...IFR/LIFR CEILINGS DEVELOPING TODAY AND PERSISTING  
THROUGH TOMORROW. ESE WINDS WILL GUST TO 25 KTS MOST TERMINALS  
THROUGH TOMORROW. EARLY ON LLWS WILL AFFECT HIE AND LEB TONIGHT.  
DRIZZLE AND FOG WILL AFFECT MOST TAF SITES OUTSIDE OF HIE AND  
LEB TONIGHT BEFORE THE MODERATE TO HEAVY RAIN ARRIVES.  
 
LONG TERM...WINDS AND SEAS GENERALLY LIGHT. NO FLAGS.  
 

 
   
MARINE
 
 
SHORT TERM...CONTINUING SCAS THROUGH FRIDAY AFTERNOON. AT THAT  
POINT WE MAY NEED A SCA JUST FOR HIGH SEAS FOR THE OUTER WATERS.  
 
LONG TERM...CONDITIONS BECOME VFR SAT INTO SUN BEFORE RETURNING TO  
MVFR CONDITIONS FOR SUN NIGHT AND MONDAY AND POSSIBLY THROUGH  
MIDWEEK IN SCATTERED SHOWERS.  
 

 
   
TIDES/COASTAL FLOODING
 
 
HIGHEST ASTRONOMICAL TIDES OF THE YEAR ON TAP FOR TONIGHT AND  
FRIDAY NIGHT. A COASTAL FLOOD ADVISORY REMAINS IN PLACE THE  
MIDCOAST REGION OF MAINE.  
 
THE ASTRONOMICAL TIDE IN PORTLAND IS 11.8 FEET NEAR MIDNIGHT  
TONIGHT. EXPECT AROUND A FOOT OF STORM SURGE OVERNIGHT. FLOOD  
STAGE IN PORTLAND IS 12 FEET AND A STORM TIDE WILL LIKELY BE  
NEAR 13. AREAS OF FLOODING ARE EXPECTED WITH POCKETS OF  
MODERATE FLOODING. HAVE THEREFORE UPGRADED THE COASTAL FLOOD  
ADVISORIES FROM PORTLAND SOUTH TO WARNINGS.  
 
WE MAY NEED A COASTAL FLOOD STATEMENT FOR THE TIDE TOMORROW  
NIGHT DESPITE THE ABSENCE OF AN ONSHORE WIND AS ASTRONOMICAL  
TIDES WILL BE AT THE FLOOD STAGE OF 12.0 FEET IN PORTLAND.  
 

 
   
GYX WATCHES/WARNINGS/ADVISORIES
 
 
ME...COASTAL FLOOD ADVISORY UNTIL 1 AM EDT EARLY THIS MORNING FOR  
MEZ025>028.  
COASTAL FLOOD WARNING UNTIL 1 AM EDT EARLY THIS MORNING FOR  
MEZ023-024.  
NH...COASTAL FLOOD WARNING UNTIL 1 AM EDT EARLY THIS MORNING FOR  
NHZ014.  
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR  
ANZ150>154.  
 

 
 

 
 
NEAR TERM...LEGRO  
 
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