Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Tue May 14 2019
Valid 12Z Fri May 17 2019 - 12Z Tue May 21 2019
...Overview and Weather Highlights/Threats...
Overall. amplified mean troughing aloft will bring a wet period to
a large portion of the western U.S. and Plains states during the
weekend to early next week. Much of the western US to the
northern high Plains will turn colder, with much of the mid-lower
MS Valley eastward turning more summerlike.
Guidance is steadily trending toward resolving the leading strong
trough progressing from the West and Rockies Fri/Sat and in ernest
over the central then east-central states from the weekend into
early next week. This neg-tilt system will spawn surface system
genesis and offers rounds of locally heavy convection/severe
weather as per SPC. Underneath, a gradually weakening closed low
is expected to meander from the northern to eastern Gulf of Mexico
and offer some heavy rain potential for southern Florida.
There is some agreement that upstream flow will bring another
round of strong height falls to the western states this weekend,
continuing inland early week across the Great Basin to the High
Plains. Upstream, there is a still uncertain guidance signal to
develop a deeper low in the eastern Pacific early next week that
offers potential to reach CA and the Great Basin/Southwest by
Tuesday 21 May.
Model and ensemble solutions continue to above normal forecast
spread with respect to downstream northeastern U.S./Mid-Atlantic
flow through the medium range period as a series of potent
Canadian upper systems progress within an energetic northern
stream. These upper systems and surface system reflections have
trended stronger into the weekend. Teleconnections relative to the
negative height anomaly center associated with the West Coast mean
trough then favor modest cyclonic flow aloft into early next week.
...Guidance Assessemnt...
Overall, the latest deterministic models offer better than
expected forecast clustering Fri into Sun morning. The WPC product
suite primarily was derived from a composite model solution during
this period, quickly transitioning to ensemble means early next
week.
Schichtel
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