Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun May 19 2024
Valid 12Z Sun May 19 2024 – 12Z Tue May 21 2024

…Increasing severe weather and excessive rainfall threats over the
Central U.S. into early next week…

…Sweltering heat continues across South Florida and southern Texas while
expanding into the southern High Plains…

An energetic upper-level pattern will bring a couple rounds of storms to
the central U.S. for Sunday and Monday. On Sunday, moist return flow
following a warm front moving northward through the Plains and ahead of a
dryline over the High Plains will provide more than enough instability to
trigger robust thunderstorm development over the Central Plains.
Increasing upper-level winds will promote supercells with the threat of
large hail and a few tornadoes. Storms are also expected to grow upscale
into one or more organized convective systems, bringing a heightened
threat for potentially widespread, significant damaging winds later Sunday
evening. As such, the Storm Prediction Center has issued a Moderate Risk
of severe weather (level 4/5). Storm chances will shift northeastward into
the Upper Midwest overnight Sunday and into the Great Lakes by Monday
following an initial upper-wave/accompanying surface frontal system. An
amplifying long-wave trough over the West will help to enhance lee
cyclogenesis over the High Plains bringing another chance of storms to the
Central Plains/Missouri Valley by Monday evening. The Storm Prediction
Center has included a Slight Risk (level 2/5) for the threat of some more
damaging winds and large hail, and possibly a tornado. Some locally heavy
downpours will also be possible, particularly from the Central Plains into
the Upper Mississippi Valley Sunday and the Central Plains once again
Monday, with an isolated chance of flash flooding.

The active upper-level pattern will also bring some precipitation chances
to the Northern/Central Rockies and eastern Great Basin over the next
couple of days. Rainfall should generally remain light to moderate, though
some locally heavier storms will be possible especially over Wyoming on
Monday. Some snow is expected for higher mountain elevations. To the east,
an area of low pressure lingering just off the Atlantic coast of the
Southeast with a trailing frontal boundary moving through Florida will
bring more showers and thunderstorms to the area Sunday. Storm chances
will decrease overnight Sunday and into the day Monday from north to south
as the front pushes southward, expected to clear the coast by Tuesday
morning.

Intense Summer-like heat will continue over portions of South Florida and
from southern Texas into the southern High Plains the next couple of days.
Highs in the 90s with high humidity values for areas closer to the coast
will bring heat indices into the 105-110 degree range, with a Heat
Advisory in effect for South Florida Sunday. While not as humid,
temperatures will soar into the 100s further inland into west Texas/the
southern High Plains. Some record-tying/breaking temperatures are
possible. While not as hot, conditions will still be well above average
more broadly across the central/eastern U.S. Highs in 80s will be common,
even into more northerly locations like the Great Lakes and the interior
Northeast. One exception will be where onshore flow keeps things a bit
cooler along the East Coast, with highs in the 60s and 70s expected from
coastal New England south into the Mid-Atlantic and coastal Carolinas.
Highs over the Pacific Northwest/northern Rockies will remain cool Sunday
behind a cold front, with highs in the 50s and 60s. These cooler
temperatures will spread southward into the Great Basin Monday. Highs in
the 80s and 90s are forecast south of the front over the Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat May 18 2024
Valid 12Z Sat May 18 2024 – 12Z Mon May 20 2024

…Unsettled weather with chances for excessive rainfall and severe
thunderstorms continues across the Southeast Saturday…

…Severe weather potential returns to the Central Plains on Sunday…

…Sweltering heat continues across South Florida and southern Texas,
building into the southern High Plains this weekend…

A wet Saturday is in store for the Southeast as an upper-level wave and
associated surface frontal system focused along the Gulf Coast lead to a
broad area of showers and thunderstorms. Rich moisture along and south of
this boundary may lead to some locally heavy downpours, with a Slight Risk
of Excessive Rainfall (level 2/4) in place for portions of southern
Alabama, southwestern Georgia, and the Florida Panhandle. An expected
round of widespread, organized thunderstorms over wet soils from storms
already occurring overnight Friday will lead to the threat of some
scattered instances of flash flooding. Some storms will also carry the
threat for damaging winds and an isolated tornado or two, with a Slight
Risk of severe weather (level 2/5) extending eastward further into
southern Georgia and northern Florida. Moderate to locally heavy rainfall
will be possible elsewhere to the north of the boundary, with a few
additional isolated instances of flash flooding possible. Additional
showers will expand northward into the Mid-Atlantic, and onshore flow
ahead of a system over the Atlantic will bring showers to New England as
well, but these should remain lighter than those over the Southeast. Storm
chances will taper off from west to east for much of the Southeast
overnight Saturday and into early Sunday as the northern part of the
frontal system pushes eastward into the Atlantic. A trailing cold front
will keep storms in the forecast for Florida Sunday.

Some light showers and thunderstorms are expected ahead of another system
moving through the northern Plains into the Upper Midwest/Great Lakes
region Saturday, though these should generally remain light. Then, on
Sunday, additional upper-level energies approaching from the West will
bring a renewed chance of storms more broadly across the Northern/Central
Plains and into the Midwest on Sunday. Moist southerly return flow
following a warm front lifting into the Northern Plains/Midwest and ahead
of a dryline over the High Plains will lead to sufficient instability for
some robust thunderstorm development. The Storm Prediction Center has
introduced an Enhanced Risk of severe weather (level 3/5) for portions of
the Central Plains for the threat of very large hail, damaging winds, and
a few tornadoes. Some locally heavy rainfall will also be possible,
particularly from the Central Plains northeastward into the Upper
Mississippi Valley. Some storms are also expected in the Northern Rockies
as these upper-level energies pass overhead, with some snow possible into
higher mountain elevations.

