631  
FXUS61 KGYX 031908  
AFDGYX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAY ME  
308 PM EDT MON AUG 3 2020  
   
SYNOPSIS
 
 
BY LATER TONIGHT WILL START TO SEE SOME SHOWERS ASSOCIATED WITH  
ISAIAS MOVING INTO THE REGION, WHICH WILL BECOME MORE NUMEROUS  
DURING THE DAY ON TUESDAY. THE BRUNT OF THE STORM SHOULD HIT  
TUESDAY NIGHT WITH STRONG WINDS AND LOCALLY HEAVY RAINFALL. THE  
STORM EXITS TO THE NORTH EARLY WEDNESDAY, WITH MORE NORMAL TO  
WARM TEMPERATURES AND LOWER HUMIDITY FOR THE END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
MOISTURE WILL BEGIN TO SPREAD NORTH TONIGHT AHEAD OF TROPICAL  
CYCLONE ISAIAS INTO WESTERN NEW HAMPSHIRE AS A DEEP SOUTHERLY  
FLOW DEVELOPS OVER THE REGION. LOWS WILL REMAIN IN THE MID TO  
UPPER 60S OVER SOUTHERN AREAS AS THIS MOISTURE ADVANCES INTO THE  
REGION AT ALL LEVELS.  
 

 
   
SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/
 
 
SHOWERS BECOME MORE NUMEROUS DURING THE DAY TUESDAY AS WINDS  
INCREASE FROM THE SOUTH. PRECIPITABLE WATER LEVELS WILL BECOME  
VERY HIGH ONCE AGAIN. THIS DEEP MOISTURE ADVECTING POLEWARD WILL  
ALLOW FOR HEAVY SHOWERS. DESTABILIZATION OF THE ATMOSPHERE WILL  
ALLOW FOR A FEW THUNDERSTORMS AS WELL.  
 
AS ISAIAS CONTINUES TO TRACK NORTH, PLENTY OF SHEAR WILL BE  
PRESENT. AN ISOLATED THUNDERSTORM OR TWO MAY LEAD TO THE  
POSSIBILITY OF A TORNADO TUESDAY NIGHT AS THE SYSTEM TRACKS INTO  
AND THROUGH OUR AREA. IN GENERAL, 12Z MODEL GUIDANCE SUGGESTS  
THE TIMING OF THIS SYSTEM WILL BE FASTER THAN PREVIOUS RUNS WITH  
MOST OF THE RAINFALL EXITING INTO CANADA BY WEDNESDAY MORNING.  
SLIGHT WESTWARD ADJUSTMENTS CONTINUE FOR THE TRACK.  
 
GUSTY SOUTH TO SOUTHEASTERLY WINDS WILL CONTINUE WITH THE  
PASSAGE OF THE CYCLONE AS IT MOVES UP THE CONNECTICUT RIVER  
VALLEY TUESDAY NIGHT. STRONGEST GUSTS WILL BE OVER THE SOUTH  
FACING HIGHER TERRAIN AND THE SHORELINE.  
 

 
   
LONG TERM /WEDNESDAY THROUGH MONDAY/
 
 
FIRST THINGS FIRST... WEDNESDAY SEES THE EXPEDITED DEPARTURE OF  
TROPICAL STORM ISAIAS, OR ITS REMNANTS. BY THEN, THE SYSTEM  
WILL BE UNDERGOING OR WILL HAVE UNDERGONE EXTRATROPICAL  
TRANSITION AS A NORTHERN STREAM TROUGH OVER THE GREAT LAKES  
SWINGS AN AXIS ACROSS THE NORTHEAST WEDNESDAY WITH A DRYING,  
WESTERLY BREEZE IN ITS WAKE. LATEST MODEL GUIDANCE SUGGESTS THE  
SHIELD OF STRATIFORM RAINFALL ASSOCIATED WITH THE SYSTEM IS MORE  
OR LESS OUT OF OUR FORECAST AREA AND INTO NORTHERN MAINE BY  
12Z/8AM WEDNESDAY; THERE REMAINS SOME UNCERTAINTY IN THE FORWARD  
SPEED AND GENERAL TIMING OF THE TROPICAL SYSTEM WITH SIGNIFICANT  
ACCELERATION EXPECTED AS IT TRAVELS UP THE COAST, BUT LATEST  
MODEL GUIDANCE IS CONVERGING ON THE SYSTEM CENTER LOFTING INTO  
THE LOWER ST LAWRENCE VALLEY BY 12Z. SOME WRAP AROUND MOISTURE  
MAY GENERATE A FEW RAIN SHOWERS OVER THE MOUNTAINS DURING THE  
DAY WEDNESDAY BEFORE DRYING ENTIRELY BY THAT NIGHT. SOME OF  
THOSE SHOWERS MAY TRACK INTO THE LOWER ELEVATIONS, BUT WOULD BE  
MINOR AND THERE ISN'T CONFIDENCE TO INCLUDE IN THE FORECAST FOR  
NOW. TEMPERATURES WILL WARM INTO THE 70S AND 80S AS SKIES CLEAR  
OUT WITH A WEST TO SOUTHWEST BREEZE AT ABOUT 10 KTS (AFTER  
GUSTIER WINDS FROM THE STRATIFORM SHIELD EXIT TO THE NORTH).  
 
