916
FXUS02 KWBC 260658
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
258 AM EDT Sun May 26 2024

Valid 12Z Wed May 29 2024 - 12Z Sun Jun 02 2024


...General Overview...

The upper level pattern across the continental U.S. will be
featured with a trough over the Pacific Northwest, a ridge over the
Northern Plains, and a trough over the Great Lakes for the
beginning of the forecast period Wednesday. Both of these troughs
move rather slowly eastward through the end of the week, 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 cold front, and
this will fuel multiple rounds of heavy rain and thunderstorms
across the Plains for the second half of the work week. The trough
then reaches the Upper Midwest by next weekend while the upper
ridge tries to rebuild across Texas.

...Guidance/Predictability Assessment...

The 00Z model guidance suite maintains good overall agreement on
the synoptic scale for the middle of the week. The main difference
noted is with the UKMET that has been much more progressive with
the Pacific Northwest trough moving inland over the past few runs.
Therefore, the model blend consisted of the CMC/ECMWF/GFS along
with some previous WPC continuity through Thursday. Looking ahead
to next weekend, the 12Z ECMWF appeared much stronger with the
trough crossing the Upper Midwest compared to the model consensus
at the time of fronts/pressures generation. Upon examination of the
machine learning guidance, there was not much support for the more
amplified ECMWF solution, so preference was given to the broader
CMC/GFS/GEFS mean for Saturday and Sunday. Interestingly, the GFS
trended stronger by next Sunday with this same trough, whereas the
ECMWF became less amplified compared to its 12Z run and more in
line with the ML guidance. Ensemble means accounted for about
40-50% of the forecast blend by next weekend.

...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 Wednesday from eastern Colorado to the Texas Gulf coast, and
a Slight Risk area across portions of north-central Texas and into
southwestern Oklahoma on Thursday where MCS activity is most
likely to develop. Additional heavy rain is expected on Friday
across much of Kansas and into Oklahoma and northern Texas with the
overall weather pattern not changing all that much. 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









$$