018
FXUS02 KWBC 200744
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Wed May 20 2026

Valid 12Z Sat May 23 2026 - 12Z Wed May 27 2026

***Heavy rain and thunderstorms expected to continue across eastern
 Texas into the lower Mississippi River valley***

...General Overview...

An active weather pattern will continue to remain in place across
the south-central U.S. going into the upcoming weekend, with
multiple shortwave disturbances and a weak frontal boundary
producing multiple rounds of heavy rain and storms. An upper trough
over the Dakotas should reach the northern Great Lakes by Monday,
with widespread rain likely from the Ohio Valley to the Northeast
ahead of this feature. Looking ahead to early next week, a more
amplified level pattern starts to emerge as a stronger upper trough
and then closed low enter the Pacific Northwest and enveloping more
of the Intermountain West by next Wednesday, and a downstream upper
ridge develops over the Ohio Valley and western Great Lakes.


...Guidance/Predictability Assessment...

The 00Z model guidance suite has come into better overall synoptic
scale agreement compared to the past couple of days, and this
includes a more solidified depiction of the amplifying trough
across the West late in the period. Recent runs of the GFS have
trended more in line with the non-NCEP consensus in contrast to its
more progressive runs yesterday, and forecast confidence has
increased in this pattern change evolving. Across the southern
tier states, the ECMWF and GFS have trended to a closed southern
stream low over Texas and Oklahoma, whereas the CMC portrays more
of an open trough aloft.

The NBM is likely too warm with temperatures across the
northwestern quadrant of the country going into the first half of
next week, so the WPC forecast reflects a colder scenario more in
line with the latest deterministic guidance, and also an increase
in QPF across this same general region given better ascent. The
ensemble means were increased to about 40% by next Wednesday for
fronts and pressures.


...Weather/Hazards Highlights...

Heavy rain will continue to make weather headlines going into the
Memorial Day weekend across much of the south-central U.S. as
multiple mesoscale convective systems develop. These will be in
response to enhanced ascent from an upper trough coupled with a
weak front in the region and plenty of moisture and instability. A
Slight Risk for excessive rainfall will be valid both Saturday and
Sunday from south-central Texas to western Louisiana, where the
potential exists for several inches of rainfall over this time
period over soils that will be becoming increasingly saturated.

Another corridor of moderate to heavy rainfall is expected
across northern portions of the Mid-Atlantic on Saturday, where a
Marginal Risk remains valid, with the potential for some one inch
plus totals within the axis of heaviest rainfall. Elsewhere across
the country, scattered showers and thunderstorms are likely to
develop across portions of the Carolinas this weekend, and some of
these could be locally heavy. More precipitation returns to the
Pacific Northwest to start next week with a cold front moving in
and a building upper level trough.

Lingering cloud cover and rainfall with residual cold air damming
across portions of the Mid-Atlantic and Northeast should continue
to keep temperatures on the cool side on Saturday, with highs
running 10-20 degree below average before a gradual moderation
trend ensues by early next week. It should also be slightly below
average across Texas given the widespread rainfall that is expected
through the weekend. With the upper low developing over the
northwestern U.S., a return to colder conditions is also likely
here going into Tuesday and Wednesday, with some higher elevation
snow likely for portions of the northern Rockies. The greatest
positive anomalies will likely be over the northern Plains and
Upper Midwest with the upper ridge axis Monday through Wednesday,
with readings up to 20 degrees above average.

Hamrick


Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw





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