Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
105 AM EDT Wed Jul 24 2019
Valid 12Z Sat Jul 27 2019 - 12Z Wed Jul 31 2019
...Weather Highlights/Threats and Guidance/Predictability
Assessment...
Latest models still indicate that eastern US upper troughing will
gradually deamplify this weekend into early next week as a mid
level ridge builds across Florida. A weakening front in Florida
and into the Gulf of Mexico will remain a main focus for heavier
convection and rainfall, with return warm/moist advection early
next week allowing activity to move north across the lower to mid
MS Valley and TN Valley and then into the Appalachians Wed 31 July.
A persistent feature in the upcoming pattern will be a closed high
over the Southwest. Expect daily scattered monsoonal convection
will work around the ridge over the southern Great
Basin/Rockies/High Plains in upper diffluent flow, and pockets of
above normal temperatures in the interior CA/OR and across
NV/ID/AZ.
Mid-level impulses and wavy surface fronts will traverse the
northern tier states from the Pacific Northwest eastward to the
Great Lakes and eventually the northeast. These will enhance
moisture, instability and showers/storms from the n-central U.S.
into the Midwest/Great Lakes.
Teleconnections from the Southwest ridge corresponds to a trough
from the Great Lakes to the lower OH Valley, where rainfall
probabilities increase from early to middle portions of next week.
The 12-18Z GFS forecast this trough further east than the GEFS
Mean/ECMWF Mean/operational ECMWF. Given the non-GFS solution
correspond better with teleconnections next week, the preferred
blend did not include the 12-18z GFS.
The WPC medium range product suite was mainly derived from a blend
of the 12-00 UTC ECMWF/18 UTC GEFS/12 UTC ECMWF ensemble mean.
This maintains good WPC continuity. The inclusion of the older
00z ECMWF helped mitigate the faster 12z ECMWF run in moving the
northeast Pacific trough onshore and inland faster than the
model/ensemble majority Wed 31 July.
Petersen
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