332
FXUS61 KGYX 091416
AFDGYX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1016 AM EDT FRI MAY 9 2025
SYNOPSIS
A SLOW MOVING LOW PRESSURE BRINGS WIDESPREAD RAINFALL
TODAY THROUGH SATURDAY. RAINFALL COULD BE HEAVY AT TIMES AND
WITH ALREADY SATURATED CONDITIONS IN PARTS OF THE AREA, A MINOR
FLOODING THREAT COULD DEVELOP. THIS RAINFALL WILL PUSH AREA
RIVERS AND STREAMS TO NEAR BANKFULL AND IN SOME CASES INTO MINOR
FLOOD STAGE. THIS COULD RESULT IN A MINOR FLOOD THREAT THROUGH
THE WEEKEND AS RIVERS REMAIN HIGH. WARMER AND DRIER CONDITIONS
RETURN WITH HIGH PRESSURE FOR SUNDAY AND EARLY NEXT WEEK.
NEAR TERM /UNTIL 6 PM THIS EVENING/
1000 AM UPDATE...CURRENT RADAR IMAGERY SHOWS SOME SCATTERED
SHOWERS MOVING NORTHWARD ACROSS NORTHERN NH AND WESTERN ME, WITH
THE BULK OF THE PRECIPITATION STILL TO OUR WEST IN VERMONT. THIS
AXIS OF RAIN POSITIONED OVER THE GREEN MOUNTAINS IS MOVING
EASTWARD SLOWER THAN PREVIOUSLY EXPECTED, LOWERED QPF AMOUNTS A
LITTLE AND TRIMMED BACK POPS TO MATCH MOST RECENT GUIDANCE AND
THE LATER ONSET OF THIS BATCH OF RAIN. IN ADDITION, ADDED PATCHY
FOG TO THE FORECAST AND DAMPENED DOWN HIGH TEMPERATURES A
BIT. THESE CHANGES WERE MADE MAINLY TO ACCOUNT FOR DENSE AND
LOW CLOUDS OVER THE AREA, WITH FOG ALREADY BEING OBSERVED ACROSS
MUCH OF SOUTHERN NH.
625 AM UPDATE...MAINLY JUST REFINED POPS AS SHOWERS CONTINUE TO
PUSH THROUGH THE AREA AHEAD OF THE MORE ORGANIZED AREA OF RAIN
JUST TO OUR SOUTHWEST. OTHERWISE, JUST MINOR UPDATES TO REFLECT
LATEST OBSERVATIONS.
PREVIOUS DISCUSSION...
IMPACTS AND KEY MESSAGES:
* WIDESPREAD SHOWER ACTIVITY TODAY WILL CONTINUE TO PRIME CONDITIONS
FOR A MINOR FLOOD THREAT HEADING INTO THE EVENING.
A WEAKENING AREA OF SHOWERS CONTINUES TO MOVE NORTHWARD ALONG THE
MAINE AND NEW HAMPSHIRE BORDER. RAIN RATES WERE MODERATE OVERNIGHT
AT TIMES WITH A GOOD NUMBER OF GAUGES PICKING UP AROUND A HALF INCH
OVER THE LAST 6 HOURS IN SOUTHERN AND CENTRAL NEW HAMPSHIRE. A FEW
SHOWERS ARE PUSHING INTO SOUTHWESTERN NEW HAMPSHIRE, RATES AT THIS
HOUR ARE LIGHT. MUCH OF THE AREA WILL ACTUALLY BE MOSTLY DRY THIS
MORNING AS AN UPPER LOW CONTINUES IT'S APPROACH. CURRENT RAP13
ANALYSIS PUTS IT OVER THE GREAT LAKES REGION, WITH THE SURFACE LOW
JUST EMERGING OFF THE DELMARVA COAST. THE SHOWERS ASSOCIATED WITH
THIS LOW ARE CURRENTLY IN EASTERN PENNSYLVANIA AND WILL BEGIN TO
ENTER OUR AREA EARLY THIS AFTERNOON, OVERSPREADING THE AREA FROM
WEST TO EAST. PWATS WON'T BE AS HIGH AS LATER IN THE EVENING AT THIS
POINT, BUT MODERATE RAIN RATES ARE STILL LIKELY. WHILE FLOODING
ISSUES AREN'T EXPECTED AT THE INITIAL ONSET OF THESE SHOWERS, THIS
WILL BE A GOOD PRIMER AHEAD OF EXPECTED INCREASED RATES LATER.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/
IMPACTS AND KEY MESSAGES:
* THE HEAVIEST RAINFALL RATES ARE EXPECTED TO OCCUR FRIDAY NIGHT.
