Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
249 AM EDT Tue Aug 13 2019
Valid 12Z Fri Aug 16 2019 - 12Z Tue Aug 20 2019
...Overview and Guidance/Predictability Assessment...
A mean upper trough digs into the Northwest/West with uncertain
amplitude late week as ridging settles over the Southwest and
south-central U.S. This favors some downstream troughing into the
East. Northwest U.S. trough energies eject over the northern
Rockies/Plains then Midwest/Great Lakes/Northeast through the
forecast period, but details remain unclear as models remain
highly run to run inconsistent. Accordingly, The WPC medium range
product suite was mainly derived from a composite blend of the
generally compatable 18 UTC GEFS mean, 12 UTC ECMWF ensemble mean,
and National Blend of Models.
...Weather Highlights/Threats...
A wavy frontal system sags southward through the eastern and
central states later week to stall over the South/Southeast.
Widespread showers and thunderstorms including a threat of local
cell training/runoff issues will focus over the Southeast/Gulf
Coast as deepened moisture pools into the vicinity of the front.
There remains a pre-frontal threat of a few record high
temperatures. The Southwest will also experience hot temperatures
under the upper high/ridge. Northwest/West upper troughing and
system/height fall ejections over the Rockies, north-central U.S.
then Northeast may provide dynamics and instabilities to support
episodes of enhanced thunderstorms/convective clusters with
associated local heavy rainfall/runoff threats.
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