Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1158 AM 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

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