Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
408 PM EDT Thu Apr 11 2019
Valid 12Z Sun Apr 14 2019 - 12Z Thu Apr 18 2019
...Two major spring storms offer a heavy rainfall/flooding threat
from the mid-lower Mississippi Valley to the Ohio Valley this
weekend and again through next midweek along with a risk of severe
weather over the South...
...Weather Highlights/Hazards and Guidance/Predictability
Assessment...
A highly dynamic mid-upper trough/height falls and coupled upper
jet support across the southern Plains through the mid-lower MS/OH
Valleys this weekend, bringing widespread heavy rains with
potential of excessive rainfall and flash flooding as deep
moisture (1.5+ S.D. above normal) is pulled inland from the Gulf
of Mexico. There is also a risk of severe warm sector convection
over the South as per SPC. The potent low and enhanced but
progressive precipittaion will track over the Northeast Monday
where there is some threat of onset northern New England snow/ice.
There will also be rains/convection along and ahead of a trailing
cold front moving across the South, East and offshore into the
Gulf of Mexico and western Atlantic. The 00 UTC
GFS/ECMWF/GEFS/ECMWF ensemble mean solutions are well clustered in
a pattern with above normal predictability.
Meanwhile upstream, models and ensembles still agree to bring
potent mid-upper level troughing/ample height falls/frontal
precipitation into the West Coast Sunday.
The southern stream upper trough is reinforced over the Great
Basin and Rockies Monday/Tuesday to emerge over the Plains midweek
then east-central U.S. by Thursday. Height falls should induce
Plains cyclogenesis with a renewed return flow of deepening Gulf
moisture and ascent leading to enhanced rainfall in eastern OK/TX
extending downstream into the mid-lower MS to Ohio Valleys. Given
a similar cyclone track/intensity and support profile/upper level
trough track, similar areas hit by rain this weekend are expected
to receive a repeat heavy rain and strong to severe threat. The 00
UTC GFS/ECMWF/GEFS/ECMWF ensemble mean solutions are well
clustered in a pattern with much above normal predictability
considering this longer timeframe.
Schichtel
Hazards:
- Heavy precipitation across portions of the Pacific Northwest and
the Northern Great Basin, Sun-Tue, Apr 14-Apr 16.
- Heavy precipitation across portions of the Pacific Northwest,
the Northern Rockies, and the Northern Great Basin, Sun-Mon, Apr
14-Apr 15.
- Heavy precipitation across portions of the Northeast, the
Central Great Basin, the Northern Plains, the Northern Rockies,
the Central Rockies, and the Northern Great Basin, Mon-Tue, Apr
15-Apr 16.
- Heavy precipitation across portions of the Central Rockies and
the Central Plains, Wed-Thu, Apr 17-Apr 18.
- Heavy rain across portions of the Lower Mississippi Valley, the
Central Appalachians, the Tennessee Valley, the Great Lakes, the
Middle Mississippi Valley, the Mid-Atlantic, the Southern
Appalachians, the Southeast, the Southern Plains, and the Ohio
Valley, Tue-Thu, Apr 16-Apr 18.
- Heavy rain across portions of the Southeast, the Mid-Atlantic,
the Southern Appalachians, and the Tennessee Valley, Sun-Mon, Apr
14-Apr 15.
- Heavy rain across portions of the Great Lakes, the Mid-Atlantic,
the Northeast, the Central Appalachians, and the Ohio Valley,
Mon-Tue, Apr 15-Apr 16.
- Severe weather across portions of the Southeast, the
Mid-Atlantic, the Lower Mississippi Valley, the Southern
Appalachians, and the Tennessee Valley, Sun, Apr 14.
- Flooding possible across portions of the Middle Mississippi
Valley, the Great Lakes, the Upper Mississippi Valley, and the
Northern Plains.
- Flooding occurring or imminent across portions of the Lower
Mississippi Valley, the Northern Plains, the Tennessee Valley, the
Northern Great Basin, the Middle Mississippi Valley, the Upper
Mississippi Valley, the Pacific Northwest, and the Ohio Valley.
- Flooding likely across portions of the Upper Mississippi Valley
and the Northern Plains.
- Much below normal temperatures across portions of the Southern
Rockies, the Central Rockies, the Southern Plains, and the Central
Plains, Sun, Apr 14.
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