759  
FXUS61 KGYX 291803  
AFDGYX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE GRAY ME  
203 PM EDT TUE JUL 29 2025  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL MAINTAIN HEAT AND HUMIDITY ONE MORE DAY. A SLOW  
MOVING COLD FRONT WILL PUSH THROUGH THE REGION LATE WEDNESDAY  
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS. THE FRONT WILL STALL  
OVER SOUTHERN NEW HAMPSHIRE THURSDAY SUPPORTING MORE WIDESPREAD  
RAINFALL FOR AREAS SOUTH OF THE MOUNTAINS. HIGH PRESSURE WILL  
THEN BUILD FROM THE NORTH INTO THE WEEKEND, WITH BELOW NORMAL  
TEMPERATURES, MUCH DRIER AND PLEASANT CONDITIONS EXPECTED.  
 
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
WEAK HIGH PRESSURE OVER THE NORTHEAST WILL PROVIDE QUIET WEATHER  
TONIGHT INTO WEDNESDAY MORNING. LIGHT WINDS AND MOSTLY CLEAR SKIES  
WILL ALLOW FOR SOME RADIATIONAL COOLING WITH LOWS RANGING FROM THE  
MID 50S ACROSS THE NORTH TO MID 60S ACROSS THE SOUTH. A MOIST  
AIRMASS IN PLACE WILL LIKELY PROMOTE FOG FORMATION OVERNIGHT WITHIN  
INTERIOR VALLEYS AND NEAR THE MID COAST.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/
 
 
WEDNESDAY WILL BE THE LAST VERY WARM AND HUMID DAY BEFORE TROUGH DESCENDING  
OUT OF CANADA SENDS A COLD FRONT INTO THE AREA WEDNESDAY AFTERNOON.  
THE 12Z MODEL SUITE GENERALLY SUGGESTS THERE WILL BE MORE SUN  
THAN CLOUDS WEDNESDAY MORNING, ESPECIALLY SOUTH OF THE MOUNTAINS.  
TEMPERATURES AT 850 MB WILL BE SLIGHTLY COOLER THAN TODAY  
RESULTING IN HIGHS MAINLY IN THE MID TO UPPER 80S WITH SOME LOW  
90S LIKELY ACROSS SOUTHERN NH. DEWPOINTS WILL MAINLY BE IN THE  
MID TO UPPER 60S WHILE MIXING MAY HELP LOWER DEWPOINTS ACROSS  
THE WARMEST AREAS IN SOUTHERN NH. THIS WILL LEAD TO HEAT INDICES  
LARGELY STAYING IN THE LOW 90S WITH SOME MID 90S POSSIBLE NEAR  
THE LOWER MERRIMACK VALLEY.  
 
A COLD FRONT WILL START TO SAG SOUTH INTO THE AREA WEDNESDAY AFTERNOON  
AND WILL PROVIDE A FORCING MECHANISM FOR THUNDERSTORMS THROUGH THE  
EVENING. THE TROUGH DESCENDING SOUTH FROM CANADA WILL BRING INCREASING  
WESTERLY FLOW ALOFT THAT WILL CONTRIBUTE TO AROUND 45 KTS OF EFFECTIVE  
SHEAR. THIS AMOUNT OF SHEAR WILL BE FAVORABLE FOR ORGANIZED CONVECTION  
AND POSSIBLY SOME SUPER CELL STRUCTURES. THE 12Z HREF HAS COME IN  
SLIGHTLY MORE BULLISH ON A FEW STORMS TRACKING SOUTHEAST ACROSS THE  
AREA WITH SUSTAINED ROBUST UPDRAFTS. THERE CONTINUES TO BE A FAIR  
AMOUNT OF SPREAD AMONGST INDIVIDUAL HREF MEMBERS ON BOTH THE AREAL  
COVERAGE AND INTENSITY OF STORMS WITH THIS SPREAD DRIVEN BY SOME  
MEMBERS LIMITING ML CAPE TO AROUND 500 J/KG AND THE MORE BULLISH  
MEMBERS BRINGING ML CAPE UPWARDS OF 1500 J/KG. SHEAR MAGNITUDE  
AND STRAIGHT HODOGRAPHS SUGGEST HAIL WILL BE POSSIBLE ALONG WITH  
INVERTED V SOUNDINGS BRINGING THE POTENTIAL FOR DAMAGING WINDS  
WITH THE STRONGER CELLS. SPC HAS EXPANDED THE MARGINAL RISK FARTHER  
NORTH THROUGH MUCH OF THE AREA, WHICH SEEMS REASONABLE GIVEN SOME  
CAM SOLUTIONS INITIATE STORMS NEAR THE CANADIAN BORDER MID AFTERNOON  
WITH THESE STORMS TRACKING ESE INTO THE EVENING.  
 
