Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
241 AM EDT Sat Apr 13 2019
Valid 12Z Tue Apr 16 2019 - 12Z Sat Apr 20 2019
...Another in a series of dynamic spring storms next week...
...Overview...
Troughing will push through the West early in the week and dive
through the Plains and into the Midwest as ridging comes back to
both coasts temporarily. This supports a strong/robust system
lifting out of the southern Plains into the Great Lakes with a
threat of heavy rain, strong winds, and some wintry weather.
...Guidance Preferences and Predictability Assessment...
Most of the models/ensembles show reasonable clustering to start
the period (Tue) so that a blended/consensus solution sufficed. By
Wed the east-west timing spread remained in place from 24 hrs ago
though it was not quite the dog's breakfast of yesterday as there
has been some contraction westward in the quicker ECMWF members
and eastward in the slower Canadian/GEFS members. However, parent
model and children members (both deterministic and ensemble)
remained separate in each system. Again favored a mostly middle
ground solution very near the 18Z FV3-GFS. As the system should
deepen and turn eastward then northeastward Thu, ECMWF ensemble
members continued to lead the pack with a quicker exit to the
northeast, though the trend has been slower. Opted to discount the
12Z ECMWF ensemble mean in favor of the slower solutions near the
12Z ECMWF/GFS as the low pushes through Michigan Friday. By next
Saturday, the front will push to the coast and perhaps continue
eastward, but with the possibility of sfc wave development that
would slow its eastward progress.
The west will be comparatively quieter, with a weak frontal
passage Wednesday then another late Friday. Consensus positioning
sufficed via the blend preference in the east, which was close to
continuity.
...Weather Highlights/Hazards...
Significant precipitation will again increase starting Wednesday
and continuing into Thursday across the Mississippi/Missouri
Valleys into the Great Lakes as low pressure strengthens over
Kansas. Multi-inch rainfall totals are probable (enhanced in
embedded convection) in some locations of the warm sector and
perhaps to the north/northeast of the low with additional northern
stream support. Temperatures to the north/northwest of the low may
only be marginally cold enough for snow depending on the amount of
cooler air available. Temperatures will largely be within 10-15
degrees of average values for mid-April. The northern/central
Rockies into the northern Plains and Upper Midwest will generally
be cooler than average while the west and east coasts will
generally be milder than average.
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