Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
104 AM EDT Tue Jun 18 2019
Valid 12Z Fri Jun 21 2019 - 12Z Tue Jun 25 2019
...Weather Highlights/Threats...
Several rounds of showers and thunderstorms are possible from the
southern Plains across the MS Valley, Oh Valley and Great Lakes.
Pockets of severe convection and heavy rainfall are possible.
Rainfall Thu night and Fri over the northeast departs and
conditions improve over the weekend.
The upper trough over the northern Rockies and Plains brings much
colder than normal temperatures across the regions days 3 and 4,
spreading south into CO day 5, while moderating over the northern
Rockies. With the upper low departing CO and WY moderate back
towards normal early next week. The new trough in the Pacific
northwest to the Great Basin brings more below normal temperatures
to the region early next week, extending down into the southwest.
The continued high heights across the southern mid Atlantic and
southeast coastal areas brings a prolonged period of above normal
temperatures.
...Guidance/Predictability Assessment...
The days 4-7 forecasts were derived from a blend of the 12z ECMWF
Ensemble Mean and 18z GEFS Mean, with less weighting on the 12z
operational ECMWF and 18z GFS.
The 12z ECMWF Ensemble Mean and 18z GEFS Mean continuity to show
better than average run to run continuity and overlap/agreement
with each other, in contrast to the significant run to run changes
in the 18z GFS and 12z ECMWF.
The overall pattern remains in place to have an initial northern
Plains upper trough and embedded closed low that eventually moves
up into southern Canada. A succeeding upper trough develops in the
Pacific northwest and then expands inland into the Rockies and
Great Basin early next week.
The departure of the cyclone off the New England coast Fri is
followed by rising heights and approach of a deep layer ridge over
the weekend into early next week.
Petersen
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