Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Thu Jun 21 2018
Valid 12Z Sun Jun 24 2018 - 12Z Thu Jun 28 2018
...North-Central U.S. Heavy Convective Rainfall Pattern...
...Guidance/predictability Assessments with weather highlights...
Models and ensembles continue to show excellent agreement that a
split flow upper-level pattern across North America will gradually
become more consolidated by the middle of next week as heights are
forecast to increase over the central and eastern U.S. Until
then, a couple of upper-level shortwaves are expected to track
generally from the northern Rockies across the central Plains and
then lifts out into the Great Lakes. This modestly progressive
pattern appears to support the amplification of mesoscale
convective systems over the central Plains early next week where
locally excessive rainfall is possible. By the middle of next
week, models agree that the main energy associated with the
shortwaves will weaken and lifts toward the Great Lakes as a
Pacific front dips into the northern Plains. Some remnant
thunderstorms should push into the Ohio Valley into the
Appalachians by the middle of next week. Over the southeastern
U.S., a weakening front should promote showers and thunderstorms
from Florida westward into the central Gulf coast. Meanwhile, the
GFS has begun to indicate the possibility of a surface low
lingering just off the Carolina coast along the dying front toward
the middle of next week.
Accordingly, the WPC medium range morning product suite was
derived from a composite blend of the 00Z ECMWF and 06Z GFS
trending toward their ensemble means through Day 7. This
maintains excellent WPC continuity.
Kong
WPC medium range forecasts of 500 mb heights, surface systems,
weather grids, quantitative precipitation, and winter weather
outlook probabilities are found at:
http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4