Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
344 PM EDT Sun Jun 25 2023

Valid 00Z Mon Jun 26 2023 - 00Z Wed Jun 28 2023

...Widespread showers and storms Monday for the East Coast with the risk
of flash flooding and severe weather in the Mid-Atlantic...

...Oppressive heat wave shows no signs of letting up across portions of
the south-central U.S....

...Locally heavy rainfall possible for northern portions of the West...

A lingering frontal boundary across the interior Northeast/New England and
a frontal system in the Midwest will continue to lead to showers and
storms overnight Sunday into early Monday. Widespread showers and storms
are expected along the East Coast Monday as the frontal system approaches
from the west. Favorable upper-level dynamics for mid-summer and rich
moisture flowing northward ahead of the system will lead to the risk of
locally heavy rainfall totals and some potentially intense rainfall rates.
A Slight Risk of Excessive Rainfall (level 2/4) is in effect for portions
of the Mid-Atlantic where conditions appear most favorable for some
isolated to scattered instances of flash flooding. In addition, the Storm
Prediction Center has highlighted the region for an Enhanced Risk of
severe weather (level 3/5). Robust daytime heating will lead to strong
CAPE and vigorous storm development, while sufficient upper-level flow
with an approaching trough will provide enough deep-layer shear for storm
organization. Clusters/lines of storms will be most likely with damaging
winds the main threat, though some hail and a tornado are also possible.
Highs on Monday will range from the low 80s in the Northeast to the low
90s to the South ahead of the system, with highs falling around 5-10
degrees on Tuesday after the system moves through. Much below average
temperatures will continue north of the lingering frontal boundary in
northern New England, where highs will only be in the 60s and low 70s.
Cooler temperatures have also followed the frontal passage in the Great
Lakes region, with highs in the 60s and 70s forecast the next couple of
days.

The oppressive heat wave in the south-central U.S. shows no signs of
letting up as a stagnant upper-level ridge remains in place. Widespread
heat-related advisories are in effect for southern Arizona and New Mexico
and across most of Texas as temperatures soar once again into the 100s. A
duality remains in place with the driver of the dangerous heat-related
impacts, with higher air temperatures in the deserts and west Texas and
lower air temperatures but higher humidity and heat indices in east Texas,
both contributing to a significant risk of heat-related illnesses,
especially as the longevity of the heat wave increases. Some daily
record-tying/breaking high temperatures are once again possible both days.
In addition, overnight lows will also be abnormally warm, at
record-tying/breaking levels, providing little to no relief from the heat
overnight. Elsewhere in the region, a weak cold front will bring down
temperatures a bit Monday for the central Plains and Middle/Lower
Mississippi Valley before the heat wave begins to expand across the region
this week. Gusty winds and very dry antecedent conditions have also lead
to a Critical Risk of Fire Weather for portions of northeastern Arizona
and northwestern New Mexico Monday.

Meanwhile, lift ahead of an upper-level trough over the West Coast will
spark daily shower and thunderstorm chances from the northern Great basin
into the northern Rockies/adjacent High Plains Monday and spread into the
northern Plains on Tuesday. Lingering high surface moisture east of the
Rockies will lead to some locally heavy rainfall totals. Highs will
generally be well below average across much of the West, with 60s and low
70s along the West Coast, mid-80s for the central California Valleys, and
70s to low 80s across much of the Great Basin and into the northern
Rockies. Highs will be closer to/above average in the Pacific Northwest,
with 70s in the urban I-5 corridor and mid- to upper 80s in the interior. 


Putnam


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php