Quantitative Precipitation Forecast Discussion
NWS Weather Prediction Center College Park MD
1200 AM EST Sun Mar 04 2018


Prelim Day 1 QPF Discussion
Valid Mar 04/1200 UTC through Mar 05/1200 UTC
Reference AWIPS Graphics under...Precip Accum - 24hr


Day 1

...Northern Rockies/Northern Plains...
A mid- to upper-level low moves from Oregon into the northern
Plains, aiding the spin-up of a Colorado low which then progresses
northeast into South Dakota.  There has been a trend towards
increasing surface troughing/850 hPa frontogenesis across Montana
which had led to some increase and westward expansion of QPF
within the model guidance.  After coordination with the Great
Falls, MT forecast office, trended westward in suit.  Across the
northern Plains, the pattern is messy with a pair of areas with
good low- to mid-level frontogenesis which shift east with time. 
Overall, resemble a compromise of the 00z GFS, 12z ECMWF, and the
00z mesoscale guidance which kept reasonable continuity.  Much of
this precipitation is expected to be in the form of snow -- see
our Winter Weather suite of products for more information on
winter weather impacts.


...Lower to Mid-Mississippi Valley...
A return flow of moisture near the surface from the Gulf of
Mexico, with a continued connection aloft from offshore Baja
California, is expected to interact with a warm front to generate
showers and thunderstorms from the ArkLaTex into Missouri and
southeast Iowa.  The southern limit of any hydrologically
significant precipitation is expected to be marked by the 6C
isotherm at 700 hPa across Texas and Louisiana.  Precipitation is
expected to be progressive this period before a new batch reloads
near the ArkLaTex on day 2/Monday.  After looking at GFS mass
fields, went with a precipitation pattern slightly wetter than the
00z ECMWF which was an increase from the previous WPC QPF.   

Roth