639
FXUS61 KALY 271851
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
251 PM EDT MON JUL 27 2026
WHAT HAS CHANGED
EXCESSIVE RAINFALL OUTLOOK WAS UPGRADED TO A MODERATE RISK
(LEVEL 3 OF 4) FOR THE EASTERN CATSKILLS, LITCHFIELD COUNTY,
CT, WESTERN MASSACHUSETTS, THE MID-HUDSON VALLEY AND CENTRAL AND
SOUTHERN TACONICS. WE ISSUED A FLOOD WATCH FOR THESE AREAS FROM
2 PM TUESDAY AND 8 PM WEDNESDAY IN COLLABORATION WITH
NEIGHBORING WFOS.
KEY MESSAGES
1) ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS TODAY DIMINISH
TONIGHT. AREAS OF RAIN AND THUNDERSTORMS CAPABLE OF HEAVY
DOWNPOURS REDEVELOP TOMORROW AFTERNOON INTO TOMORROW NIGHT WHERE
THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL (LEVEL 2 OF 4)
MAINLY SOUTH OF I-90 GIVEN INCREASED POTENTIAL FOR HEAVY RAIN
TO REPEATEDLY IMPACT A GIVEN AREA.
2) COASTAL LOW LIKELY BRINGS PERIODS OF RAIN FOR TOMORROW NIGHT
THROUGH WEDNESDAY NIGHT, SOME OF WHICH MAY BE HEAVY, ESPECIALLY
NEAR AND SOUTH OF I-90 AND ALONG THE EAST FACING SLOPES OF HIGHER
TERRAIN AREA. THERE IS A LOW TO MODERATE CHANCE FOR ISOLATED TO
SCATTERED INSTANCES OF FLASH FLOODING, HOWEVER THREAT FOR RIVER
FLOODING REMAINS VERY LOW AT THIS TIME.
DISCUSSION
KEY MESSAGE 1...
INSOLATION WITHIN A SLIGHTLY MORE HUMID AIR MASS TODAY HAS
GENERATED SURFACE-BASED INSTABILITY VALUES TO 1000 - 2000
J/KG. LINGERING WEAK TROUGHING OVERHEAD AND ASSOCIATED COOL
POOL ALOFT HAS RESULTED IN ISOLATED TO SCATTERED THUNDERSTORMS
THIS AFTERNOON FOCUSED MAINLY IN THE TERRAIN INCLUDING THE
SOUTHERN GREENS, WESTERN MA, LITCHFIELD HILLS, AND PARTS OF THE
UPPER HUDSON VALLEY. CONVECTION WILL BE MAINLY DIURNALLY DRIVEN
BUT A FEW SHOWERS MAY LAST THROUGH ABOUT MIDNIGHT. VERY WEAK
SHEAR ALOFT WILL KEEP STORM SLOW MOVING AND ALLOW FOR LOCALLY
HEAVY DOWNPOURS TO OCCUR; HOWEVER, SEVERE WEATHER IS NOT
ANTICIPATED.
AS MAIN UPPER LEVEL TROUGH APPROACHES FROM WEST TUESDAY,
INCREASINGLY UPPER LEVEL DIFFLUENT FLOW AND LOW LEVEL
CONVERGENCE WILL ALLOW FOR GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS, ESPECIALLY DURING THE AFTERNOON AND
EVENING HOURS. NEARLY UNI-DIRECTIONAL LOW/MID LEVEL FLOW WILL
ALLOW FOR SOME TRAINING OF SHOWERS/THUNDERSTORMS, LEADING TO
POTENTIAL LOCALLY HEAVY RAINFALL, ESPECIALLY ACROSS THE SE
CATSKILLS AND MID HUDSON VALLEY/NW CT REGIONS, AS WELL AS ACROSS
PORTIONS OF THE MOHAWK VALLEY AND SW ADIRONDACKS. LATEST HREFS
SUGGEST 3-HOUR PROBS FOR >1" RAINFALL AS HIGH AS 70-90% ACROSS
THE SW ADIRONDACKS/MOHAWK VALLEY REGION BETWEEN 21Z/TUE-00Z/WED,
AND 30-70% ELSEWHERE. SIMILAR 3-HOUR PROBS FOR >3" RAINFALL ARE
10-30% ACROSS SW ADIRONDACKS/MOHAWK VALLEY AND SE CATSKILLS/MID
HUDSON VALLEY AFTER 18Z/TUE, HIGHLIGHTING AREAS WITH GREATEST
CHANCES OF HEAVIEST RAINFALL.
FLASH FLOOD GUIDANCE IS GENERALLY QUITE HIGH ACROSS THE REGION
DUE TO FAIRLY DRY ANTECEDENT CONDITIONS, WITH 1 HOUR FFG
GENERALLY 1.5-2.5", AND 3-HOUR FFG GENERALLY 2.5"-3.5", HIGHEST
FOR AREAS NORTH OF I-90. AS SUCH, DESPITE THE LOCALLY HEAVY
RAINFALL POTENTIAL, OVERALL HIGH FFG SUGGESTS MAINLY ISOLATED TO
SCATTERED INSTANCES OF FLASH FLOODING EXPECTED (MARGINAL TO
SLIGHT RISK PER WPC), WITH GREATEST CHANCES MAINLY SOUTH OF
I-90 WHERE FFG IS SLIGHTLY LOWER.
KEY MESSAGE 2...
DIGGING UPPER LEVEL TROUGH IS EXPECTED TO DEVELOP INTO A CLOSED
LOW SOMEWHERE ACROSS CENTRAL/SOUTHERN NY OR NORTHERN PA
WEDNESDAY BEFORE SLOWLY ADVANCING EAST SOUTHEAST WEDNESDAY NIGHT
INTO THURSDAY. DEPENDING ON EXACTLY WHERE THIS SETS UP, AND
RESULTING SURFACE FEATURES TRACK, BANDS OF MODERATE TO HEAVY
RAINFALL MAY PIVOT NORTH AND WEST INTO THE REGION WEDNESDAY INTO
THURSDAY. RAINFALL SHOULD BE MAINLY STRATIFORM, ALTHOUGH SOME
ELEVATED INSTABILITY COULD ALLOW FOR SOME EMBEDDED CONVECTIVE
ELEMENTS.
OVERALL RAINFALL AMOUNTS OF 1-3" ARE CURRENTLY EXPECTED FROM
TODAY THROUGH THURSDAY MORNING, WITH GREATEST AMOUNTS ACROSS THE
SE CATSKILLS DUE TO ENHANCEMENT FROM UPSLOPE FLOW. LOCALLY
HIGHER AMOUNTS OF 3-4" COULD OCCUR IN THESE AREAS, AND ANY OTHER
LOCATIONS WHERE HEAVIER RAINBANDS SET UP AND STALL AND/OR PIVOT.
DESPITE THIS HEAVY RAINFALL, OVERALL GROUNDWATER STORAGE
CAPACITY REMAINS FAIRLY HIGH ACROSS THE REGION, WHICH SHOULD
ALLOW THE GROUND TO SOAK IT UP WITH LOW CHANCES FOR RIVER
FLOODING. LATEST MMEFS (ENSEMBLE RIVER FORECASTS) DO NOT SUGGEST
ANY RIVER FLOODING IN EASTERN NY/WESTERN NEW ENGLAND ASSUMING
WIDESPREAD RAINFALL AMOUNTS REMAIN UNDER 4-5". SO, ALTHOUGH
LOCALIZED PONDING OF WATER IN SOME URBAN/POOR DRAINAGE AREAS,
AND ISOLATED/SCATTERED INSTANCES OF POSSIBLE FLASH FLOODING
WHERE ANY TRAINING HEAVY DOWNPOURS OCCUR, THE THREAT FOR RIVER
FLOODING APPEARS VERY LOW AT THIS TIME.
AVIATION /18Z MONDAY THROUGH SATURDAY/
THROUGH 18Z/TUESDAY...MAINLY VFR CONDITIONS WILL PREVAIL THIS
AFTERNOON OUTSIDE OF SOME ISOLATED SHOWERS/THUNDERSTORMS SEEN
DEVELOPING NEAR AREAS OF HIGHER ELEVATION UNTIL ABOUT 00Z THIS
EVENING. BRIEF DOWNPOURS COULD REDUCE VSBYS TO MVFR ESPECIALLY AT
KGFL, KPOU, AND KPSF, IF THEY OCCUR OVER THE TERMINALS. WITH MODEL
SOUNDINGS SHOWING AMPLE LOW LEVEL MOISTURE, CALMING WINDS, AND
PARTLY CLEAR SKIES, FOG/MIST COULD DEVELOP AT KGFL, KALB, AND KPSF
EARLY TOMORROW MORNING. KGFL AND KPSF COULD SEE FLIGHT CONDITIONS
LOWER TO IFR AND KALB COULD LOWER TO MVFR. BY 08Z-12Z WIDESPREAD
SHOWERS/THUNDERSTORMS MOVE INTO THE REGION FROM THE WEST WITH
PERIODS OF STEADIER RAINFALL. THE HEAVIEST RAINFALL IS EXPECTED TO
OCCUR AFTER 13/14Z. FLIGHT CONDITIONS ACROSS ALL TERMINALS AT THE
ONSET OF THE SHOWERS WILL LIKELY BE MVFR AND BECOME IFR/LIFR WHERE
THERE ARE LOCALLY HEAVY DOWNPOURS THROUGH THE END OF THE TAF PERIOD.
A FEW RUMBLES OF THUNDER ARE ALSO POSSIBLE. WINDS THIS AFTERNOON OUT
OF THE SOUTHWEST 4-8 KT BECOME LIGHT AND/OR CALM OVERNIGHT GENERALLY
LESS THAN 5 KT. TOMORROW BY MID MORNING WINDS PICK UP OUT OF THE
SOUTHEAST 5-10 KT WITH GUSTS UP TO 15 KT BY EARLY AFTERNOON.
OUTLOOK...
TUESDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...TSRA.
WEDNESDAY: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...TSRA.
WEDNESDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...TSRA.
THURSDAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.
FRIDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
DISCUSSION...24/31
AVIATION...05
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