Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
244 AM EDT Sun Jun 23 2019
Valid 12Z Wed Jun 26 2019 - 12Z Sun Jun 30 2019
...Overview and Guidance/Predictability Assessment...
An upper low is forecast to slowly but steadily move into
Washington and then lift into British Columbia later this week
with building ridging downstream over the High Plains into the
western Great Lakes. Troughing in eastern Canada will likely dip
into the Northeast next weekend as in inverted trough develops
along the central Gulf coast. The latest deterministic models
offered a reasonably well-clustered starting point for the Wed-Fri
period. Thereafter, trended to a blend of the 12Z ECMWF/ECENS mean
and the 18Z GEFS mean which smoothed out timing/amplitude
differences over the lower 48 as the upper high settled into AZ/NM.
...Weather Highlights/Threats...
Upper low will favor cooler than average temperatures in most of
the West (especially Pacific Northwest into the Great
Basin/Intermountain West) and scattered rain/storms with some very
high elevation snow. Temperatures initially 5-15 deg F below
average will moderate back toward typical late-June values by next
weekend as the upper low moves into Canada. Temperatures in the
northern Plains/Upper Midwest will be 5-10 deg F above average
(80s and some low 90s) but with a risk of showers/storms in the
vicinity of a warm front. The Northeast will see a bit cooler
temperatures next weekend as a front slips south/east of the
region. The Southeast and lower MS Valley/Gulf Coast region will
see a daily chance of showers/storms in typical summertime fashion
but that may be enhanced as the upper trough moves westward later
in the week into the weekend.
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