Intense Summer-like heat will continue over portions of South Florida and
southern Texas this weekend, and expand in coverage into portions of the
southern High Plains. Forecast highs will be in the 90s for Florida with
mid-90s to mid-100s in Texas, potentially record-tying/breaking levels.
When combined with the humidity, heat indices will soar to near 110 in
South Florida, with Heat Advisories in place for Saturday. While not quite
as hot, temperatures will still be well above average more broadly across
much of the country this weekend, particularly from the Central Plains
into the Midwest where highs in the 80s to near 90 will be common. Highs
will also be above average for portions of the West, with 70s and 80s in
the Great Basin/interior California and 90s to low 100s in the Desert
Southeast. More temperate, below average conditions are expected along
much of the East Coast, with 50s and 60s in New England and 60s and 70s
into the Mid-Atlantic/Carolinas. The Pacific Northwest/Northern Rockies
will also be cooler, with highs in the 50s and 60s expected here as well.
Variable temperatures are forecast for the Southeast due to ongoing
storms, with mainly 80s expected.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri May 17 2024
Valid 12Z Fri May 17 2024 – 12Z Sun May 19 2024

…Potentially significant heavy rainfall threat spreads into portions of
southern Mississippi and western Alabama Friday…

…Wet start to the weekend for much of the eastern U.S. as well as the
Northern Rockies/Plains…

…Sweltering heat continues across South Florida and southern Texas into
this weekend…

A broad area of showers and thunderstorms is expected Friday across much
of the eastern U.S., with the chance for moderate to heavy rainfall likely
to focus from the Lower Great Lakes south through the Appalachians into
the Ohio/Tennessee Valleys and to the Gulf Coast. Starting along the Gulf
Coast, another day of potentially significant flash flooding is forecast
along and to the south of a warm front lifting slowly northward across the
region. A Moderate Risk of Excessive Rainfall (level 3/4) has been issued
for portions of southern Mississippi and Alabama where a complex of
organized, heavy downpour-producing storms is forecast over already
saturated soils from storms Thursday night. The location of these
additional storms will likely be influenced by the storms ongoing
overnight, bringing higher uncertainty and highlighting the importance of
remaining aware of the most current forecast. To the north, an active
series of shortwaves will help encourage a couple additional areas of
locally heavier rainfall focused over portions of the central Appalachians
as well as the Lower Ohio/Middle Mississippi Valley. Slight Risks of
Excessive Rainfall (level 2/4) are in place for both locations for the
threat of some scattered instances of flash flooding. Storm chances will
shift southeastward on Saturday, bringing the focus for moderate to heavy
rainfall to the southern Mid-Atlantic south along the coastal Carolinas
into Georgia and lingering along the central Gulf Coast. A Slight Risk of
Excessive Rainfall has been included here for portions of the central Gulf
Coast where higher available moisture is most likely to lead to locally
heavier downpours on top of already saturated conditions from the previous
days’ rainfall. Additional scattered instances of flash flooding remain
possible.

Another frontal system will bring shower and storm chances to the Northern
Rockies/High Plains early Friday and the Northern Plains/Upper-Midwest by
Friday evening. Generally light to moderate rainfall is expected, with the
more moderate rain most likely near the Red River Valley. Cooler
conditions may lead to some snow mixing in through the Northern Rockies,
though no accumulations are expected. Precipitation chances will taper off
into Saturday as the bulk of the system lifts northeastward into Canada.
However, to the southwest, some showers and storms will be possible late
Saturday into early Sunday along a trailing frontal boundary stretching
into the Central Plains.

Conditions will continue to remain unseasonably hot and very much
Summer-like for portions of South Florida and southern Texas into the
weekend. Forecast highs Friday and Saturday range from the low to mid-90s
in South Florida and the mid 90s to mid-100s in southern Texas,
potentially record-tying/breaking temperatures. High humidity will bring
heat indices into the mid- to upper-100s for many locations.
Unfortunately, this pattern looks to continue not only into next week but
into the following week as well. While not quite as hot, temperatures will
also be well-above average and Summer-like across portions of the Northern
and Central Plains Friday, with highs in the mid- to upper 80s forecast.
These temperatures will shift eastward into the Great Lakes region on
Saturday. Variable highs are expected for the rest of the central/eastern
U.S., with above average conditions into the 70s for most of the Northeast
Friday and Saturday, though portions of the Mid-Atlantic will see a cool
down into the 60s Saturday. Slightly below average conditions following a
frontal passage over the Southern Plains and Southeast will continue
Friday with highs mainly in the 70s to low 80s, though a quick warm-up
into the mid-80s to 90s will come Saturday for the Southern Plains. In the
West, conditions will be below average in the Pacific Northwest and along
coastal California, with highs mainly in the 60s. However, above average
conditions are expected into the interior, with highs in the 70s to low
80s in the Great Basin, 80s for the central California valleys, and 90s to
low 100s for the Desert Southwest.