Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
317 PM EDT Thu May 02 2019
Valid 12Z Sun May 05 2019 - 12Z Thu May 09 2019
...Weather Highlights/Threats...
An area of enhanced rainfall is expected from the northern
Mid-Atlantic to southern New England as the leading low moves
offshore. The trailing cold front will provide a focus for showers
and thunderstorms to develop across the Southeast, Gulf states and
the Southern Plains. Rainfall intensity will likely become heavy
at times, especially over the Southern Plains/Lower Mississippi
Valley.
Ridging aloft will remain anchored over the northeastern Pacific
which will keep drive split flow over the Lower 48 next week. An
unsettling and initially closed southern stream low will work into
California and the Southwest as a series of cooling and
precipitation focusing northern stream systems skirt along the
US/Canadian border. Scattered showers and some convection will
spread across the Great Basin/Rockies. The precipitation is
anticipated to be mostly near the mid-to-high terrain locations.
Some snow may be possible at the highest elevations, but some
valley rain as well.
Additionally, this synoptic setup will be favorable for periods of
organized strong convection with a cell training/excessive
rainfall/runoff threat as a series of hard to time northern and
southern stream impulses eject over the east-central U.S. over top
a building upper ridge over the Deep South. Systems may be primed
to periodically tap deepening moisture and instability pooled by
return Gulf of Mexico inflow into two surface frontal
systems/enhanced baroclinic zones.
...Guidance/Predictability Assessment...
The latest run of guidance is maintaining the overall pattern of a
longwave trough setting up over the West/Southwest and ridging in
over the Southeast; with an improved clustering with the
shortwaves/lows in the Southern Plains, Mid-Atlantic and central
Canada. The WPC medium range product suite was composed from a
blend of the 06Z GFS/00Z ECMWF/00Z UKMET initially with more
weighting of the 06Z GEFS Mean incorporated by the end of the
extended period.
Campbell
Hazards:
- Heavy rain across portions of the Lower Mississippi Valley and
the Southern Plains, Tue-Wed, May 7-May 8.
- Heavy rain across portions of the Middle Mississippi Valley, the
Lower Mississippi Valley, the Southern Plains, the Ohio Valley,
and the Tennessee Valley, Thu, May 9.
- Severe weather across portions of the Central Plains, the Middle
Mississippi Valley, the Upper Mississippi Valley, and the Northern
Plains, Mon, May 6.
- Flooding possible across portions of the Central Plains, the
Lower Mississippi Valley, the Great Lakes, the Middle Mississippi
Valley, the Upper Mississippi Valley, the Southern Plains, and the
Ohio Valley.
- Flooding occurring or imminent across portions of the Central
Plains, the Lower Mississippi Valley, the Northern Plains, the
Great Lakes, the Middle Mississippi Valley, the Upper Mississippi
Valley, the Southern Plains, and the Ohio Valley.
- Flooding likely across portions of the Central Plains, the
Middle Mississippi Valley, the Great Lakes, and the Ohio Valley.
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