Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
153 PM EDT Tue Mar 24 2020
Valid 12Z Fri Mar 27 2020 - 12Z Tue Mar 31 2020
...Southwest U.S. to North-Central U.S. to Northeast Storm Threat
Friday-Monday...
...Guidance/Predictability Assessment...
A deepening area of low pressure from the central Plains toward
the Upper Midwest and Great Lakes later this week and into the
weekend highlights the medium range period. The product suite was
primarily derived from a blend of the 00Z ECMWF, 06Z GFS, and 00Z
UKMET initially. By day 6-7, the increasing model spread and
higher forecast uncertainty leads to overall lower confidence such
that more emphasis was placed on the 00Z ECENS ensemble mean,
though some inclusion of the 06Z GEFS mean was incorporated.
...Weather/Hazard Highlights...
Anomalous positively tilted trough axis ejects out into the
central Plains during the day 3-4 time frame resulting in a
deepening area of low pressure that is expected to track from the
Central Plains Friday to the Midwest/Great Lakes and Northeast
Saturday through early next week. In the warm sector, stronger
convection is possible while interactions along a stationary/wavy
frontal boundary will focus heavier rainfall from the Ohio Valley
through portions of the central Appalachians and Mid-Atlantic. The
signal remains for a northern tier banded precipitation which
could bring a threat for heavier snow/wind from portions of the
north-central Plains to the Upper Midwest and Great Lakes regions.
Out West, the Northwest will see periods of rain and mountain snow
of varying intensity as progressive flow from the northeast
Pacific carries along multiple features. Especially by the latter
half of the period there is rapidly decreasing confidence in the
southern extent of precipitation. Highest totals for the five-day
period should be along favored Olympics/Washington Cascades
terrain.
The West will experience below normal temperatures late this week
with moderation over the weekend. Expect decent coverage of minus
10-20F anomalies for highs over central/southern parts of the West
into Fri. On the other hand a broad area of above to much above
normal temperatures will spread from the Southern Plains and
vicinity across much of the East late this week into the weekend.
Highest anomalies will likely be for morning lows, up to 15-25F
above normal versus 10-20F anomalies being more common for daytime
highs. Multiple locations may see daily records for highs and/or
warm lows from the Southern Plains eastward. Frontal passage will
bring temperatures down to near normal over the eastern half of
the country by Sun-Mon.
Schichtel/Taylor
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