Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
243 AM EDT Wed May 01 2019
Valid 12Z Sat May 04 2019 - 12Z Wed May 08 2019
...Guidance/Predictability Assessment ...
WPC medium range surface/fronts and 500 mb progs were mainly
composed from a composite of compatable GFS/ECMWF/UKMET/Canadian
mid-larger scale mass field guidance this weekend. Transitioned to
an ensemble mean based forecast early-mid next week amid growing
forecast spread and uncertainty. This blended solution acts to
mitigate embedded smaller scale impulse timing and convection
genesis uncertainties and maintains good overall WPC continuity.
The WPC forecast did favor ECMWF/ECMWF ensembles precipitation
that better fit the flow in showing more southward convective
tendancies into deepening moisture.
...Weather Highlights/Threats...
A slow moving and wavy trailing front will pool moisture to fuel a
risk of locally heavy rains/thunderstorms with cell training and a
local runoff issue focus from the Lower Mississippi Valley to the
Mid-Atlantic this weekend.
Upstream, closed low/trough energy and height falls are expected
to move inland into CA/Southwest early next week in the split
southern stream. This may support scattered CA to Great
Basin/Rockies convection. Flow progression may then renew lead
convective focus downstream over the south-central U.S.
Meanwhile, northern stream systems will meanwhile progress over
southern Canada and effect the U.S. northern tier. These would
support precipitation/convection ahead of a cooling main closed
low/trough and lead weather focusing surface frontal systems. This
amplified main system will track from s-central Canada this
weekend to eastern Canada early next week. A stalling trailing
front underneath into will periodically focus activity over the
northern Rockies, central Plains, and from the Midwest to the
Northeast. This may include some May snows for the Rockies and
from northern Minnesota to the Upper Great Lakes.
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