Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EDT Wed Jun 05 2019
Valid 12Z Sat Jun 08 2019 - 12Z Wed Jun 12 2019
...Excessive Rain and Flash Flood/Flooding Threat to slowly spread
across the Mid-South and Southeast into the
Appalachians/Mid-Atlantic this weekend into early next week...
...Guidance...
The WPC medium range product suite was primarily derived from a
composite blend of the compatable GFS/ECMWF and Canadian models
this weekend, transitioning to GEFS/NAEFS and ECMWF ensemble means
next week amid growing forecast spread. This solution maintains
good WPC continuity.
...Mid-South/Southeast/Appalachains Impacts...
A slow moving/amplified southern stream upper trough and surface
system will lure deep moisture return from the Gulf of
Mexico/Atlantic, fueling a prolonged threat of heavy rain and
flash flooding/flooding. There is a strong signal for a slow
spread of activity Saturday-Tuesday from the Mid-South and
Southeast to the Appalachians/Mid-Atlantic. WPC medium range QPF
advertises 3-6" areal average amounts, with locally higher amounts
possible in areas of cell training/back building/cell mergers and
favored southern Appalachians terrain. Deepest tropical moisture
is linked to a Gulf of Mexico disturbance now off southern Texas
that remains monitored by NHC.
...U.S. Northern Tier Impacts...
A significant/anomalous cooling and unsettling upper troughing in
northern stream flow evolves from the Northwest/West,
north-central U.S. and eastward this weekend into early next week.
Guidance has overall recently converged on a more clustered
forecast, bolstering confidence in widespread moderate to terrain
enhanced precipitation. This includes weekend snows for northern
Rockies higher elevations of per WPC medium range winter weather
outlook probabilities. Rain potential will spread eastward
along/ahead of the main upper trough/surface frontal system and
eventually entrains deeper moisture from lower latitudes/Atlantic
for the East early next week.
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