WITH VERY WET ANTECEDENT CONDITIONS MINOR FLOODING OF POOR
DRAINAGE AREAS.
* AREA RIVERS AND STREAMS ARE EXPECTED TO SEE RISES THROUGH SATURDAY
WITH A COUPLE OF THEM REACHING MINOR FLOOD STAGE.
TONIGHT: THE UPPER LEVEL LOW BEGINS TO PHASE WITH SURFACE LOW
PRESSURE JUST TO OUR SOUTH. THIS WILL HELP TO AMPLIFY THE SURFACE
LOW INCREASING COVERAGE AND INTENSITY OF SHOWERS. A 35KT LOW LEVEL
WILL ALSO HELP TO INCREASE RATES BY STARTING THE MOISTURE SURGE
DURING THIS PERIOD. LATEST HI-RES GUIDANCE SUGGESTS WIDESPREAD PWATS
AROUND AN INCH OVER THE SOUTHERN HALF OF NEW HAMPSHIRE AND THE
COASTAL PLAIN. THE OVERNIGHT PERIOD IS LIKELY TO BE WHERE WE WOULD
SEE THOSE MINOR FLOODING ISSUES BEGIN IN URBAN AND POOR DRAINAGE
AREAS AS AN UPPER LEVEL LOW MOVING OVERHEAD LEADS TO SHOWERS
ORIENTING THEMSELVES IN A SOUTH TO NORTH FASHION. WITH ALREADY VERY
WET CONDITIONS ACROSS SOUTHERN NEW HAMPSHIRE, TRAINING OR JUST
REPEATED ROUNDS OF HEAVY SHOWERS COULD BEGIN TO CAUSE SOME AREAL
FLOOD ISSUES. FOR FURTHER DETAILS ON THE GENERAL FLOOD THREAT SEE
THE HYDROLOGY SECTION BELOW.
SATURDAY: WIDESPREAD RAIN SHOWERS WILL BE ONGOING SATURDAY MORNING
AS LOW PRESSURE BECOMES VERTICALLY STACKED OVER THE AREA. THE
MOISTURE AXIS CONTINUES MOVING NORTH AND EAST AS WELL SO HEAVY
RAINFALL RATES WILL REMAIN PRESENT WITH SOUTHEASTERLY FLOW DIRECTLY
OFF THE ATLANTIC PUSHING PWATS UP TOWARD 1.25" ON THE COASTAL PLANE.
HEADING TOWARD THE AFTERNOON WE WILL BEGIN TO SEE RAINFALL RATES
DECREASE AND SHOWERS CLEAR FROM SOUTHWEST TO NORTHEAST AS LOW
PRESSURE MAKES A SWIFT EXIT AND FLOW TURNS NORTHWESTERLY. WHEN ALL
IS SAID AND DONE QPF AMOUNTS LOOK TO BE A WIDESPREAD 1.5-2 INCHES
WITH LOCALLY HIGHER AMOUNTS NEARING 3 INCHES POSSIBLE. THE EXCEPTION
WILL BE NORTH OF THE MOUNTAINS WHERE SOME SHADOWING MAY KEEP AMOUNTS
MORE IN THE 1-1.5 INCH RANGE. PLENTY OF CLOUDS AND RAIN WILL LIMIT
HIGH TEMPERATURES TO THE UPPER 40S AND LOW 50S. BY SATURDAY EVENING
THE AREA LOOKS PRETTY MUCH PRECIPITATION FREE, BUT RUNOFF FROM THE
RECENT RAINS WILL CONTINUE TO DUMP INTO AREA RIVERS PUSHING THEM TO
BANKFULL OR EVEN INTO MINOR FLOOD STAGE IN A COUPLE CASES. BREEZY
NORTHWESTERLY WINDS FOLLOW IN THE WAKE OF THE DEPARTING LOW ALONG
WITH CLEARING SKIES.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
LONG TERM UPDATE...VERY LITTLE CHANGE TO THE LONG TERM FORECAST
AT THIS TIME. 01Z NBM IS IN LINE WITH PREVIOUS FORECASTS AND
OTHER ENSEMBLE DATASETS AS WE CAN EXPECT DRYING AND WARMING FOR
SUNDAY INTO EARLY NEXT WEEK.
