Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Fri Aug 10 2018

Valid 12Z Mon Aug 13 2018 - 12Z Fri Aug 17 2018

...Pattern Overview and Guidance/Predictability Assessment...

A pair of closed mid-upper lows centered neat the Central
Appalachians and Southern High Plains into early next week will
focus a heavy precipitation threat. Both features are expected to
gradually evolve into open waves with gradual northeastward
migration mid-later week as a potentially ampified new trough/low
digs into the north-central states/Midwest. Have leaned on a more
amplified solution given recent flow history. This is championed
more by the 00 UTC ECMWF and GEFS/ECMWF ensembles.Across the
Desert Southwest/Four Corners region, models advertise a return of
a 594-dm mid-level ridge toward the middle/later part of next week.

Accordingly, the WPC medium range product suite was primarily
derived from a composite blend of the 00 UTC ECMWF and GEFS/ECMWF
ensemble means.


...Weather Highlights and Hazards...

The most focused areas of heavy rainfall will linger near/ahead of
slow to eject closed lows over the Mid-Atlantic/Northeast and back
in the south-central U.S, to be followed by an upstream kicker
moving into the north-central states/Midwest. The main excessive
rainfall threat may further focus along associated/wavy fronts
that will pool depeened moisture and tap instability. Meanwhile,
decent daily chances for monsoonal thunderstorms should develop
over the Desert Southwest and the south-central Great
Basin/Rockies.

Schichtel

WPC medium range 500 mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indexes are found 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