Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1214 AM EDT Thu Jun 27 2019
Valid 12Z Sun Jun 30 2019 - 12Z Thu Jul 04 2019
...Overview and Weather Highlights/Threats...
A strong upper high near southern Alaska favors a
positively-tilted trough lingering over the Pacific Northwest and
near to above average heights for the rest of the Lower 48 with
the exception of Texas where an inverted trough will meander. This
typical summertime pattern will feature warm/hot temperatures for
most areas east of the Rockies with scattered mainly afternoon
showers/thunderstorms. Areas in the lower MS Valley/Gulf Coast may
see some enhanced rainfall due to the combination of the upper
trough over Texas and increasing lower-level moisture from the
Gulf. Cooler than average temperatures are expected for much of
the West.
...Guidance/Predictability Assessment...
The deterministic models clustered well together for Sun-Tue
despite some changes over/offshore the Pac NW. The ECMWF has led
the way in this area but now the other models have joined in the
chorus and a blend sufficed. Trended to a 50/50
deterministic/ensemble mean weighting for Wed/Thu via the
ECMWF/Canadian. The GFS runs appeared to be too quick to move the
trough out of WA/OR as can be its bias (even in the FV3 core).
...4th of July Forecast...
Warm to hot temperatures for the central/eastern states with
widespread 80s/90s. Mid 90s are possible in the Southeast where,
combined with dew points in the 70s, will yield heat indices in
the 105-110F range. Best chance of rain/storms will be over the
High Plains/Upper Midwest (near an incoming frontal boundary), the
Ohio Valley (near a wavy stationary front), lower Mississippi
Valley (under the upper trough), and the Southeast. The West will
be dry with near to below average temperatures in the upper 60s
(northern coast), 70s (central/southern coast), 80s/90s
(interior), and low 100s (deserts).
Fracasso
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