Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1104 AM EST Thu Jan 31 2019

Valid 12Z Sun Feb 03 2019 - 12Z Thu Feb 07 2019

...Warmed Central-Eastern U.S. Flips Back to Cold and Offers
Several Winter Storm Threats...
...Cold and Stormy Pattern for the West...


...Guidance/Predictability Assessment...

The WPC medium range product suite has accordingly been derived
from a composite of the 06 UTC GEFS mean and 00 UTC ECMWF/ECMWF
ensemble mean. These forecasts in particular now seem quite well
clustered through medium range time scales, bolstering forecast
confidence despite the transitional nature of the flow. This
solution is on the more amplified edge of the overall solution
envelope for next week, reflecting a pronounced recent model and
ensemble trend. This trend to a lesser extent is also evident in
the GFS, FV3, Canadian and UKMET. WPC continuity has been adjusted
to reflect this significant guidance trend.

...Weather Highlights/Hazards...

A much milder weather pattern will be prevalent across a majority
of the central and eastern U.S. by this weekend as flow from the
Gulf of Mexico advects higher humidity over the region. A couple
of well defined low pressure systems are expected to track across
the Plains and Midwest/Great Lakes before lifting into eastern
Canada over the medium range period, with the potential for
significant snow and winds to the north of the main surface lows
across the northern Rockies/Plains and Upper Midwest/Great Lakes
as arctic airmasses settle southward with and in the wake of these
deepened low down through the central then east-central U.S. with
later period frontal progression into the East slowed by a
building mean ridge aloft. Showers and storms are also likely to
develop from the Gulf Coast to the Midwest and eastern state in
the warm sectors of the main surface lows.  Some of this rainfall
have a risk to become locally heavy.

Meanwhile out West...the guidance trend toward development of a
much more amplified mean mid-upper level trough next week is
complicated by changing shortwave trough systems to dig/reinforce
the main longer wave feature. That said, forecast confidence is
above average in the overall idea that much of the West will
become increasingly cold and stormy next week with passage of
multiple systems/height falls. The wintery threat will include
heavy rain and mountain snow for much of California and for
terrain of the Intermountain West and Rcokies as a strong Pacific
disturbances moves inland.

Schichtel


WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation and winter weather outlook
probabilities are found 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