Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
255 AM EDT Thu Jun 06 2019
Valid 12Z Sun Jun 09 2019 - 12Z Thu Jun 13 2019
...Excessive Rainfall and Flash Flood/Flooding Threat to slowly
spread northeastward from the Southeast through the Appalachians
and Eastern Seaboard into early next week...
...Guidance and Predictability Assessment...
The WPC medium range product suite was primarily derived from a
composite blend of reasonably compatable GFS/ECMWF/UKMET/Canadian
model guidance Sunday into Tuesday, transitioning more to
GEFS/ECMWF ensemble means amid growing forecast spread. This
maintains good WPC continuity.
...Southeast/Appalachians/Eastern Seaboard...
An amplified southern stream upper low/trough and wavy surface
system settles over the Southeast into early-mid next week and
will continue to tap deep moisture from the Gulf of
Mexico/Atlantic to fuel a lingering threat of heavy rain and flash
flooding/flooding across the region. There is also a strong signal
to lift moisture and energy northeastward across the
Appalachians/Eastern Seaboard with interaction with northern
stream flow and with surface frontal approach. WPC medium range
QPF early next week offers widespread 1-4" areal average amounts,
with heaviest totals focusing over the Southeast. Locally higher
amounts remain possible in areas of cell training/back
building/cell mergers and especially into favored Appalachians
terrain. These values are in addition to totals expected over the
next 3 days.
...U.S. Northern Tier...
A amplified/cooling lead upper trough in northern stream flow will
progress from the north-central U.S. to the Northeast
Sunday-Tuesday. Rain/Showers will spread eastward along/ahead of
the upper trough/surface frontal system and eventually entrain
deeper moisture from lower latitudes and Atlantic that offers a
risk of much heavier rainfall potential early next week. There is
an increasing guidance signal for upstream trough
amplification/surface system genesis back over the east-central
U.S. through next midweek to renew lead precipitation potential.
...Southern Rockies.High Plains...
A series of upper impulses riding into the southern Rockies/High
Plains, favorable upper diffluence and upslope fetch/trailing
surface front convergence may lead to some daily risk of moderate
convection/rainfall, especially in the Sunday-Tuesday 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