301
FXUS61 KALY 311749
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
149 PM EDT Thu Jul 31 2025

.SYNOPSIS...
Much cooler today with periods of steady rain. As a disturbance
rides along a stalled bounday, periods of moderate to heavy rain
are expected in the eastern Catskills, mid-Hudson Valley and
Litchfield County through this evening and, if heavy rain
persists, can result in isolated to scattered flash flooding.
A stretch of seasonably cool and comfortable weather ensues
tomorrow and Saturday before temperatures trend warmer through
early next week.

&&

.DISCUSSION...
Key Message

 - Heavy rainfall rates reaching up to 1 to 2 inches per hour
   this afternoon into this evening in the eastern Catskills,
   mid-Hudson Valley, and Litchfield County, CT, can result in
   isolated to scattered flash flooding, especially if heavy
   rain persists over a given area. A Flood Watch will be in
   effect for these areas from 2pm today to 8am Friday.

Widespread rainfall continues to stream eastward across much of
eastern NY and western New England this afternoon as surface anafront
has already settled well to our south across NJ/PA with northerly
winds in its wake. We have already hit our high temperature for
the day and thanks to wet-bulbing processes, will continue to
stay in the 60s the rest of the day. Latest Advanced Layer
Precipitable Water (ALPW) satellite imagery shows two sources of
rich moisture streaming into the Northeast with one plume
stemming from the eastern Pacific and a second plume from the
Southeast impinging into the mid-Atlanitc/southern New England.
Where these two sources converge will be the focus for the
heaviest rainfall rates and flash flooding concerns and latest
high res guidance points to areas mainly south of our area in
the NJ/NYC metro which remain in the warm sector and have higher
available instability.

However, the strong temperature gradient over southeastern NY
(60s in the eastern Catskills/mid-Hudosn Valley and mid to upper
70s in NW CT to 80s in NYC) has supported strong mid-level
FGEN. As a shortwave in the Ohio Valley rides along the
boundary this afternoon into this evening and encounters
enhanced forcing for ascent from a 125 - 140kt jet positioned
in eastern Quebec, the FGEN in the 850 - 700hPa layer likely
tightens supporting periods of moderate to even heavy rain.
While stratiform rain will continue over much eastern NY and
western New England as we remain on the "cool side" of the
boundary, guidance still suggests that the leading edge of the
stratiform rain over the mid- Hudson Valley, NW CT, and the
eastern Catskills will feature higher rainfall rates reaching
1-2 inches per hour. As a sfc low develops in the mid-Atlantic
and tracks across NJ this afternoon into this evening, the band
of stratiform rain over Upstate NY looks to pivot from northeast
to southwest. This could support heavy rainfall persisting or
training over parts of the mid- Hudson Valley, eastern Catskills,
and Litchfield County, CT, especially given slightly more
instability available in Dutchess/Litchfield and where forward
propagating corfidi vectors remain parallel to the mean cloud
layer flow.

The latest HREF shows a 50-70% chance for rainfall rates at or
above 1 inch in 3 hours from 18 UTC Thurs - 03 UTC Fri where we
have the Flood Watch with even a 10% chance for at or above 3
inches in 3 hours. However, the highest probabilities for
higher rainfall rates/amounts remain to our south in NJ/NYC area
where the ERO moderate risk was expanded. Latest Flash Flood
Guidance from the NERFC still shows 2 - 3 inches in 1 hour and 3
- 3.5 inches in 3 hours (slightly lower over the eastern
Catskills) for these areas so it will take heavy rain persisting
over a given area before flooding occurs. Latest total rainfall
amounts still ranges from 1 to 3 inches with locally up to 3 to
5 inches not ruled out where heavy rain trains/persist, per
latest 24 hour max and LPMM ensemble guidance from the HREF. A
sharp cut-off in rainfall totals expected north of the I-90
corridor with near or under 0.25 inches in the southern/western
Adirondacks and Upper Hudson Valley. The heaviest rain winds
down by 03 - 06 UTC with lingering shows exiting from northwest
to southeast by 12 UTC Friday.

A stretch of dry and seasonably cool weather ensues tomorrow
through Saturday as Canadian high pressure builds over the
Northeast supporting low humidity with abundant sunshine on
Saturday. Friday night and Saturday night temperatures will be
cooler than normal falling into the 40s and 50s thanks to ideal
radiational cooling. We trend warmer Sunday through the middle
of next week with daytime highs back in the 70s and 80s and
higher humidity returning.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Through 18z Friday...IFR conditions at all TAF sites except KGFL.
IFR conditions expected at KALB/KPOU/KPSF into the overnight as
periods of rain forecast to continue.  Included a tempo for thunder
for a couple of hours at KPSF and KPOU due to stronger convective
showers moving across those sites this afternoon. MVFR/IFR
conditions will continue all sites except KGFL through 12z Friday as
rain gradually tapers off overnight. Winds will be northwest to
north at 5 to 15kt this afternoon and evening becoming north to
northeast at 5 to 10kt overnight and continuing Friday morning.

Outlook...

Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
Higher rainfall rates up to 1 to 2 inches per hour can result
in flooding in low-lying, poor drainage, and urban areas this
afternoon into this evening but antecedent dry conditions means
it will take heavy rain persisting over a given area before
isolated to scattered flash flooding can develop. Neither the
latest MMEFS guidance from both the GEFS and NAEFS nor the
Northeast RFC forecasts show river flooding expected through
tomorrow morning. A Flood Watch will be in effect from 2 PM this
afternoon to 8 AM Friday.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ001-013.
     Flood Watch through Friday morning for CTZ001-013.
NY...Flood Watch through Friday morning for NYZ063>066.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Rathbun/Speciale
DISCUSSION...Speciale
AVIATION...SND
HYDROLOGY...Rathbun/Speciale