827
FXUS61 KALY 010701
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
301 AM EDT SAT AUG 1 2026
WHAT HAS CHANGED
WHILE THERE REMAINS UNCERTAINTY IN THE EXACT PLACEMENT OF THE
HEAVY RAINFALL AXIS FOR SUNDAY NIGHT INTO MONDAY, THE LATEST
PROBABILISTIC AND ENSEMBLE GUIDANCE INDICATES ONLY A VERY LOW
CHANCE FOR EXCEEDING 2 INCHES IN 24 HOURS ACROSS EASTERN NY AND
WESTERN NEW ENGLAND. THEREFORE, ISOLATED TO SCATTERED FLASH
FLOODING STILL SEEMS TO BE REASONABLE IMPACTS.
KEY MESSAGES
1) THERE IS A MEDIUM TO HIGH CHANCE FOR WIDESPREAD RAIN AND
THUNDERSTORMS ACROSS EASTERN NY AND WESTERN NEW ENGLAND TOMORROW
AFTERNOON THROUGH MONDAY RESULTING IN ISOLATED TO SCATTERED
INSTANCES OF FLASH FLOODING. AREAS MOST AT RISK FOR FLASH
FLOODING WILL BE THOSE THAT RECEIVED HIGH RAINFALL AMOUNTS THIS
PAST WEEK.
DISCUSSION
KEY MESSAGE 1...
AFTER SOME ISOLATED DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS
THIS AFTERNOON, RIDGING BECOMES ESTABLISHED OVER THE WESTERN
ATLANTIC DOWNSTREAM OF A SPLIT FLOW PATTERN. WHILE A BROAD
NORTHERN BRANCH TROUGH TRACKS THROUGH SOUTHERN CANADA, A CUT-
OFF LOW IN THE SOUTHERN BRANCH SLOWLY TRACKS THROUGH THE
MIDWEST. AS WAS DISCUSSED IN THE PREVIOUS DISCUSSION, THERE
REMAINS DISCREPANCIES ON WHETHER THESE TWO FEATURES PHASE OR
NOT TOMORROW INTO TOMORROW NIGHT WHICH WILL DETERMINE WHERE THE
HEAVY RAINFALL AXIS SETS-UP. LATEST TRENDS STILL INDICATE THE
NORTHERN BRANCH WILL HELP FOCUS AND DIRECT THE INITIAL MOISTURE
AXIS AND FORCING FOR ASCENT AROUND THE SAINT LAWRENCE RIVER
VALLEY TOMORROW, SUPPORTING PERIODS OF RAIN AND THUNDERSTORMS.
WHILE THE MOST WIDESPREAD RAIN/STORMS LOOKS TO OCCUR MAINLY
WEST OF EASTERN NY, A FEW WEAK EMBEDDED SHORTWAVES TRACKING
WITHIN THE STRENGTHENING SOUTH TO SOUTHWESTERLY FLOW OVER THE
NORTHEAST WILL LIKELY SUPPORT SCATTERED SHOWERS AND
THUNDERSTORMS. AS THE NORTHERN AND SOUTHERN BRANCH FEATURES
INTERACT, A NEARLY FULL LATITUDE TROUGH DEVELOPS UPSTREAM,
ALLOWING THE WIND REGIME TO TAP INTO THE GULF AND ADVECT A VERY
MOISTURE RICH AIR MASS INTO THE NORTHEAST. IN FACT, PWATS
INCREASE TOWARDS 2" OR WITHIN THE 99TH PERCENTILE OF THE NAEFS
MODEL CLIMATOLOGY FOR THIS TIME OF YEAR. THUS, ANY ISOLATED TO
SCATTERED THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF
PRODUCING HEAVY DOWNPOURS. WITH 20-30KTS OF DEEP LAYER SHEAR, CANNOT
COMPLETELY RULE OUT BRIEF DAMAGING WINDS FROM ANY STORM THAT CAN
GROW UPSCALE; HOWEVER, AMPLE CLOUD COVERAGE IN A HIGHLY MOIST
ENVIRONMENT SHOULD KEEP LAPSE RATES WEAK AND THUS LIMIT INSTABILITY,
KEEPING ANY SEVERE STORMS ISOLATED.
HEADING INTO SUNDAY NIGHT, THE NORTHERN BRANCH IN SOUTHERN
CANADA LOOKS TO SLOW DOWN AND STRENGTHEN, EVEN TAKING ON A
NEGATIVE TILT WHILE THE ONCE CUT-OFF LOW ESCAPES INTO THE TN
VALLEY AND WEAKENS AS IT BECOMES SHEARED OUT. LATEST GUIDANCE
SHOWS A JET STREAK OVER THE NORTHEAST DEVELOPING SUNDAY NIGHT
WITH THE CONTINUED UNIDIRECTIONAL SOUTHERLY WINDS OVER THE
NORTHEAST MAINTAINING A RICH SUPPLY OF WARM AIR AND MOISTURE
ADVECTION. SHOWERS AND EMBEDDED CONVECTION EXPAND EASTWARD
SUNDAY NIGHT INTO EASTERN NY AND WESTERN NEW ENGLAND AHEAD OF
THE APPROACHING PARENT TROUGH; HOWEVER, THERE IS INCREASING
CONSENSUS IN A SECONDARY SFC LOW DEVELOPING IN THE FAVORABLE
EQUATORWARD ENTRANCE REGION OF THE JET STREAK. WHERE THIS
FEATURE DEVELOPS WILL BE KEY AS IT LOOKS TO FOCUS THE
MOISTURE/FORCING LEADING TO A HEAVY RAIN AXIS LATE SUNDAY NIGHT
INTO MONDAY MORNING. THERE REMAINS DISCREPANCIES ON WHERE THIS
AXIS DEVELOPS WITH ONE CLUSTER FAVORING THE MID-HUDSON VALLEY,
NW CT INTO NEW ENGLAND WHILE A SECOND CLUSTER SHOWS IT FURTHER
NORTHWEST INTO MORE OF EASTERN NY.
