Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
208 AM EDT Wed Jun 09 2021
Valid 12Z Sat Jun 12 2021 - 12Z Wed Jun 16 2021
...Much above normal temperatures and record heat this weekend
into early next week across much of the interior West/Northern
Plains....
...Overview...
Upper pattern is forecast to amplify along 105W this weekend into
early next week, promoting warm/hot temperatures over much of the
West and northern High Plains that may near or break daily
records. Troughing will exit but then build back into the East
where rainfall will focus over the Mid-Atlantic into the
Southeast. A Pacific front will push into the Pacific Northwest
early next week.
...Guidance/Predictability Evaluation...
The latest model guidance for the medium range period
(Saturday-Wednesday) is in reasonable agreement and offers average
to above average predictability and consistency. The upper flow
amplification driven by near +3 sigma height anomalies is well
agreed by the most recent deterministic and ensemble guidance. The
largest model spread exists with downstream troughing potential
for the Great Lakes to Northeast. With such strong ridging, the
deeper troughing has become a clearer signal and preferred pattern
but the depth and progressiveness remains uncertain. Upstream
energy and interactions with shortwave energy coming out of Hudson
Bay lower confidence by the middle of next week. With this in
mind, the WPC blend utilized the ECMWF/CMC/GFS followed by a ECENS
led blend by days 6-7.
...Weather Highlights/Hazards...
The amplification of the upper ridge over the central U.S. is
expected to bring another round of much above normal to possibly
record warm/hot temperatures to the northern Rockies and northern
Plains late this weekend and early next week. Temperatures may be
10-25F above normal with some triple-digit readings possible
across central/eastern Montana Monday and Tuesday. Nighttime lows
will also remain warm for the region and likely stay 10F to 15F
above normal for middle of June. Elsewhere across the CONUS,
temperatures are expected to be near to slightly above normal. The
strong/dominant upper ridge over the central CONUS will keep much
of the area void of significant or heavy rainfall, the exception
being possibly along the Gulf Coast to Southeast U.S. late this
weekend into early next week where a frontal boundary stalls and
lingers.
Taylor
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
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