Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Fri Sep 13 2019
Valid 12Z Mon Sep 16 2019 - 12Z Fri Sep 20 2019
...Potential Tropical Cyclone NINE Threatens the Southeast U.S.
Coast...
...Overview and Guidance Evaluation/Preferences...
The latest deterministic models and ensembles offer a reasonably
similar larger scale pattern evolution into much of next week, but
really show a wide range of solutions with embedded systems over
time. This is especially evident with Potential Tropical Cyclone
NINE. In order to produce a medium range product suite consistent
with the latest NHC track and intensity forecast, blended the more
run to run consistent GEFS/ECMWF ensemble means for larger scale
flow and then applied significant "NINE" manual adjustments.
...Weather Highlights/Threats...
"NINE" is forecast to bring numerous showers and thunderstorms
along its uncertain track. The current track offers a heavy
rain/weather threat for coastal FL/GA/SC/NC.
Amplified upper low/trough passage and surface system genesis will
support widespread rains (and some mountain snows) across the
Pacific Northwest before spreading south into CA and inland across
the Great Basin and northern Rockies next week. Southerly flow
east of the upper trough looks to revive monsoonal showers/storms
into the Four Corners region. Ample convective potential should
also reach the n-central U.S. with system/height fall progression
into mid-later next week.
While western to n-central U.S. system development and progression
provides widespread cooling and unsettled weather, lead amplified
upper ridging will result in above average temperatures from the
Plains to the east-central states next week. Warm overnight
temperatures will offer max chance of approaching record values
over the n-central U.S. and in humid air from the central Gulf
Coast to the coastal Southeast closer to "NINE".
Schichtel
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