Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 AM EDT Sun Jul 14 2019
Valid 12Z Wed Jul 17 2019 - 12Z Sun Jul 21 2019
...Tropical Storm Barry expected to weaken and dissipate prior to
the extended period but will continue to produce areas of heavy
rainfall...
...Overview and Guidance/Predictability Assessment...
...Weather Highlights/Threats...
Tropical Storm Barry made landfall in Louisiana Saturday afternoon
and is forecast to continue to weaken and dissipate by Monday
evening over Missouri/Mid-Mississippi Valley, prior to the start
of the extended forecast. The low will become devoid of tropical
characteristics and will be absorbed in the westerly flow by late
Thursday. Heavier rain associated with the remnants of Barry will
spread from western Tennessee to Ohio and western Pennsylvania by
Wednesday morning; and may very well enhance rainfall across the
Northeast/northern Mid-Atlantic region as the front passes through
Thursday through Friday.
As ridging over southern and central portions of the U.S. remains
in place a vast majority of the Southwest, Southern and Central
Rockies, and the High Plains will remain warmer and drier through
this coming week. Warmer than average temperatures are expected
across these parts and a few locations will have above normal
temperatures that may tie or set new daily high minimum records.
Above normal temperatures with some pockets of plus 10F or greater
anomalies will spread from the Northern Plains to the Northeast
U.S. through Wednesday, with some warmth lingering over the
Northeast into Friday. Portions of the Central Plains and Middle
Mississippi Valley will reach 10 to 15F above average by the end
of the forecast period. Heat indices will be around 105 to 115F,
which will likely require the future issuance of heat advisories.
The Pacific Northwest will trend cooler by Friday with highs 5 to
10F cooler than average.
Across the northern states a quasi-zonal flow pattern will
develop. A series of disturbances will pass through southern
Canada and the northern tier states. Showers and thunderstorms
capable of producing up to 2.25 inches will move through the
Northern Plains, Upper Mississippi Valley and into the Upper Great
Lakes region Wednesday and Thursday. Then, into the Lower Great
Lakes and Northeast Thursday through Friday. There may be periods
where the rainfall amounts, or rates, become excessive as the
frontal boundary stalls over the region.
The pattern across the West will transition as a low approaches
the Pacific Northwest toward the end of the week. This would bring
a period of steadier rainfall with additional terrain enhancement
between the Pacific Northwest coast and the Cascades. The latest
model guidance shows some spread on the strength, timing and
placement of this feature. Again, the ECMWF appeared to have
better support from the ensemble means, and thus was weighted more
heavily in the medium range forecast and maintains previous WPC
forecast continuity.
Campbell
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