PREVIOUSLY...
OTHER THAN A FEW SHOWERS ACROSS NORTHERN AREAS LATE MONDAY INTO
MONDAY NIGHT, A RIDGE OF HIGH PRESSURE BUILDS TOWARD THE
NORTHEASTERN US SUNDAY INTO EARLY NEXT WEEK, OFFERING A STRETCH
OF DRY AND WARMER WEATHER. SUNDAY'S TEMPS EXPECTED TO BE THE MID
60S TO LOW 70S, BUT THEN THE LOW-LEVEL HIGH SHIFTS TO THE SOUTH
AND EAST EARLY NEXT WEEK, BRINGING A RETURN TO MORE SOUTH TO
SOUTHWEST FLOW THAT WILL USHER IN EVEN WARMER TEMPERATURES THAT
MAY STICK AROUND THROUGH MIDWEEK. FOR MONDAY, EXPECTING
GENERALLY 70S OVER MUCH OF THE AREA, EXCEPT THE ONSHORE
COMPONENT WILL PROBABLY KEEP THE COAST AND EASTERN AREAS IN THE
60S. GUIDANCE HAS THEN TRENDED WARMER FOR TUES-WEDS WITH 70S
LOOKING MORE LIKELY ACROSS THE INTERIOR WITH LOW 80S EVEN
POSSIBLE AS HEIGHTS CONTINUE TO RISE, BUT THE COAST WILL
PROBABLY STAY A BIT COOLER WITH THE SEA BREEZE.
FOR WEDNESDAY AND THURSDAY, THERE'S GOOD AGREEMENT IN BRINGING
AN UPPER TROUGH TOWARD THE EAST COAST, BUT THE DIFFERENCES ARE
WHERE. THERE'S SUPPORT FOR THE RIDGE HOLDING STRONG OVER NEW
ENGLAND TO KEEP THE TROUGH SOUTH, WHICH WOULD PROLONG THE DRY
AND WARM STRETCH. ON THE OTHER HAND, THERE'S ALSO SOME SUPPORT
WITHIN THE ENSEMBLES TO WEAKEN THE RIDGE AND SHIFT IT TO THE
EAST, WHICH BRING THE NEXT CHANCE OF SHOWERS. THE NBM 20% POPS
WEDNESDAY AND THEN 30% FOR NEXT THURSDAY ARE GOOD FOR NOW GIVEN
THE UNCERTAINTY.
AVIATION /14Z FRIDAY THROUGH TUESDAY/
SHORT TERM...NOT MUCH IN THE WAY OF IMPROVEMENT IS EXPECTED
TODAY AS CEILINGS REMAIN LOW BETWEEN ROUNDS OF RAIN. THE NEXT
ROUND OF RAIN ARRIVES LATE/MORNING EARLY AFTERNOON AND WILL
BRING ABOUT VISIBILITY RESTRICTIONS AS IT WILL BE HEAVY AT TIMES
THROUGH TOMORROW. SATURDAY EVENING IS WHEN RAIN WILL TAPER OFF
AND CEILINGS WILL TREND TOWARD VFR.
LONG TERM...LINGERING SHOWERS AND RESTRICTIONS ARE POSSIBLE
INTO SATURDAY EVENING TOWARD RKD/AUG AND THEN HIE THROUGH
SATURDAY NIGHT, BUT IN GENERAL CONDITIONS CONTINUE TO IMPROVE AS
LOW PRESSURE DEPARTS THE REGION. THAT SAID, WILL HAVE TO WATCH
FOR FOG DEVELOPMENT SATURDAY NIGHT GIVEN THE WIDESPREAD RAIN
FRIDAY INTO SATURDAY. VFR EXPECTED SUN-TUES.
MARINE
SHORT TERM...LOW VISIBILITIES IN HEAVY RAIN AND FOG WILL
PERSIST THROUGH SATURDAY AS LOW PRESSURE MOVES THROUGH THE
REGION. THIS WILL ALSO BRING ABOUT SEAS BUILDING TO AROUND 6FT.
NORTHEASTERLY WIND GUSTS WILL NEAR 25KTS TODAY AND SATURDAY
BEFORE SHIFTING TO WESTERLY BY THE END OF THE DAY SATURDAY AS
LOW PRESSURE MAKES ITS JOURNEY UP THE COAST.
LONG TERM...LOW PRESSURE DEPARTS INTO THE CANADIAN MARITIMES
SATURDAY NIGHT, AND NORTHWEST WINDS ON THE BACKSIDE OF THE LOW
COULD EXCEED SCA LEVELS DURING THIS PERIOD. CONDITIONS REMAIN
BELOW SCA LEVELS SUNDAY AND SUNDAY NIGHT AS HIGH PRESSURE BUILDS
IN. IN GENERAL, FLOW LOOKS TO REMAIN SOUTH OR SOUTHWESTERLY FOR
THE EARLY TO MIDDLE PART OF NEXT WEEKEND AS THE HIGH BECOMES
CENTERED SOUTHEAST OF THE WATERS. THERE MAY BE ANOTHER PERIOD OF
SCA CONDITIONS MONDAY INTO MONDAY NIGHT AS THE GRADIENT
TIGHTENS BETWEEN THE HIGH AND A WEAK DISTURBANCE PASSING TO THE
NORTH.
HYDROLOGY
1000 AM UPDATE...ADDED ROCKINGHAM AND STRAFFORD COUNTIES TO THE
FLOOD WATCH, MAINLY TO DUE TO THE MEASURABLE RAINFALL SEEN THERE LAST
NIGHT. THE ADDITIONAL RAIN COULD INCREASE CHANCES FOR SMALL
STREAM FLOODING AND LOCALIZED MINOR MAINSTEM RIVER FLOODING AS
MORE SOAKING RAIN ARRIVES THIS EVENING.
PREVIOUSLY...RECENT SHOWERS HAVE BROUGHT AN AVERAGE OF 1 TO 2
INCHES OF RAINFALL FROM THE MOUNTAINS NORTHWARD, AND 2 TO 4+
INCHES SOUTHWARD OVER THE LAST 7 DAYS. AS A RESULT, STREAMFLOWS
ARE RUNNING ABOVE NORMAL, PARTICULARLY IN THE CONNECTICUT AND
MERRIMACK WATERSHEDS. SOIL MOISTURE LEVELS ARE NEAR 75-95%, AND
DESPITE GREEN-UP THERE REMAINS A LIMITED CAPACITY OF ABSORPTION.
RAINFALL OVERNIGHT THURSDAY WAS GENERALLY 0.25-0.50" WITH SOME
LOCALLY HIGHER AMOUNTS AND WAS HEAVIEST NEAR THE CONNECTICUT
RIVER AND PARTS OF SOUTHERN NEW HAMPSHIRE. CONFIDENCE IS
INCREASING THAT THE TODAY-SAT SYSTEM WILL PRODUCE A WIDESPREAD 1
TO 3 INCHES WITH LOCALLY HIGHER AMOUNTS. REFINEMENT IS NEEDED
ON THE SYSTEM TIMING AND POTENTIAL FOR A DRY SLOT SAT MORNING.
DESPITE THESE DETAILS, THE OVERALL EFFECT WILL BE ADDITIONAL
STREAM RISES WHICH IS LIKELY TO CAUSE SMALL STREAM FLOODING AND
LOCALIZED MINOR MAINSTEM RIVER FLOODING. CONFIDENCE IS HIGH THAT
THE RAINFALL WILL BE INSUFFICIENT TO CAUSE ANY SIGNIFICANT
FLOODING OF MODERATE SEVERITY OR HIGHER. PONDING ON ROADWAYS,
PARTICULARLY IN URBAN, LOW LYING, OR POOR DRAINAGE AREAS COULD
BECOME PROBLEMATIC FRIDAY NIGHT INTO SATURDAY.
GYX WATCHES/WARNINGS/ADVISORIES
ME...FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH SATURDAY
EVENING FOR MEZ012.
NH...FLOOD WATCH FROM 2 PM EDT THIS AFTERNOON THROUGH SATURDAY
EVENING FOR NHZ003>013-015.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT SATURDAY FOR ANZ150-152-
154.
NEAR TERM UPDATE...PALMER
NEAR / SHORT TERM...BARON
LONG TERM...COMBS/EKSTER
HYDROLOGY...BARON/JAMISON/PALMER
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