CONVECTION WILL WANE INTO WEDNESDAY EVENING WITH THE LOSS OF  
HEATING. THE COLD FRONT WILL LOSE ITS SOUTHWARD MOMENTUM AND MAY  
STALL NEAR THE NH/MA BORDER OVERNIGHT. THIS WILL LEAD TO MOSTLY  
CLOUDY SKIES WITH CHANCES FOR SHOWERS ACROSS THE SOUTHERN HALF OF  
THE AREA. LOWS WILL RANGE FROM THE MID 50S NORTH TO LOW 60S ACROSS  
THE SOUTH.  
 

 
   
LONG TERM /THURSDAY THROUGH TUESDAY/
 
 
KEY MESSAGES  
 
- COLD FRONT WILL BRING RAIN AND RELIEF FROM THE HEAT THURSDAY  
 
- COMFORTABLE DAYTIME HIGHS AND COOL NIGHTS THIS WEEKEND  
 
- MOSTLY DRY CONDITIONS THROUGH MONDAY  
 
THIS WILL BE THE TRANSITION POINT IN THE FORECAST AS A COLD FRONT  
BRINGS MUCH NEEDED RELIEF TO THE RECENT HEAT. THE COLD FRONT WILL  
SLOWLY SAG OVER THE SOUTHERN PART OF OUR AREA BY THURSDAY  
MORNING, HOWEVER MODEL GUIDANCE CONTINUES TO STRUGGLE WITH JUST  
HOW FAR SOUTH THIS BOUNDARY WILL PROGRESS BEFORE TEMPORARILY  
STALLING OUT. POPS WERE INCREASED TO ACCOUNT FOR THE SLOW MOVING  
FRONT, PEAKING ACROSS SOUTHERN NH AND TAPERING OFF QUICKLY NEAR  
THE MOUNTAINS AND NORTHWARD. SOME CONCERN EXIST FOR EXCESSIVE  
RAIN AS DIURNAL INSTABILITY AND SOME FRONTOGENETIC FORCING FROM  
A COUPLE OF WAVES GENERATING MULTIPLE ROUNDS OF RAINFALL  
ACTIVITY EVEN INTO THE OVERNIGHT, WITH SOME ENSEMBLE MEMBERS  
SHOWING 2" OR MORE QPF ACROSS SOUTHERN NH. PWAT GRADIENT WILL BE  
TIGHT, UPWARDS OF 1.7" IN THE SOUTH, AND UNDER 1.0" IN THE  
NORTH, TRANSLATING TO NOMINAL RAINFALL FROM THE FOOTHILLS  
NORTHWARD. AT THIS TIME, MESOSCALE DETAILS REMAIN TO BE SEEN SO  
DETERMINING RAINFALL AMOUNTS WOULD BE TRICKY. EXTENSIVE CLOUD  
COVER ALONG WITH COLD AIR ADVECTION WILL FAVOR A COOL DAY, WITH  
HIGHS IN THE 70S.  
 
THE FINAL PUSH OF THE FRONT WILL COME WITH A ROBUST SHORTWAVE TROUGH  
EARLY FRIDAY, FINALLY CLEARLY OUT RAIN IN SOUTHERN AREAS. THIS WILL  
USHER IN COOLER AND LESS HUMID AIR FROM CANADIAN HIGH PRESSURE  
WITH TEMPS AND DEWPOINTS 10 DEGREES BELOW NORMAL. SURFACE HIGH  
PRESSURE WILL DOMINATE THE WEATHER INTO MONDAY, WITH BELOW  
AVERAGE TEMPERATURES AND PARTICULARLY COOL NIGHTS. TEMPERATURES  
WILL START TO CREEP BACK UP NEXT WEEK, THOUGH HUMIDITY LEVELS  
REMAIN COMFORTABLE THROUGH THE END OF THE FORECAST PERIOD.  
 

