Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Sun Mar 13 2022
Valid 12Z Wed Mar 16 2022 - 12Z Sun Mar 20 2022
...Overview...
Several systems will quickly pass through the lower 48 during the
extended period within the relatively progressive and gradual
amplifying flow. The initial system over the Southeast will track
up the Carolina Coast before exiting into the Atlantic. Low
pressure organizing Thursday over the Southern Plains is expected
to lift northward through the Central U.S. Friday into Saturday
bringing active weather to central/eastern U.S. while the Pacific
Northwest remains unsettled with widespread precipitation likely
returning next weekend. No significant cold air outbreaks are
anticipated and temperatures will oscillate between normal and
much above normal ahead of the various waves of low pressure.
...Guidance Evaluation/Predictability Assessment...
The latest guidance is fairly clustered with the gradually
amplification of the flow over the lower 48 through the first half
of the period. Spread does begin to increase with the timing and
amplification by the end of the weekend and into next week. A
general blend of the ECWMF/GFS/CMC/UKMET was applied initially and
continued to provide predictability with the main synoptic
features over the CONUS.
As previously note, the GFS is persistent on remaining the
faster/progressive solution within the cluster and this is causing
the QPF placement to be further north/east especially across the
Plains and Southeast U.S. with the first system that passes
through and with the one over the Plains. For day 6 and 7, the
overall flow pattern will amplify, favoring deep troughing over
the West and the East. Given the degree of spread, the ECWMF
ensemble mean and the GEFS mean were included beyond day 5
increasing in its weighting to 40 percent by the end of the
period.
...Weather Highlights/Threats...
Widespread showers and thunderstorm are expected across the Gulf
Coast states and Southeast as a slow-moving system tracks through
Wednesday and Thursday. There may be elevated risk for excessive
rainfall along the coastline where there will be better alignment
of large scale lift and moisture advection. The next wave of low
pressure lifting through the central U.S. into the Great Lakes
late Thursday into Saturday will work with increasing Gulf
moisture and large scale lift. This should result in an expanding
area of showers and thunderstorms with some potential of winter
weather on the cold/northwest side of the system. The exact
details on any significant accumulations are too uncertain at this
time.
Another large scale and potentially strong system is expected to
pass through the West bringing beneficial rainfall to the Pacific
Northwest and perhaps as far south as central California. No major
Arctic air intrusions are expected through the period and
temperatures will generally trend normal to above normal with the
greatest departures from normal expected along/ahead of the
various waves of low pressure moving through the flow.
Campbell
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
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