Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1100 AM EST Fri Mar 08 2019
Valid 12Z Mon Mar 11 2019 - 12Z Fri Mar 15 2019
...North-Central U.S. Heavy Snow Threat...
...South-Central U.S. to Mid-South/Southeast Heavy Rain/Convection
Threat...
...Overview...
Deep mid-upper level troughing near California Monday will head
eastward through the Southeast/Mexico Tuesday then northeastward
over the central to east-central U.S. midweek through next Friday
atop building ridging into the Southeast U.S./Cuba. In this
pattern, yet another robust late winter storm will lift out of the
Southwest Tuesday toward the Upper Midwest by Thursday. This will
likely lead to another round of heavy snow and high winds across
the north-central U.S. with heavy rain and strong convection
focused from the South-Central U.S. to the Mid-South/Southeast.
Slow movement of the cold front along the Gulf Coast may increase
the threat of locally heavy rain with the potential for multiple
inches of rain and flooding concerns given rather wet antecedent
conditions.
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 unsettled/wintry Great Basin and Rockies through
mid-late week will also act to slow the trough progression
eastward along the Gulf Coast.
...Guidance and Uncertainty Assessment...
The 00 UTC GFS/ECMWF and GEFS/ECMWF ensemble mean have converged
on a more well clustered solution days 3-7 and a composite was
used as a starting template for the WPC medium range product suite
today.
...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. 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).
Schichtel
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