505
FXUS61 KALY 272001
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
401 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.
THERE IS INCREASING CONFIDENCE FOR PERIODS OF MODERATE TO HEAVY
TO DEVELOP TOMORROW AFTERNOON LASTING INTO TOMORROW NIGHT. THIS
WILL OCCUR AS OUR PARENT SHORTWAVE CURRENTLY IN THE MIDWEST
ROUNDS THE TOP OF THE EXPANSIVE RIDGE THROUGH THE CENTRAL CONUS
AND AMPLIFIES AS IT TRACKS INTO THE EASTERN GREAT LAKES
TOMORROW. STRONG UPPER LEVEL DIFFLUENCE WILL ALLOW THE SFC LOW
THAT WILL BE IN WESTERN NY TO DEEPEN RESULTING IN A
STRENGTHENING SOUTH-SOUTHEASTERLY LOW-LEVEL JET. THIS WILL LEAD
TO A STRONG AND DEEP MOISTURE FETCH FROM THE GULF AND WESTERN
ATLANTIC WITH PWATS REACHING NEAR 2" RESULTING IN PERIODS OF
MODERATE TO HEAVY RAIN. INITIAL SCATTERED SHOWERS TOMORROW
MORNING REACHING PARTS OF EASTERN NY AND WESTERN NEW ENGLAND
WILL TRANSITION TO MORE ORGANIZED AREAS OF MODERATE TO EVEN
HEAVY RAIN FROM WEST TO EAST BY 15 - 18 UTC CONTINUING INTO THE
OVERNIGHT HOURS AS THE IMPRESSIVE MOISTURE FETCH AHEAD OF THE
LOW CONTINUES TO BE DIRECTED INTO THE NORTHEAST. MEAN CLOUD
LAYER WINDS LOOK TO BE ORIENTED NEARLY PARALLEL TO THE LOW-LEVEL
JET THROUGH 09-12 UTC WEDNESDAY AND WITH FREEZING HEIGHTS 12 -
13KFT AND TALL SKINNY CAPE SOUNDINGS, EFFICIENT WARM RAIN
PROCESSES CAPABLE OF PRODUCING HEAVY DOWNPOURS WILL BE AT PLAY.
THE UNIDIRECTIONAL FLOW ALSO SUGGESTS TRAINING CONVECTION OR
HEAVY RAIN REPEATEDLY IMPACTING A GIVEN AREA, RAISING CONCERNS
FOR FLASH FLOODING. THE OVERALL DYNAMICS WITH THIS EVENT ARE
QUITE IMPRESSIVE FOR JULY WITH THE NAEFS SHOWING HEIGHT
ANOMALIES 3 TO 4 STANDARD DEVIATIONS BELOW NORMAL AS THE PARENT
TROUGH CLOSES OFF INTO WEDNESDAY WITH INTEGRATED WATER VAPOR
TRANSPORT 3-4 STANDARD DEVIATIONS ABOVE NORMAL DUE TO THE HIGH
V-WIND COMPONENT ANOMALIES AND PWATS. LATEST PROBABILISTIC
GUIDANCE FROM THE HREF SHOWS 40 TO 60% CHANCE FOR 1 INCH OF RAIN
FALLING IN 3 HOURS FROM EARLY AFTERNOON TOMORROW THROUGH
TUESDAY NIGHT INCLUDING EVEN 15 TO 30% CHANCE FOR OVER 2 INCHES
IN 3 HOURS. THIS INDICATES MULTIPLE HOURS WHERE HIGH RAINFALL
RATES CAN REACH 1 TO 2 INCHES PER HOUR AT TIMES WITH EVEN
LOCALLY HIGHER AMOUNTS POSSIBLE. THE HIGHEST PROBABILITIES FOR
HIGH RAINFALL RATES RESIDE IN THE EASTERN CATSKILLS DUE TO
FAVORABLE UPSLOPE ENHANCEMENTS.