BEYOND WEDNESDAY, THE LONG RANGE FORECAST LOOKS FAIRLY QUIET.  
HIGH PRESSURE BUILDS AT THE SURFACE OVER THE NORTHEAST CONUS  
WITH PERSISTENT SW FLOW ALOFT AS A TROUGH HANGS BACK OVER THE  
GREAT LAKES REGION AND RIDGING HOLDS OVER THE ATLANTIC. THURSDAY  
WILL BE QUITE NICE WITH HIGHS IN THE 70S TO MID-80S AND LOWERED  
DEW POINTS IN THE 50S UNDER MOSTLY SUNNY SKIES. AFTER THAT, A  
WARM TREND CARRIES INTO THE START OF NEXT WEEK WITH STEADILY  
INCREASING DEW POINTS. HIGHS WILL ONCE AGAIN APPROACH 90 OVER  
INTERIOR/SOUTHERN LOCATIONS BY THE START OF NEXT WEEK. A FEW  
SHORTWAVES CROSS TO THE NORTH THIS WEEKEND INTO NEXT WEEK WITH  
AFTERNOON SHOWERS OVER THE MOUNTAINS POSSIBLE.  
 

 
   
AVIATION /19Z MONDAY THROUGH SATURDAY/
 
 
SHORT TERM...PATCHY FOG IS POSSIBLE OVER A COUPLE OF THE  
INTERIOR VALLEYS TONIGHT. OTHERWISE, CONDITIONS DETERIORATING  
FROM WEST TO EAST LATE TONIGHT INTO TUESDAY AS SHOWERS AHEAD OF  
ISAIAS MOVE NORTHEAST. LIFR CONDITIONS TUESDAY NIGHT IN HEAVY  
SHOWERS.  
 
LONG TERM...WESTERLY TO WSWERLY WINDS AT AROUND 10 KTS WEDNESDAY  
WITH CONDITIONS IMPROVING TO VFR EARLY AS THE REMNANTS OF ISAIAS  
LOFT NORTH OUT OF THE AREA. AFTERWARD... VFR PREVAILS WITH HIGH  
PRESSURE MOVING INTO THE AREA.  
 

 
   
MARINE
 
 
SHORT TERM...STRONG SOUTH TO SOUTHEASTERLY WINDS EXPECTED WITH  
THE PASSAGE OF ISAIAS TUESDAY NIGHT. A TROPICAL STORM WATCH  
REMAINS IN EFFECT. SEAS WILL BE BUILDING TO AROUND OR JUST OVER  
10 FEET BY THE TIME OF HIGH TIDE TUESDAY NIGHT.  
 
LONG TERM...THE REMNANTS OF ISAIAS WILL BE LOFTING NORTH INTO  
THE ST LAWRENCE WEDNESDAY AND WELL AWAY FROM THE GULF OF MAINE,  
ALLOWING SEAS TO GRADUALLY SUBSIDE. SEAS WILL LINGER AROUND 5 FT  
OVER THE OUTER WATERS, ESPECIALLY TOWARD THE MAINE MIDCOAST,  
INTO WEDNESDAY EVENING BEFORE HIGH PRESSURE BUILDS INTO THE  
REGION. QUIET OVER THE WATERS FOR THE END OF THE WEEK AND  
WEEKEND.  
 

 
   
HYDROLOGY
 
 
SHOWERS AND THUNDERSTORMS COULD PRODUCE TORRENTIAL DOWNPOURS TUESDAY  
AHEAD OF ISAIAS, BUT HEAVIEST RAINFALL IS LIKELY LATE TUESDAY  
AND TUESDAY NIGHT. WESTERN AREAS CAN EXPECT THE HIGHEST  
RAINFALL TOTALS, ESPECIALLY ACROSS THE HIGHER TERRAIN IN THE  
MOUNTAINS WHERE SOUTHEASTERLY UPSLOPING MAY OCCUR. TWO TO FOUR  
INCHES OF RAIN CAN BE EXPECTED THROUGHOUT THE REGION WITH  
POTENTIALLY LOCALLY HIGHER AMOUNTS IN THE HIGHER TERRAIN. FLASH  
FLOODING AND RIVER FLOODING WILL ALSO BE POSSIBLE WITH THIS  
SYSTEM, HENCE A FLASH FLOOD WATCH HAS BEEN ISSUED.  
 

 
   
TIDES/COASTAL FLOODING
 
 
A MODESTLY HIGH ASTRONOMICAL TIDE WILL OCCUR SHORTLY AFTER  
MIDNIGHT TUESDAY NIGHT. AS THE REMAINS OF ISAIAS PASS BY TO OUR  
WEST, A STRONG SOUTH TO SOUTHEASTERLY FLOW MAY COINCIDE WITH  
THIS TIDE DEPENDING ON THE EXACT TIMING WITH THE SYSTEM.  
BUILDING SEAS AND GUSTY ONSHORE WINDS MAY ALLOW FOR ABOUT A FOOT  
OR SO OF STORM SURGE (CURRENT MODEL RUNS APPEAR TO HAVE A LOW  
BIAS). THIS MAY LEAD TO LOCALIZED SPLASH-OVER ACROSS THE REGION  
TUESDAY NIGHT. TIMING OF THE SYSTEM WILL CRITICAL.  
 

 
   
GYX WATCHES/WARNINGS/ADVISORIES
 
 
ME...TROPICAL STORM WATCH FOR MEZ007>009-012>014-018>028-033.  
FLASH FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY  
NIGHT FOR MEZ007>009-012-013.  
NH...TROPICAL STORM WATCH FOR NHZ001>015.  
FLASH FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY  
NIGHT FOR NHZ001>009-011-015.  
MARINE...TROPICAL STORM WATCH FOR ANZ150>154.  

 
 

 
 
CANNON/CASEY  
 
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