Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Wed May 15 2019
Valid 12Z Sat May 18 2019 - 12Z Wed May 22 2019
...Guidance/Predictability Assessment...
The 06 UTC GFS/FV3 and 00 UTC ECMWF/UKMET/Canadian offer good
forecast clustering this weekend. Despite some common longer term
model similarities, forecast confidence next week remains below
normal due to less than stellar continuity issues. Accordingly,
the WPC product suite primarily was derived from a composite model
solution this weekend before quickly transitioning to more
compatable 06 UTC GEFS mean and 00 UTC ECMWF ensemble mean into
early next week amid growing forecast spread....Guidance
Assessment and Weather Highlights/Threats...
...Weather Highlights and Hazards...
Model and ensemble solutions continue to show above normal
forecast spread with respect to northeastern U.S./Mid-Atlantic
flow through this weekend as a series of potent Canadian upper
systems progress within an energetic northern stream. Favor a
composite.
Upstream, a dynamic mid-upper level trough will lift northeastward
from the southern Rockies to the central then northeastern U.S.
Sat-Tue. This system will spawn surface system/low genesis with
lead moisture inflow and instability providing the foundation for
a threat of heavy convection/rainfall and severe weather as per
SPC. Underneath, a gradually weakening closed low/convection will
weaken over the eastern Gulf of Mexico.
There remains a strong signal that Pacific flow will bring another
round of strong height falls and widespread precipitation/terrain
enhanced snows to the West later this weekend into early-mid next
week before ejecting over the central U.S. Further 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 again early next week along with
renewed unsettled weather/precipitation.
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