Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1122 AM EDT Wed May 30 2018
Valid 12Z Sat Jun 02 2018 - 12Z Wed Jun 06 2018
...Record heat expected across the southern Plains...
Guidance and uncertainty assessment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Latest model and ensemble guidance offer a reasonably well
clustered range of solutions this weekend into day5/Monday in a
pattern with average predictability. Guidance spread increases
thereafter, with 06/18 UTC GFS runs notable outliers. Recent ECMWF
trends have been toward stronger systems moving through Canada and
WPC progs have been shaded in that direction. Overall though, WPC
continuity was well maintained with a composite blend of the 00
UTC GFS/ECMWF/ECMWF ensemble mean and the favorably trending 06
UTC GEFS, but opted to drop the GFS days 6/7 amid growing forecast
spread/uncertainty. Canadian ensembles offer this general
scenario, but recent UKMET/Canadian determinitsic runs have been
less consistent.
Weather Highlights and Threats
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Shortwaves reinforcing an upper trough in the East should support
lingering wet weather for the Mid-Atlantic and the Southeast into
the weekend. A lingering surface front from the western Atlantic
and Southeast to the southern plains remains a focus for deeper
moisture pooling and some heavier local convective downpours next
week, albeit with main low genesis offshore. Upstream, an
amplifying trough position over the Northwest should generate some
late season rainfall and some cooling. A less certain stream of
ejecting energy/height falls will also support an extended pattern
favorable for locally heavy convection/rainfall over the
Plains/Midwest with low/front genesis to include some risk of
severe weather as per SPC.
The dominant focus of the temperature forecast will be on a
multi-day Texas heat wave expected to persist into Sunday whose
influence may extend at times northward into the central Plains
and eastward into the western Gulf coast. Hot afternoon readings
in the 100-110F range should be most common in the lower Rio
Grande, with Saturday setting up to be the hottest day. Record
warm values for high and low temperatures will be reached/exceeded
during this time frame. The southward suppression of the heat in
Texas with time from Sunday onward occurs as a front settles
southward and ridging aloft over the area slowly weakens.
Schichtel
WPC medium range forecasts of 500 mb heights, surface systems,
weather grids, quantitative precipitation, and winter weather
outlook probabilities can be 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