Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
442 PM EDT Fri Jul 26 2019
Valid 12Z Mon Jul 29 2019 - 12Z Fri Aug 2 2019
...Overview and Guidance/Predictability Assessment...
An upper high will meander around the Four Corners region as
troughing digs into the eastern states as well as the Pacific
Northwest. The models/ensembles largely agree for the first few
days of the period (Mon into Wed) and a general model blend
sufficed. For mid-later next week, recent GFS runs have been the
most progressive of guidance aloft with trough energy ejection
from the northeast Pacific inland over Canada and into the U.S.
northern tier. The ECMWF and ECMWF ensemble mean have been the
least progressive, holding most troughing offshore. WPC continuity
has been favoring the less progressive solution, but prior support
for from the GEFS, Canadian and UKMET is less now. Opted to blend
the 00 UTC ECMWF/ECMWF ensemble mean with the now more progressive
06 UTC GEFS mean to address timing uncertainty and trends. This
acts to still maintains good WPC continuity, albeit with a less
certain flow pattern at these longer time frames.
...Weather Highlights/Threats...
Hot temperatures in the Southwest will moderate as monsoonal
moisture increases and clouds/showers/storms expand in coverage.
Convective rainfall including some locally heavier
downpours/runoff issues will focus along and ahead of the frontal
boundaries from the Great Lakes and MS/OH Valley early in the week
into the Northeast/Appalachia and then the Mid-Atlantic toward the
middle and end of the week. Florida may see an enhanced period of
rainfall with a dissipating surface boundary over the central
peninsula into early next week.
Fracasso/Schichtel
Hazards:
- Flooding possible across portions of the Upper Mississippi
Valley and the Northern Plains.
- Flooding occurring or imminent across portions of the Lower
Mississippi Valley, the Great Lakes,
and the Northern Plains.
- Excessive heat across portions of California, Mon, Jul 29.
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