Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1117 AM EST Sat Feb 02 2019

Valid 12Z Tue Feb 05 2019 - 12Z Sat Feb 09 2019

...Guidance/Predictability Assessment and Weather
Highlights/Hazards...

Models and ensembles agree in showing another stormy pattern
across the lower 48 states next week. This will be highlighted
Tuesday by a deepened low pressure center exiting the Northeast
and another potent/wet storm working into California and an
unsettled/wintery West. Arctic air will spill down over the
north-central through northeastern U.S. in the wake of the
Northeast storm. An uncertain series of smaller scale impulses
will act to induce local precipitation focusing frontal waves on
the leading edge of the arctic chill.

Guidance continues to be quite data sensitive and varied with
respect to subsequent progression and phasing potential of the
main California system Wed-Fri on a general track northeastward
across the central and northeastern U.S. Despite timing issues,
this storm offers a considerable threat of heavy snow/ice in the
arctic air in place to the north of e main low track over the
n-central through northeastern states along with some threat of
heavy warm sector rains/convection. The deepened arctic airmass is
slated to spread arcoss much of the nation in the wake of this
system. Given uncertainty, the WPC medium range product suite was
primarily derived from a composite guidance solution that includes
the latest GFS/ECMWF/Canadian and GEFS/ECMWF ensembles. Ensemble
membership is so varied in timings that inclusion of also varied
deterministic model guidance was needed to show ample system
developments consistent with dynamic support aloft. This type of
blended solution is not ideal, but the resultant system depictions
produced in this manner seems to offer a fair flow representation.

In this pattern, temperatures will be much below average (20-40
degrees negative anomalies) over the northern Plains/vicinity next
week behind the arctic front. The east/Southeast will see much
milder temperatures ahead of a lead cold front Tue/Wed that again
rise Thu/Fri ahead of the next arctic surge before that front
pushes offshore. Some record highs are possible.

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