Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
217 AM EDT Thu Sep 05 2019
Valid 12Z Sun Sep 08 2019 - 12Z Thu Sep 12 2019
...Record heat to continue for the Lower Mississippi Valley/Gulf
Coast into next week...
...Overview...
Upper ridging will remain anchored over the Lower Mississippi
Valley and Southeast into next week. The West will see a series of
upper troughs moving through the region with southwest flow across
the Plains. Low pressure emerging from the West early in the week
should track eastward along the US/Canadian border to the east
coast around next Thursday.
...Guidance Evaluation and Preferences...
The 12Z/18Z GFS and 12Z ECMWF offered reasonable clustering near
their respective ensemble means and each other through the period.
The 12Z UKMET/Canadian differed mostly in the West and upstream
over the northeastern Pacific and were not preferred. Blended
approach remedied any timing/track/amplitude differences among the
GFS/ECMWF deterministic runs.
...Sensible Weather...
Fall-like temperatures (10-15F below average; highs in the 60s)
over the High Plains/Upper Midwest Sunday will moderate only
slightly through the week (5-10F below average). The Southern tier
of the CONUS from Texas eastward to Florida will generally see
well above average temperatures in the mid-90s to around 100F that
are forecast to tie or break record highs, especially on Sunday
but still continuing through at least Wednesday. Much of the West
will see below average temperatures under upper troughing, with
lowest anomalies tending to be over north-central areas and the
northern Rockies.
Rainfall will mostly favor the northern areas from the Pacific
Northwest eastward as the frontal system moves toward the Great
Lakes and then Northeast by later next week. 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. In the Mid-Atlantic region, stalling front late this
weekend into early Monday may help expand an area of generally
light rain before high pressure to the north moves in by Tuesday.
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.
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