Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
325 PM EDT Wed Jul 24 2019
Valid 12Z Sat Jul 27 2019 - 12Z Wed Jul 31 2019
...Weather Highlights/Threats and Guidance/Predictability
Assessment...
A persistent feature in the upcoming pattern will be a closed high
over the Southwest. Expect daily scattered monsoonal convection
will work around the ridge over the southern Great
Basin/Rockies/High Plains in upper diffluent flow, and pockets of
high heat into interior California and the southern and central
Great Basin into the Southwest.
Mid-level impulses and wavy surface fronts will cross the northern
tier states from the Pacific Northwest eastward to the Great Lakes
and northeast. These will enhance moisture, instability and
showers/storms/MCS activity with a main focus from the n-central
U.S. into the Midwest/Great Lakes.
Underneath, guidance suggests eastern US upper troughing will
gradually deamplify into the weekend, but linger well into next
week as a mid level ridge tends to builds into Florida. A
weakening surface front in Florida to the Gulf of Mexico will be a
focus for heavier convection and rainfall. NHC is monitoring the
northern Gulf of Mexico. Regardless, return warm/moist advection
should allow some activity to move north across the lower to mid
MS Valley and TN Valley and into the Appalachians next week,
lifting inland under increasing influence of southward sagging but
uncertain northern stream systems.
The WPC medium range product suite was primarily derived from a
composite blend of the well clustered guidance from the 06 UTC
GFS/GEFS mean and 00 UTC ECMWF/ECMWF ensemble mean. This maintains
good WPC continuity.
Schichtel
Hazards:
- Heavy rain across portions of the Central Plains, the Middle
Mississippi Valley, the Great Lakes,
the Ohio Valley, and the Upper Mississippi Valley, Sun-Mon, Jul
28-Jul 29.
- Flooding occurring or imminent across portions of the Central
Plains, the Lower Mississippi
Valley, the Northern Plains, the Middle Mississippi Valley, the
Upper Mississippi Valley, and the
Great Lakes.
- Excessive heat across portions of California and the Southwest,
Sat-Sun, Jul 27-Jul 28.
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards 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