Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
134 AM EDT Sat Aug 10 2019
Valid 12Z Tue Aug 13 2019 - 12Z Sat Aug 17 2019
...Overview and Guidance/Predictability Assessment...
It is still expected that generally quasi-zonal flow will prevail
early next week over the CONUS, with embedded shortwaves tracking
through and some indication of troughing along the West Coast. By
midweek, more amplified flow begins rebuilding as a deeper trough
digs into the Northwest and ridging centered in the Southern
Plains strengthens by Thu/Fri. This would likely lead to troughing
downstream in the eastern U.S. Deterministic guidance continues to
offer significant timing differences with embedded systems within
the flow, but the 12 UTC GEFS/ECMWF ensemble means remain in
pretty good alignment, so this multi-model blend was used days 3-7
along with the National Blend of Models. WPC product suite
continuity was well maintained with this solution despite marginal
system predictability.
...Weather Highlights/Threats...
Widespread rain and thunderstorms are expected around an early to
midweek Great Lakes/Ohio Valley to Northeast low pressure system
ahead of a main trackable shortwave. Gulf moisture flowing into
the vicinity of the associated front that pushes to the South and
especially the Southeast will lead to scattered showers and
thunderstorms including potential for some cell training and
related runoff issues. Upstream, impulse and upper jet energies
working out form the unsettling western U.S. upper trough later
next week will also support some organized convective developments
out into the north-central U.S. Temperature-wise, pre-frontal
above average temperatures are forecast in the southern tier
underneath the upper high that will lead to the likelihood of
excessive heat and widespread record high minimum temperatures.
Meanwhile the northwestern and north-central to Northeast CONUS
will generally have below average temperatures.
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