574
FXUS02 KWNH 270658
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 AM EDT Mon May 27 2024

Valid 12Z Thu May 30 2024 - 12Z Mon Jun 03 2024


...General Overview...

The upper level pattern across the continental U.S. will be
featured with a trough over the Northern Rockies, a ridge over the
Upper Midwest, and a trough over the Northeast U.S. for the
beginning of the forecast period Thursday. Both of these troughs
move rather slowly eastward through Saturday, while the southern
tier states have more zonal flow aloft. The trough crossing the
Rockies will be accompanied with a surge of moisture from the Gulf
of Mexico ahead of an approaching frontal boundary, and this will
fuel multiple rounds of heavy rain and thunderstorms from northern
Texas to the central Plains for the second half of the work week.
The trough then reaches the Upper Midwest by next weekend and then
lifts northward into Canada, while the upper ridge rebuilds across
Texas late in the forecast period.

...Guidance/Predictability Assessment...

The 00Z model guidance suite is in good overall synoptic scale
agreement for Thursday and Friday, even though the UKMET is still a
little more progressive with the trough exiting the Rockies to the
Northern Plains. The UKMET is now closer to the consensus compared
to previous runs when it was much faster than the other guidance.
The GFS is now slower with the passage of the other trough across
the East Coast compared to the consensus, but matches up pretty
well elsewhere through Friday. A multi-deterministic model blend,
with slightly less weighting to the UKMET, sufficed as a starting
point in the forecast process through the end of the week.

Looking ahead to next weekend, the GFS becomes stronger with a
second trough developing across the north-central U.S. that does
not currently have much support from the other guidance, and this
remains the case going into next Monday. The CMC is the faster
solution with the next trough approaching the Pacific Northwest by
Monday. There is good overall agreement that the upper ridge will
build back across Texas by this time as well. Ensemble means
accounted for 30-50% of the forecast blend by Sunday-Monday.

...Weather/Hazards Highlights...

Numerous showers and thunderstorms are likely across much of the
central and southern Plains going into the second half of the work
week as a warm front lifts up from the western Gulf and advects
copious moisture northward. This will also be in tandem with
increasing lift afforded by an incoming upper trough from the
Rockies. A broad Marginal Risk area is planned for the new Day 4
period Thursday from central Texas to the eastern Dakota, with a
Slight Risk remaining in place over north-central Texas and into
southern Oklahoma, where MCS activity is most likely to develop.
Additional heavy rain is expected on Friday across many of these
same areas with the overall weather pattern not changing all that
much, with a broad Day 5 Marginal Risk area planned from northern
Texas to the Upper Midwest. There will likely be the need for a
Slight Risk area during this time in future updates, but the
differences in QPF maxima among the guidance preclude having any
Slights at this time. Some strong to severe thunderstorms are also
likely. The potential exists for 3-5 inches of rainfall through
late Friday for some of these areas that get repeated rounds of
convection.

Hot and humid conditions are expected to continue across much of
the Gulf Coast region, including the Florida Peninsula, going into
the end of the week, but a few degrees cooler compared to what is
happening now. This will equate to highs in the upper 80s to middle
90s for these areas, and low-mid 100s for interior portions of
southern Texas. The opposite will hold true from the Great Lakes to
the Mid-Atlantic and Northeast as a relatively strong cold front
heralds the arrival of a high quality airmass with pleasantly cool
conditions and lower humidity to close out the week. There will
likely be some showers across the northeastern quadrant of the
nation in conjunction with the trough/upper low that passes
through the region. Cooler weather is also expected from the
Pacific Northwest to the Northern Rockies courtesy of the upper
trough moving overhead, and then a return to warmer conditions for
much of the Western U.S. by next Sunday.

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 (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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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