Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Fri Jun 21 2019
Valid 12Z Mon Jun 24 2019 - 12Z Fri Jun 28 2019
Troughing returns to the Pacific Northwest next week as an upper
low slowly sinks southeastward from the Gulf of Alaska then
eastward into Washington/Oregon. To the east, a lead system will
lift northeastward through the Great Lakes with a ridge developing
over the northern Plains in its wake. Upper ridging is forecast to
slide westward across the Gulf of Mexico and into the Mexican
plateau and far western Texas/southern New Mexico with a weak
trough pushing west across Florida to the central Gulf Coast
starting in the middle of next week.
A blend of the deterministic 00Z ECMWF/UKMET/06Z GFS guidance
offered a good starting point for the Mon-Wed forecast.
Differences in timing with the eastern system continued to
diminish with these runs for Day 3. Excellent agreement with the
system approaching the Pacific Northwest coast ends with
divergence on Wed with the shape and depth of the mid-level low
center. Differences are also noted in the 00Z ECENS/GEFS with the
GEFS deeper. Uncertainty remains with the timing/influence of a
reinforcing shortwave from the northern BC coast Thursday. For now
went with the less intense solution with the 00Z ECENS which
replaced much of the deterministic input for Days 6/7. Farther
east, ensembles were in good agreement on moving the weak trough
eastward along with its surface cold front and for the ridge over
the southeastern 2/3 of the CONUS. It is worth noting that the 00Z
and 06Z GEFS both have a mid-level inverted trough shifting west
across the northern Gulf of Mexico on Day 7.
Much of the central and northern Rockies will see below normal
temperatures on the order of 5-10 deg F on Monday with cold
returning to the West Coast and pushing inland for the rest of
next week under the developing trough. Areas from the High Plains
to the Northeast will see near to above normal temperatures (up to
about +5 to +10 deg F anomalies) through the forecast period, but
generally not near record maxes. The cold front will not bring in
much colder air to the East but rather a bit drier (briefly).
Southern Plains to the Southeast will see 90s most days with a
sprinkling of showers/storms during the afternoons.
Precipitation forcing will be best Mon/Tue across the northeast
ahead of a warm front lifting north from the Great Lakes low. In
the Pacific Northwest, an upper low will bring in showers (and
some very high elevation snow) that will gradually expand over the
northern Plains to the Upper Midwest later in the week as the
trough and cold front move eastward. There is potential for
notable precipitation along the central Gulf Coast by Fri as a
weak upper level disturbance shifts west from Florida, possibly
providing forcing to an onshore flow.
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
- Heavy rain across portions of the Lower Mississippi Valley and
the Southern Plains, Mon, Jun 24.
- Flooding possible across portions of the Northeast, the Southern
Plains, the Middle Mississippi Valley, the Mid-Atlantic, the Great
Lakes, and the Ohio Valley.
- Flooding occurring or imminent across portions of the Central
Plains, the Lower Mississippi Valley, the Tennessee Valley, the
Middle Mississippi Valley, the Mid-Atlantic, and the Ohio Valley.
- Flooding likely across portions of the Central Great Basin.
- Excessive heat across portions of the Southeast and the Southern
Texas, Mon, Jun 24.
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at: