Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 AM EDT Wed Mar 13 2019
Valid 12Z Sat Mar 16 2019 - 12Z Wed Mar 20 2019
...Overview...
Upper ridging over western Canada will slowly nudge eastward next
week with its axis down the spine of the Rockies. This favors
broad troughing downstream over the central/eastern states and a
slowly approaching trough off the West coast as well as a southern
stream trough moving across Mexico Monday and through the Gulf
next Tue/Wed.
...Guidance Assessment/Preferences...
The 18Z GFS/FV3-GFS and 12Z ECMWF offered reasonable clustering
near their ensemble means such that a blended solution was
utilized for the first few days of the period (Sat-Mon). By next
Tue/Wed, differences in the upstream shortwave speed/track expand
as they move across the northern tier and/or get left behind under
the expanding ridge (or upper high) over Alberta/Saskatchewan. In
the Pacific, trend has been toward a deeper/slower trough or upper
low that may aim toward southern California (or even Baja
California Norte) and opted to weight the ECMWF ensemble mean more
than the GEFS mean as it was deeper, but not as deep as the
deterministic run.
...Weather Highlights and Hazards...
A cold front will settle near the Florida Keys as a wavy
stationary front late this weekend, providing a focus for rainfall
through the period. The combination of this front and one or more
southern stream shortwaves aloft may produce periods of locally
moderate or heavy rainfall over the Florida Peninsula. Extreme
southern Texas may see some enhanced rainfall with the energetic
flow aloft as well. The rest of the East will see a drier period
except for some areas of lake enhanced snow as weak fronts rotate
through the Lakes. The West should be mostly dry until moisture
reaches the West Coast around next Tue and especially Wed, focused
from NorCal northward west of I-5.
The north-central and southern Plains may see the most persistent
cold anomalies with some locations at least 15-20F below normal
for highs through the weekend. The warming trend over/near the
West Coast states should bring readings 5-10F above normal by
Sun-Tue that will shift into Idaho next Wed. The East will
generally see cooler than normal temperatures through the period
due to northwesterly flow.
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