Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 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
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