Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Sat Jun 05 2021
Valid 12Z Tue Jun 08 2021 - 12Z Sat Jun 12 2021
...Much Above Normal Temperatures Continue Into Next Week from the
Northern Rockies/Plains to Northeast....
...Locally Heavy Rainfall Possible Next Week Across Lower/Mid
Mississippi...Tennessee...and Ohio Valleys...
...Overview and Guidance Evaluation/Preferences...
The weather overview for the nation into next week will be the
continuation of much above normal to near record warmth across the
northern tier of U.S., particularly across the northern
Rockies/Plains to Northeast and New England. Uncertain energies to
work into the West/Northwest offers modest rainfall across that
region and a possible stronger/wetter downstream convective focus
for the northern Rockies and north-central U.S. near a wavy front.
Another highlight will be some threat of locally heavy rainfall
next week for the lower to middle Mississippi River Valley that
will gradually spread to the Midwest/Mid-Atlantic during the week.
Latest model guidance is in fairly good agreement with the upper
level pattern over the lower 48 featuring a West Coast cooling
longwave mean trough and a strong Bermuda ridge. Most short range
energy with a ridge embedded upper trough over the south-central
U.S. should lift to the Midwest and slowly lose focusing influence
for unsettled weather through the end of the upcoming work week.
Meanwhile, hot upper ridging gradually builds up over the
west-central U.S. as downstream upper troughing digs over the heat
moderating Northeast and Midwest/Great Lakes. The greatest model
differences are evident mid-later next week with the evolution of
various shortwave troughs moving through the longwave trough over
the eastern Pacific into the western U.S.. Differences have
recently become more of a run continuity issue between 00/06 UTC
guidance and more amplified and less progressive 12/18 UTC
guidance, but the latest differences are smaller than yesterdays.
The WPC medium range product suite was primarily derived from a
GFS/ECMWF/UKMET/Canadian composite model blend days 3/4 (Tue/Wed)
before transitioning to mainly the compatible GEFS/NAEFS/ECMWF
ensemble means by days 6/7.
...Weather Highlights/Hazards...
The interaction of deep/moist flow from the Gulf of Mexico with
weakening surface boundaries up from the western/central Gulf
Coast and lingering upper troughing will continue to provide
episodes of heavy rainfall and possible flash flooding across the
ArkLaTex and Lower/Mid Mississippi River Valley where the greatest
risk area for several inches of rainfall totals exists. Over time
next week, the system is forecast to weaken and lift northward
which will bring numerous to widespread showers and thunderstorms
to portions of the Ohio Valley and Great Lakes regions, which
could produce some locally heavy rainfall. Additional energies
digging into the region may act to further organize activity later
period. Activity will also spread downstream in this pattern into
the Appalachians and Mid-Atlantic as aided with advance of a
temperature moderating backdoor cold front.
Schichtel
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, winter weather outlook probabilities
and heat indices 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/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml