Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Tue Mar 26 2019
Valid 12Z Fri Mar 29 2019 - 12Z Tue Apr 02 2019
...Overview and Weather Highlights and Hazards...
Strong upper ridging initially over British Columbia will drift
northwestward into Alaska which favors broad troughing through
central/eastern Canada and through the Upper Midwest/Great
Lakes/Northeast. Underneath the western Canadian high, weaker
shortwaves will drop through the Four Corners region and
eventually turn the corner across Texas early next week and head
eastward, possibly invigorating a surface boundary in the Gulf. In
the northern stream, low pressure will exit through the eastern
Great Lakes/St. Lawrence valley this weekend as the tail-end of
its cold front lingers across Florida. This system will bring a
variety of weather to the central/eastern states Fri-Sun: severe
weather for portions of Oklahoma on Friday (see SPC for more
info), well above average temperatures to the
Northeast/Mid-Atlantic Saturday, well below average temperatures
behind the front (especially over the Southern Plains into the
Midwest on Sunday), snow across the central Plains Fri/Sat, and
locally heavy rainfall ahead of and along the front initially in
the Midwest to Northeast but then perhaps over Florida next week.
The west will see another system push into WA/OR early next week
with only light to modest amounts of rain/snow.
...Guidance Assessment/Preferences...
Latest deterministic models were reasonably well-clustered for the
Fri-Sun period as the eastern system lifts into southeastern
Canada and the western shortwaves dip into the southern Rockies.
The 06Z GFS and 00Z UKMET became quicker/flatter than the 00Z
GFS/ECMWF/Canadian late Sat into Sun over the Four Corners but
weighted the slower solutions more than the quicker ones by about
a 3:1 ratio given the good ensemble clustering but still uncertain
evolution prior. Exodus of the eastern system was uncertain over
New England late Sun/early Mon as the GFS/Canadian runs were
quicker than the ECMWF/UKMET with a possible wave along the front.
For now, opted to keep the front more progressive given the
propensity of the ECMWF to be too slow, but many ensemble members
showed such development. Trended toward more ensemble weighting by
next Mon/Tue with details added per the ECMWF/Canadian off the
West Coast with an incoming system that the GFS runs have lost in
recent runs. Ensemble members strongly show a coherent low
pressure (albeit only of modest depth) moving toward the
Washington coast around next Tuesday with the front inland into
the Great Basin and central California.
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