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Extended Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0503Z Jul 23, 2019)
 
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Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
103 AM EDT Tue Jul 23 2019

Valid 12Z Fri Jul 26 2019 - 12Z Tue Jul 30 2019

...Weather Highlights/Threats and Guidance/Predictability
Assessment...

The models indicate a deamplifying eastern US trough this weekend
as a mid level ridge builds across Florida. A weakening front in
Florida and into the Gulf of Mexico will remain a main focus for 
convection/rainfall, with return warm/moist advection early next
week allowing activity to move north across the lower MS Valley
and southeast.

The mode persistent feature is the closed anticyclone over the
southwest. Expect daily scattered monsoonal convection will work
around the ridge over the southern Great Basin/Rockies/High Plains
in upper diffluent flow, and pockets of above normal temperatures
in the interior CA/OR across NV/ID/AZ.

Mid-level impulses and wavy surface fronts will traverse the
northern tier states from the Pacific Northwest eastward to the
Great Lakes. These will enhance moisture, instability and periods
of convection/MCS activity, especially from the n-central U.S.
into the Midwest/Great Lakes.  Teleconnections from the southwest
ridge corresponds to a trough from the Great Lakes to the lower OH
Valley, so rainfall probabilities increase in these areas early
next week.  Downstream from the trough, above normal temperatures
redevelop over the northern mid Atlantic to the upper OH Valley
and New York/New England early next week.

Model forecasts cluster well with ensembles this weekend, with
forecast spread then increasing more early next week. WPC medium
range surface fronts/pressure/precipitation probability forecasts
were primarily derived from a blend of the 12 UTC
GFS/ECMWF/UKMET/Canadian models with the 18 UTC GEFS mean and 12
UTC ECMWF ensemble mean. This maintains good continuity.  The 18z
GFS had a closed low on the southern edge of the guidance
distribution near the British Columbia/Alberta border early next
week, so the forecast incorporated the 12z GFS run instead.

Petersen


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