GIVEN THE RECENT HEAVY/LOCALLY EXTREME RAINFALL MUCH OF
EASTERN NY EXPERIENCED THIS PAST WEEK, MOST SOILS ARE SATURATED
AND RIVERS/STREAMS ARE ELEVATED. 1HR AND 3HR FLASH FLOOD
GUIDANCE VALUES REMAIN LOW RANGING FROM 1 TO 2.5 INCHES SO IF
THESE VALUES ARE EXCEEDING, FLASH FLOODING CONCERNS WILL
INCREASE. GIVEN THE ANTICIPATED HIGHLY MOISTURE RICH
ENVIRONMENT WITH FORECAST SOUNDINGS SHOWING HIGH FREEZING
HEIGHTS 12-13KFT AND TALL/SKINNY CAPE, EFFICIENT WARM RAIN
PROCESSES WILL BE AT PLAY LIKELY SUPPORTING HIGH RAINFALL
RATES, ESPECIALLY WITHIN THE HEAVY RAIN AXIS. HOWEVER, UNLIKE
THE RECENT HEAVY RAIN EVENT, THIS SEEMS TO BE A MORE PROGRESSIVE
PATTERN AS THE TROUGH CONTINUES TO SWING EASTWARD INTO MONDAY.
THUS, EVEN IF HEAVY RAIN CAN PERSIST OVER A GIVEN AREA, IT DOES
NOT LOOK TO LAST MULTIPLE HOURS WHICH LOWERS THE POTENTIAL FOR
WIDESPREAD FLOODING CONCERNS. IN ADDITION, LATEST PROBABILISTIC
GUIDANCE SHOWS JUST A FEW ISOLATED SPOTS WITH VERY LOW VALUES
FOR 24HR RAIN AMOUNTS BETWEEN 8PM SUNDAY AND 8PM MONDAY
EXCEEDING 2 INCHES WITH EVEN THE 90TH PERCENTILE FOR MOST OF
EASTERN NY AND WESTERN NEW ENGLAND UNDER 2 INCHES IN 24HRS.
THEREFORE, WPC MAINTAINED ITS MARGINAL TO SLIGHT RISK FOR
EXCESSIVE RAINFALL IN THE DAY 2 OUTLOOK MESSAGING ISOLATED TO
SCATTERED FLASH FLOODING. THE SLIGHT RISK IS FOCUSED IN THE MID-
HUDSON VALLEY AND NW CT WHERE THE HEAVY RAIN AXIS LOOKS TO SET-
UP BUT GIVEN CONTINUED DISCREPANCIES ON THE EXACT PLACEMENT,
THIS MAY CHANGE IN FUTURE UPDATES. REGARDLESS OF THE SLIGHT RISK
LOCATION, IT IS IMPORTANT TO NOTE AND BE PREPARED FOR THE
POTENTIAL FOR ISOLATED TO SCATTERED FLASH FLOODING SUNDAY NIGHT
INTO MONDAY IN EASTERN NY AND WESTERN NEW ENGLAND. AREAS THAT
WERE HARD HIT WITH HEAVY RAIN THIS PAST WEEK WILL BE MOST
VULNERABLE TO RENEWED FLOODING CONCERNS.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
THROUGH 06Z SUNDAY... CALM WINDS AND MOSTLY CLEAR SKIES WILL ALLOW
RADIATIONAL MIST/FOG TO FORM ACROSS ALL TERMINALS THROUGHOUT THIS
OVERNIGHT PERIOD. KGFL STARTS OFF THIS PERIOD WITH LIFR VIS, WHILE
KALB, KPOU, AND KPSF ARE EXPECTED TO LOWER TO IFR/LIFR THROUGH 12Z.
THE GREATEST VIS RESTRICTIONS ARE EXPECTED AT KGFL AND KPSF, WHILE
KPOU WILL TRANSITION TO PREVAILING LIFR AND KALB SEES ONLY TEMPORARY
IFR VIS/CIGS THROUGH 11Z.
THIS MIST/FOG WILL BURN OFF BY LATE SATURDAY MORNING, RETURNING ALL
TERMINALS TO VFR CONDITIONS BY 14Z. HIGH CLOUDS WILL GRADUALLY FILL
IN AND LOWER THROUGHOUT THE AFTERNOON AND EVENING, WITH A FEW FAIR
WEATHER CUMULUS EXPECTED TO DEVELOP THROUGHOUT THE SAME TIME PERIOD.
CALM TO LIGHT AND VARIABLE WINDS WILL TRANSITION TO SOUTHERLY WINDS
BY THE AFTERNOON, PERSISTING THROUGH THE END OF THE TAF PERIOD.
OUTLOOK...
SUNDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
MONDAY: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...TSRA.
MONDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA.
TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...TSRA.
WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.
THURSDAY: HIGH OPERATIONAL IMPACT. LIKELY SHRA...TSRA.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
DISCUSSION...31
AVIATION...23
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