Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
339 PM EDT Tue Jun 18 2019
Valid 12Z Fri Jun 21 2019 - 12Z Tue Jun 25 2019
...Weather Highlights/Threats...
An unsettling southeast Canada/Northeast U.S. upper trough and
coastal low will support lingering wrapping moisture/rainfall into
northern New England Friday into Saturday. The closed trough is
expected to slowly give way to a warming upper ridge building from
the east-central U.S./Southeast up into the Great Lakes into early
next week. Expect hot warm sector temperatures under this ridge
including a risk of record warm minimum values mainly for the
eastern southern Plains and lower MS Valley. This ridge builds
ahead of a series of upstream troughs that drift/reform from the
Northwest/West to the Rockies and Plains/south-central Canada. The
systems present an emerging threat of strong to severe/MCS
convection and locally heavy rains with
frontogenesis/cyclogenesis, pooling moisture/instability and
repeat cells. There is also a risk of some northern Rockies June
snows.
...Guidance/Predictability Assessment...
The WPC medium range product suite was derived from a composite
blend of compatable guidance from the 06 UTC GFS and 00 UTC
ECMWF/Canadian/UKMET days 3-5 then GFS/ECMWF and GEFS/ECMWF
ensemble guidance days 6/7 in a timeframe with increased but
manageable forecast spread. This maintains good WPC continuity,
albeit with most uncertainty still associated with the focus for
localized summertime convective weather and hazards.
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
Hazards:
- Heavy rain across portions of the Central Plains, the Lower and
Mid Mississippi Valley, into the
the Tennessee Valley, parts of the Ohio Valley, Central
Appalachians and the Great Lakes, Sun-Mon,
Jun 23-Jun 24.
- Heavy rain across portions of the Central Plains, the Middle
Mississippi Valley into the Upper
Midwest and parts of the Great Lakes as well as the Ohio Valley,
Fri-Sat, Jun 21-Jun 22.
- Severe weather across portions of the Central Plains, the Middle
Mississippi Valley, the Upper
Midwest, and the Northern Plains, Fri, Jun 21.
- Flooding possible across portions of the Central Plains, the
Middle Mississippi Valley, the Great
Lakes, and the Ohio Valley.
- Flooding occurring or imminent across portions of the Central
Plains, the Lower and Middle
Mississippi Valley, and the Ohio Valley.
- Flooding likely across portions of the Southern Plains, the
Central Great Basin, and the Northern
Great Basin.
- Excessive heat across portions of southern Texas, Fri-Tue, Jun
21-Jun 25.
- Excessive heat across portions of the Mid-Atlantic, Mon-Tue, Jun
24-Jun 25.
- Much below normal temperatures across portions of the northern
and central Rockies, the northern
High Plains, and into parts of the Great Basin, Fri-Sat, Jun
21-Jun 22.
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