Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
111 AM EST Fri Mar 08 2019
Valid 12Z Mon Mar 11 2019 - 12Z Fri Mar 15 2019
...Active weather pattern for the central states through next week
with additional snow possible for the High Plains/Upper Midwest...
...Heavy rain quite possible over the Southeast/TN Valley late
next week...
...Overview...
The work week next week will feature yet another robust late
winter storm lifting out of the Southwest Tuesday toward the Upper
Midwest by Thursday. This will likely lead to another round of
snow across the High Plains with rain/convection focused across
the Southeast and Tennessee Valley. Slow movement of the cold
front along the Gulf Coast may increase the threat of locally
heavy rain with the potential for several inches of rain and
flooding concerns given rather wet antecedent conditions.
...Guidance and Uncertainty Assessment...
Deep troughing near California at the start of the period Monday
will head eastward then northeastward atop building ridging into
Cuba. Ensembles have been split on the timing of this evolution
with the GEFS members quicker than the ECMWF and Canadian
ensembles. Most recent 12Z and 18Z GEFS have trended slower with
the progression while the ECMWF/Canadian ensembles remained
steady. With the 18Z FV3-GFS nearer to the 12Z ECMWF than the
operational 18Z GFS, placed much more emphasis on the 12Z
ECMWF-led cluster that included the UKMET and Canadian with the
12Z ECMWF ensemble mean and 12Z NAEFS mean. By next Thu/Fri, the
surface low will exit through the Great Lakes and southern Ontario
into Quebec but its attendant cold front will slow as it runs into
the ridging to the east and becomes oriented near-parallel to the
upper flow. Additional height falls upstream through the Great
Basin on Wednesday will also act to slow the trough progression
eastward along the Gulf Coast. Ensembles were in good agreement in
the east overall but differed on the details including possible
surface wave development along the cold front.
...Weather Highlights and Hazards...
Snow will exit New England Monday though lake-enhanced snow will
persist on the windy backside flow around the exiting deep low
until a surface high builds in by Tuesday. Areas of rain and
thunderstorm activity will persist across the Gulf Coast region
along/ahead of a frontal boundary. Colder than average
temperatures will persist over much of the western states on the
order of 5-15F below climo. Temperatures in the east will be a bit
more variable--near average early in the week but trending milder
later in the week ahead of the central Plains system.
Main system of interest in the medium range will start in the
West/Southwest with precipitation moving through Southern
California and the Southwest Deserts. Precipitation will expand in
coverage from New Mexico eastward, focused on the central/southern
Plains from KS southward to northern Texas Tue/Wed as the surface
low deepens from New Mexico into southwestern Kansas. Front across
the Gulf will lift northward as the low heads toward Minnesota by
Thursday morning which will bring widespread rainfall and embedded
convection into the Mississippi/Tennessee Valley. The potential
for several inches of rain exists over a large area that will be
further refined over the next several days. Atmospheric and
ensemble signals were notable even at this lead time but QPF was
kept lower than any given model given timing/detail uncertainty.
To the north, cold enough air will support snow on the
northwest/north side of the surface low that will occur with
strong winds (i.e., possible blizzard conditions).
Fracasso
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are 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
https://www.wpc.ncep.noaa.gov/heat_index.shtml