Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1136 PM EDT Thu Sep 05 2019
Valid 12Z Mon Sep 09 2019 - 12Z Fri Sep 13 2019
...Record heat to continue for the Lower Mississippi Valley/Gulf
Coast next week...
...Overview...
Upper ridging will remain anchored over the Lower Mississippi
Valley and Southeast next week, with additional positive height
anomalies diving southeastward out of far NW Canada to Hudson Bay.
The West will see a series of upper troughs moving through the
region with the lead system weakening into the Great Lakes
Tuesday. Another system exiting the West late Wednesday into
Thursday may be more robust.
...Guidance Evaluation and Preferences...
A blend of the 18Z GFS and 12Z ECMWF/Canadian formed a good
consensus cluster near the ensemble means through the period. The
exception during the medium range may be over the Northeast around
Wed/Thu as the 18Z GFS (and 12Z run) was much quicker/deeper with
the surface low pressure as a result of phasing in a northern
stream shortwave. Ensemble consensus suggested this was not likely
as the members showed rather zonal flow with little amplitude. GFS
runs were in the deepest 10% of the ensemble members with this
feature and was not preferred. However, by next Friday, that
system will exit the CONUS and the 18Z GFS again fit the consensus
with deepening low pressure through the High Plains into the Upper
Midwest. This may be a precursor to a pattern change over the West
perhaps due to the upstream extratropical transition of Typhoon
Lingling and Tropical Storm Faxai which may lead to deep troughing
in the Bering Sea and ridging downstream into western North
America.
...Sensible Weather...
The Southern tier of the CONUS from east Texas eastward to the
Florida panhandle will generally see well above average
temperatures in the upper 90s to lower 100s F that are forecast to
tie or break record highs. Much of the West and Northern
Rockies/High Plains will see below average temperatures in a
generally stormy/wet pattern. Mild temperatures, about 5-10F above
average, are favored for the mid-Mississippi Valley eastward
through the Ohio/Tennessee Valleys to the south of a frontal
boundary.
Rainfall will be mostly confined to northern areas along the storm
track. Pockets of heavier rain may be possible across the High
Plains into the western Great Lakes region around the surface low
and in advance of the warm front Mon-Tue. Another chance of
widespread rain with embedded heavier elements will be possible
next Thu/Fri from eastern Montana into Minnesota as low pressure
deepens over the Plains. In the Southwest, moisture out of Mexico
will likely lead to a daily chance of mountain showers/storms that
could move into desert valley locations (southern Arizona and
portions of New Mexico) and perhaps into extreme western Texas.
Chances of rain should decrease though the week there.
Fracasso
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