Forecast Discussion

343
FXUS61 KBUF 301857
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
257 PM EDT Mon Mar 30 2026

.WHAT HAS CHANGED...
A Flood Watch has been issued for the entire forecast area from
Tuesday morning through Wednesday evening.

The Slight Risk for severe thunderstorms has expanded to cover a
larger portion of Western NY.

&&

.KEY MESSAGES...
1) A significant warming trend will continue through Tuesday.

2) Multiple rounds of convection are expected late tonight through
Tuesday night with an elevated risk for flooding and severe
thunderstorms.

3) Active weather will continue from midweek onwards.

&&

.DISCUSSION...
KEY MESSAGE 1...A significant warming trend will continue
through Tuesday.

A flat ridge building east across the CONUS with strong sfc high
pressure in the western Atlantic will continue the warming trend
through Tuesday. While a mix of 50s and 60s are being observed
this afternoon, temperatures by Tuesday afternoon will reach
well into the 60s for most ares south of Lake Ontario, with
several of the typical warm spots likely reaching the low 70s. A
frontal boundary hung up over Lake Ontario will likely keep the
southern shoreline and areas east of the lake notably cooler in
the 50s. A northeast wind funneling down the valley may keep
areas closer to the St. Lawrence in the 40s and even upper 30s.

A passing wave of low pressure will cause the stalled frontal
boundary to drop southward as a cold front late Tuesday night
through Wednesday morning. This will drop temperatures back towards
seasonal averages through Wednesday night.

KEY MESSAGE 2...Multiple rounds of convection are expected late
tonight through Tuesday night with an elevated risk for flooding and
severe thunderstorms.

A warm frontal boundary moving through the region this afternoon
will stall out in the vicinity of Lake Ontario tonight through
Tuesday. Multiple convective shortwaves and associated waves of
surface low pressure are expected to race east across the Great
Lakes along or just south of this boundary with increased isotherm
packing up against it. With increased broad scale lift on the warm
side of the boundary, several rounds of moderate to heavy showers
and embedded thunderstorms are expected this evening through Tuesday
night. Some of these thunderstorms could be strong to severe, while
the repeated rounds of rain heighten hydrological concerns across
the region.

Flood Watch...

A broad area of surface low pressure extending from the central
Plains through the Great Lakes will draw an anomalously deep plume
of Gulf-based moisture across the Ohio Valley and Northeast tonight
through Tuesday night. Modeled PWATs climb to near 1.25", which if
verified would exceed the daily maximum based on sounding
climatology for BUF. This will be plenty of fuel for showers and
thunderstorms to produce soaking rainfall, though the placement of
the heaviest QPF still remains a bit uncertain. 2-day rainfall
amounts should be a solid 1-2" for most areas south of the St.
Lawrence Valley, though LPMM QPF amounts from hi-res ensembles
heavily suggest several areas seeing rainfall exceeding the 2-3"
range. As of now the heaviest rainfall amounts are forecast west of
the Genesee Valley, where HREF probabilities for local amounts >3"
are highest (30-50%).

Given moist antecedent conditions (this past March being one of the
wettest on record) with several inches of rain possible over the
next 48 hours, have decided to put up a Flood Watch for the entire
region with this update. Regional RFCs are anticipating multiple
area creeks and waterways reaching or exceeding bankfull stage by
Wednesday, with a few slower responding creeks not cresting until
Thursday morning. While overall lower QPF is anticipated east of
Lake Ontario, there remains a substantial SWE across the Tug Hill
and Western Adirondacks which will contribute to significant runoff
across the Black River basin.

Severe thunderstorms potential...

A strong 40-55kt southwesterly LLJ will move into the region tonight
and a brief lull Tuesday morning notwithstanding, remain overhead
through Tuesday evening. This will cause 0-6km bulk shear values to
exceed 40kts with 0-1km and 0-3km layer SRH values to increase to
over 250m2/s2. The main limiting factor in this setup still appears
to be CAPE, especially tonight through Tuesday morning. There will
likely still be enough elevated instability present to support
scattered thunderstorms during this timeframe, though these will
struggle to become surface-based especially given the diurnal
timing. The primary timeframe of concern is later Tuesday afternoon
through Tuesday evening, particularly south of I-90 where MLCAPE
values will manage to build to around 1000J/kg. While not overly
impressive, given the overall dynamics of the system and the fact
that the atmosphere will likely have time to recover after the
overnight/early morning convection....This continues to look like a
classic high shear, low CAPE severe weather setup. If recovery
between rounds of convection is sufficient and there is more
clearing of skies, CAPE could build to be even higher than
currently forecast.

SPC`s latest Day 2 Outlook has expanded the previous Slight Risk to
encompass Western NY from Niagara Falls to Batavia and southward to
the Southern Tier and the upper Genesee Valley, with the Marginal
Risk being maintained elsewhere. As indicated by their 2% "hatched"
probabilities, given the very strong low-level wind profiles, if
stronger storms do manage to form the risk for tornadoes could be
elevated, with a stronger tornado not out of the question.

KEY MESSAGE 3...Active weather will continue from midweek onwards.

A broad area of surface low pressure will cross the eastern Great
Lakes Tuesday night, forcing the stalled frontal boundary over the
region southward as a cold front. This boundary will run up against
the strong sfc high still anchored in the western Atlantic and
likely stall out somewhere over the Ohio Valley and Pennsylvania.
There remains uncertainty in how quickly the front manages to move
through, as well as its position once it stalls to the south.
Temperature and precipitation chances Wednesday and Wednesday night,
especially south of Lake Ontario, will heavily depend on theses
details. Strong Canadian high pressure building across northern
Ontario and Quebec will be attempting to both dry out the area north
of the boundary while advecting cooler air southward. There is a low
chance that this colder air causes a bit of wet snow to fall across
portions of the region Wednesday night into early Thursday.