WHILE OUR RECENT STRETCH OF DRY WEATHER HAS LED TO HIGH FLASH
FLOOD GUIDANCE (FFG) VALUES INCLUDING 2-2.5 INCHES IN 1 HOUR AND 2-3
INCHES IN 3 HRS, TRAINING CONVECTION AND HEAVY RAIN PERSISTING
OVER A GIVEN AREA FOR MULTIPLE HOURS CAN QUICKLY OVERCOME A DRY
GROUND RESULTING IN FLASH FLOODING. IN COLLABORATION WITH WPC
AND NEIGHBORING WFOS, THE HEAVY RAIN SIGNAL WAS STRONG ENOUGH
FOR US TO ISSUE A FLASH FLOOD WATCH FOR AREAS MAINLY SOUTH OF
I-90 FROM 18 UTC TUES TO 00 UTC THURS WITH WPC UPGRADING THE DAY
2 EXCESSIVE RAINFALL OUTLOOK TO A MODERATE RISK (LEVEL 3 OF 4)
TO MESSAGE POTENTIAL FOR NUMEROUS INSTANCES OF FLASH FLOODING.
THERE IS A SLIGHT RISK (LEVEL 2 OF 4) FOR EXCESSIVE RAINFALL FOR
MOST OF THE OTHER PARTS OF THE AREA.
KEY MESSAGE 2...
OUR PARENT CYCLONE BECOMES A VERTICALLY STACKED CLOSES LOW BY
WEDNESDAY AND SLOWS DOWN AS IT SHIFTS INTO EASTERN NY. THE
MOISTURE PLUME SHIFTS INTO NEW ENGLAND BUT CONTINUES TO WRAP
AROUND THE LOW THROUGHOUT THE DAY ON WEDNESDAY SUPPORTING
CONTINUED PERIODS OF STEADY RAIN. NOT ONLY WILL STEADY RAIN
BANDS CONTINUE WITHIN THE DEFORMATION ZONE ON THE NORTH/WEST OF
THE LOW BUT THERE ARE SIGNALS OF A TROWAL DEVELOPING WITH WEAK
INSTABILITY ALOFT SUPPORTING PERIODS OF MODERATE TO HEAVY RAIN.
GIVEN THE HEAVY RAIN FROM TUESDAY INTO TUESDAY NIGHT, SOILS
WILL LIKELY BE SATURATED AND THEREFORE MORE VULNERABLE TO
FLOODING. AT THIS POINT, WE WILL LIKELY TRANSITION MORE TO AREAL
FLOODING VERSUS FLASH FLOODING AS MANY WILL BE RAINING FOR
NEARLY 24 HOURS AT THAT POINT BUT NONETHELESS, ADDITIONAL
FLOODING CONCERNS CONTINUE INTO WEDNESDAY AND OUR FLOOD WATCH
THEREFORE CONTINUES THROUGH 8PM WEDNESDAY. DESPITE THE LONG
DURATION OF THIS RAIN EVENT, THE LATEST MMEFS AND NORTHEAST
RIVER FORECAST CENTER STILL INDICATE NO FLOODING CONCERNS. WRAP
AROUND RAIN CONTINUE INTO WEDNESDAY NIGHT AND EVEN THURSDAY AS
THE LOW WILL BE VERY SLOW TO EXIT INTO NEW ENGLAND. OTHERWISE,
TEMPERATURES WEDNESDAY AND THURSDAY WILL REMAIN BELOW NORMAL
LIKELY STRUGGLING TO RISE OUT OF THE 60S TO LOW 70S GIVEN AMPLE
CLOUD COVERAGE AND RAIN.
AFTER NEARLY THREE DAYS OF RAIN, TOTAL RAINFALL AMOUNTS FROM
TUESDAY AFTERNOON THROUGH THURSDAY RANGE 1.5 TO 3.5 INCHES WITH
THE HIGHEST PROBABILITIES FOR OVER 3 INCHES OF RAIN FROM THE NBM
IN THE EASTERN CATSKILLS, NW CT AND EAST FACING SLOPES OF THE
SOUTHWEST ADIRONDACKS, SOUTHERN GREENS, BERKSHIRES AND TACONICS.
OUR LATEST FORECAST SHOWS 3 TO 5 INCHES IN THESE AREAS WITH
EVEN UP TO 6 INCHES IN THE PEAKS OF THE EASTERN CATSKILLS.
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...FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR CTZ001-013.
NY...FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR NYZ058>061-063>066.
MA...FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR MAZ001-025.
VT...NONE.
DISCUSSION...24/31
AVIATION...53
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