 
   
AVIATION /18Z TUESDAY THROUGH SUNDAY/
 
 
SHORT TERM...MAINLY VFR TONIGHT INTO WEDNESDAY, EXCEPT AT KHIE  
AND KLEB WHERE FOG MAY BRING A FEW HOURS OF IFR/LIFR CONDITIONS  
LATE TONIGHT INTO DAY. SOME MARINE FOG MAY ALSO IMPACT KRKD  
OVERNIGHT. A FRONT BRINGS SCATTERED STRONG TO SEVERE STORMS  
WEDNESDAY AFTERNOON THAT WILL BRING BOTH A HAIL AND STRONG WIND  
THREAT. COVERAGE LOOKS TO REMAIN SCATTERED ENOUGH TO NOT HAVE  
CONFIDENCE TO PUT TS IN THE TAF. LINGERING CLOUD COVER WEDNESDAY  
NIGHT MAY LOWER TO MVFR THRESHOLDS INTO THURSDAY MORNING.  
 
LONG TERM...THERE WILL BE SEVERAL CHANCES FOR SUB-VFR CIGS AND  
VIS THURSDAY WHEN A COLD FRONT BRINGS ROUNDS OF SHOWERS TO THE  
S NH TERMINALS AND AS FAR NORTH AS CON AND PWM. NORTHERN  
TERMINALS WILL BE VFR. HIGH PRESSURE BUILDS IN LEADING TO  
PREVAILING VFR FOR THE WEEKEND.  
 

 
   
MARINE
 
 
SHORT TERM...WINDS AND SEAS REMAIN BELOW SCA THRESHOLDS THROUGH  
WEDNESDAY NIGHT. A COLD FRONT WILL TRIGGER THUNDERSTORMS OVER  
THE LAND THAT MAY MAINTAIN THEIR STRENGTH AS THEY TRACK OFFSHORE  
WEDNESDAY EVENING THAT COULD BRING STRONG WINDS AND HAIL.  
 
LONG TERM...A COLD FRONT CRAWLS OFFSHORE EARLY THURSDAY  
MORNING, AND STALLS OVER THE GULF OF MAINE FOR MUCH OF THE DAY.  
WINDS WILL VEER BEHIND THE FRONT BUT REMAIN 15KT OR LESS. A  
SHORTWAVE IS EXPECTED TO CROSS AND FINALLY DRIVE THE FRONT  
FURTHER SOUTH OVERNIGHT, SUPPORTING STRONGER NE WINDS AROUND  
20KT FOR FRIDAY. A SECOND SURGE COMES SATURDAY, KEEPING WINDS  
15-20KT OUT OF THE NE. 1-3 FT SEAS AT THE START OF THE PERIOD  
WILL BUILD TO 2-3 FT BY LATE THURSDAY. PROLONGED NORTHEASTERLY  
FETCH WILL BUILD SEAS FROM NORTH TO SOUTH FRIDAY NIGHT INTO  
SATURDAY. HIGHEST WAVES ON SATURDAY WILL BE AROUND 4FT OFF THE  
NH COAST. SCA CONDITIONS ARE BRIEFLY POSSIBLE GIVEN UNCERTAINLY  
WITH THE FRONT AND TIMING/STRENGTH OF SHORTWAVES. HIGH PRESSURE  
THEN BUILDS IN FOR THE REMAINDER OF THE WEEKEND INTO EARLY NEXT  
WEEK WITH FAIR BOATING CONDITIONS.  
 

 
   
GYX WATCHES/WARNINGS/ADVISORIES
 
 
ME...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MEZ023.  
NH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NHZ008-010-  
012>015.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...JAMISON  
NEAR TERM...SCHROETER  
SHORT TERM...SCHROETER  
LONG TERM...JAMISON  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab ME Page
The Nexlab NH Page Main Text Page