Moving later into the week, a few Pacific-based shortwave troughs
will shift across the CONUS and cause this boundary to return back
northward. This will again cause temperatures to see another
significant warming trend, though also reintroduce deeper Gulf-based
moisture to the easter Great Lakes. Several opportunities for rain
and thunderstorms can be expected right through this weekend as
these systems move through.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of early afternoon flight conditions remain VFR regionwide under
varying amounts of mainly mid and high cloud cover...with only a few
spotty light showers crossing the Southern Tier. As we push through
the rest of the day and tonight a warm front will extend eastward
across our region...with additional scattered light showers south of
Lake Ontario late this afternoon becoming more widespread from south
to north and becoming moderate in intensity tonight...with a few
widely scattered thunderstorms also becoming possible late tonight
south of Lake Ontario as some weak elevated instability develops.

As all this occurs...deepening moisture attendant to the burgeoning
warm front and the increasingly widespread showers will result in
ceilings lowering to MVFR/spotty IFR across the lower elevations and
IFR across the higher terrain tonight...with any heavier showers or
storms also potentially producing some MVFR visibilities. Meanwhile
still-breezy conditions early this afternoon will give way to
diminishing surface winds late this afternoon/early this evening.
LLWS will then redevelop late this evening and overnight across the
lower elevations south of Lake Ontario as a 30-35 knot southwesterly
low level jet strengthens to 50-60 knots...with the greatest LLWS
focused along a rough KDKK-KBUF/KIAG-KROC corridor.

On Tuesday the warm front will stall out along or just south of the
south shore of Lake Ontario. To its north...a cool moist NE flow
will maintain IFR/LIFR conditions through the day...along with
periodic showers and perhaps a couple rumbles of thunder. To the
south of the boundary...ceilings will mainly range from MVFR to low-
end VFR with occasional showers and scattered thunderstorms...with
any heavier showers/storms potentially producing brief/localized
reductions to IFR/MVFR. While any thunderstorms should remain mainly
elevated in nature during the morning...increasing surface-based
instability during the midday/afternoon may allow for some stronger
surface-based thunderstorms to develop across portions of western
New York and the Finger Lakes...with the greatest risk of these
found across the Southern Tier and interior of the Finger Lakes.
Should the latter occur...the main threat from these would be for
localized strong wind gusts to 50 knots...though there will also be
a lower secondary risk of large hail and isolated tornadoes.
Otherwise...LLWS across WNY will relax again during the morning as
the LLJ aloft weakens...and daytime mixing leads to breezy
conditions redeveloping again at the surface.

Outlook...

Tuesday night...IFR/MVFR with widespread rain and scattered
thunderstorms...a few of which could be strong in the evening south
of Lake Ontario.

Wednesday...Morning showers south of Lake Ontario gradually
diminishing...though probably not ending completely across the
Southern Tier. MVFR/IFR ceilings persisting from KBUF-KROC
southward...while improving to MVFR/VFR further north.

Thursday and Friday...Periods of MVFR/IFR in showers, with the
chance of a few thunderstorms at times. A wintry mix will be
possible Thursday across the North Country and Saint Lawrence
Valley.

Saturday...VFR/MVFR with scattered to numerous showers and possibly
a couple isolated thunderstorms.

&&

.MARINE...
Southwesterly winds of around 15 knots (and locally to 15 to 20
knots) on Lake Erie and Lake Ontario will linger through late this
afternoon...before dropping off again through early this evening.
These will continue to produce choppy conditions through late this
afternoon...though winds and waves will remain below advisory levels
in most areas.

A warm front will then extend eastward across the Lower Lakes region
tonight...then will stall out along or just south of the south shore
of Lake Ontario Tuesday. This will result in southwesterly winds
prevailing across Lake Erie...with southwesterlies on Lake Ontario
this evening turning easterly/northeasterly later tonight on
Tuesday. Another period of moderately brisk winds (to 15-20 knots)
will be possible on Lake Erie later tonight into Tuesday morning...
and on western Lake Ontario Tuesday afternoon and evening. While
this will again produce fairly choppy conditions in the above
areas...at this point conditions are not expected to reach Small
Craft Advisory criteria.

Low pressure will then either pass over or just to the north of Lake
Ontario Tuesday night...while pushing its trailing cold front
southward across our region. Owing to the closer track of the low...
the southwesterly winds out ahead of the front do not look to be
quite as strong as they did previously...with any moderately brisk
conditions now looking to be mainly confined to Lake Erie and not
quite reaching to advisory levels. In the wake of the front...winds
will then veer to north and northeast later Tuesday night and
Wednesday...while likely remaining mostly below advisory levels.
Somewhat better chances for SCA-worthy conditions may then develop
Wednesday night into Thursday...as the northeasterly flow
strengthens out ahead of another wave of low pressure making its way
from the central Plains to the Upper Midwest.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Flood Watch from Tuesday morning through Wednesday evening for
     NYZ001>008-010>014-019>021-085.
MARINE...None.

&&

$$

DISCUSSION...PP
AVIATION...JJR
MARINE...JJR

NWS BUF Office Area Forecast Discussion