Skip Navigation Links 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center



Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/

Satellite and Radar Imagery
  GOES-East Satellite
  GOES-West Satellite
  National Radar
Product Archive
WPC Verification
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
WPC Overview
   About the WPC
   WPC History
   Other Sites
Meteorological Calculators
Contact Us
   About Our Site is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
Extended Forecast Discussion
(Latest Discussion - Issued 0648Z Aug 14, 2020)
Version Selection
Versions back from latest:  0   1   2   3   4   5   6   7   8   9   10   
Abbreviations and acronyms used in this product
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
247 AM EDT Fri Aug 14 2020

Valid 12Z Mon Aug 17 2020 - 12Z Fri Aug 21 2020

...Dangerous heat for much of the West early next week...


A strong upper high will meander near the Desert Southwest next
week while troughing will retrograde slightly in the East. Well
above normal temperatures will approach and exceed records for
many locations from Idaho southward through the Colorado River
Valley. Rainfall will be focused over the Southeast around a
stalled front with lighter amounts over parts of the Rockies and
Upper Midwest.

...Guidance/Predictability Assessment...

With good ensemble agreement overall, the deterministic models
showed acceptable clustering so that a blended approach was used
as a starting point to the forecast. Uncertainty increased atop
the upper high with incoming Pacific shortwaves and how they
flatten the top side of the ridge over the Northwest and southern
Canada. In the East, lead troughing will exit northeastward but be
reinforced by the end of the week, tugging the axis westward.  GFS
runs may have been on the more aggressive side overall so the
ECMWF was weighted a bit more than the GFS. The UKMET/Canadian
offered some detail to the forecast though each was less
consistently clustered near the ensembles means.

...Weather/Hazard Highlights...

Upper high will promote record heat for many areas west of the
Rockies while some showers/storms may fire on the east side of the
Rockies over Colorado and New Mexico with limited moisture. Record
high max and min temperatures will persist over the Desert
Southwest and surrounding areas through the Great Basin and inland
areas of California through at least the first half of the week,
perhaps cooling a bit by next Thu/Fri. Temperatures in the 100s
will be common with highest readings over 120F in Death Valley.
Little to no rainfall is expected under the upper high.

With troughing over the East, showers/storms will be favored over
the Southeast westward to Texas especially in the afternoon. This
may drift northward into the Mid-Atlantic midweek as the front
wanders along the coast. Northern stream troughing will bring in
cooler than normal temperatures to portions of the Plains and
mid-Mississippi Valley through the week with the best rainfall
chances over the Upper Midwest.


Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at: