Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Thu May 31 2018
Valid 12Z Sun Jun 03 2018 - 12Z Thu Jun 07 2018
...Guidance/Uncertainty Assessment...
Model and ensemble guidance offer a reasonably similar larger
scale pattern over the nation as highlighted aloft by significant
troughs into the Northwest and downstream over the East
sandwiching an amplified/hot s-central us ridge. Recent guidance
has trended a bit toward a bit more amplitude and pattern
longevity. This trend seems reasonable. The depiction and
interactions of a multitude of mid-smaller scale systems embedded
with the flow however is proving to be quite problematic days 3-7
and forecast uncertainty with these is producing significant run
to run model issues. Accordingly, the WPC medium range product
suite was primarily derived from a composite blend of the 00 UTC
GEFS/NAEFS/ECMWF ensemble means.
...Weather Highlights and Threats...
Shortwaves reinforcing an upper trough in the East should support
a lingering surface front from the western Atlantic and Southeast
to the southern plains that should maintain some 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.
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
Schichtel