Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
241 AM EDT Mon Jul 15 2019
Valid 12Z Thu Jul 18 2019 - 12Z Mon Jul 22 2019
...Tropical Depression Barry to dissipate prior to this extended
period with remnants to fuel some Northern Mid-Atlantic/Northeast
heavy rains Wednesday/Thursday...
...Overview and Guidance/Predictability Assessment...
...Weather Highlights/Threats...
Tropical moisture from the remnants of Barry will spread across
the northern Mid-Atlantic and Northeast through Thursday as the
leading edge of the front tracks offshore. Areas of localized
heavy rain may increase the threat for flash flooding, especially
in areas of higher terrain and reduced FFG.
A quasi-zonal flow pattern will develop across the northern-tier
of the U.S. Throughout this coming week a series of hard to time
disturbances will pass through southern Canada and through the
northern states. Showers and thunderstorms capable of producing
locally heavy convection/MCS activity will sporadically develop
and propagate within a wavy frontal/baroclinic zone across the
Northern Plains, Upper Mississippi Valley and into the Upper Great
Lakes region, then into the Lower Great Lakes and Northeast. There
will likely be multiple periods where rainfall amounts/or rates
become locally excessive as the moisture and instability pooling
frontal boundary stalls over the region. There is quite a range
for QPF within the global models. With a less than average
confidence on the exact timing and placement of any individual
feature, opted to remain on the near the middle/lower end of the
output with this issuance. The regions with the best chances for
higher precipitation is the Upper Mississippi Valley and Great
Lakes Saturday through Sunday.
Summertime ridging over southern and central portions of the U.S.
will spread over much of the Southwest and Southern and Central
Rockies; keeping temperatures near or above seasonal average. Many
locations are expected to be warmer and drier through this the
extended period. Some locations may tie or set new daily high
minimum records. Heat indices will be around 105 to 115F, which
may lead to some future issuance of heat advisories.
Maintained continuity by keeping a heavier weighting of the 00Z
ECWMF and its ensemble mean, along with the GFS and the GEFS mean.
This blend provided a reasonable compromise for the medium range
forecast.
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