Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
152 AM EDT Mon Aug 12 2019
Valid 12Z Thu Aug 15 2019 - 12Z Mon Aug 19 2019
...Overview and Guidance/Predictability Assessment...
Upper troughing digs through the Northwest Thu/Fri as ridging
settles over the Southwest and south-central U.S. This favors
downstream troughing into the East. Northwest U.S. trough energy
is expected to eject over the northern Rockies/Plains then
Midwest/Great Lakes Sat-Mon, but details remain uncertain as
models remain quite run-run inconsistent. Accordingly, The WPC
medium range product suite was mainly derived from a blend of the
more capatable 18 UTC GEFS mean, 12 UTC ECMWF ensemble mean, and
National Blend of Models.
...Weather Highlights/Threats...
A wavy lead frontal system will shift southward through the
eastern and central states, stalling out over the South/Southeast
later week. Widespread showers and thunderstorms including a
threat of local cell training/runoff issues are expected to settle
southward from the Mid-Atlantic to focus into the Southeast/Gulf
Coast as deepened Gulf moisture streams into the vicinity of the
front. There remains a threat of excessive heat with some record
pre-frontal high minimum temperatures for portions of Texas and
Florida. The Southwest will also experience hot temperatures
through the period under the upper high/ridge, mitigated locally
by monsoonal convection. Overtop, upper trough amplification over
Northwest/West and potentially robust system/height fall ejections
over Rockies to the north-central U.S. by next weekend would
provide dynamics and instabilities supportive of periods of
enhanced thunderstorms/convective clusters with a threat of heavy
rainfalls.
Tate/Schichtel
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