Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1212 PM EDT Fri Jul 06 2018
Valid 12Z Mon Jul 09 2018 - 12Z Fri Jul 13 2018
...Tropical Systems Becoming More Threatening...
...Weather threats/highlights and Guidance
evaluation/preferences...
Tropical system activity is quickly escallating over the Atlantic
basin. The NHC shows Hurricane Beryl over the tropical Atlantic
whose forecast threatens the eastern Caribbean and vicinity, with
latter next week residual moisture possibly working into Florida.
NHC also continues to follow a disturbance off the southeastern
U.S. that offers development potential. WPC progs show a
coordinated track for this latter system with the assumption of
further development and track off the east coast. Recent UKMET
runs vanguarded the possibillity for this low to not be picked up
by nrn stream trough passage until after a period of development
in slow steering currents off the coastal Carolinas. Latest GFS
and ECMWF runs have now trended toward this idea of waiting for
mid-upper level trough energy digging through the Northeast next
midweek to interact with the system. The GFS offers a
deeper/closer to the coast track off the Eastern Seaboard than
NHC/WPC depictions, with the ECMWF/CMC further offshore.
Otherwise, an upper high will dominate much of the lower 48 next
week. Mean troughs extending down into the Northwest and Northeast
flatten then re-amplify again along the US/Canadian border.
Heights will become above average coast to coast which supports
near to above average temperatures over most areas outside the
southern tier. A moderating front in the east will dissipate next
week as western North American fronts shift downstream across the
northern plains, Upper Midwest/Great Lakes and Northeast along
with thunderstorm focus and local severe storm threat as per SPC.
The Southwest will see enhanced monsoonal moisture around the
upper high realized as precipitation initially over the higher
terrain and then into some of the lower deserts.
The WPC medium range product suite was mainly derived from a blend
of reasonably clustered guidance from the 06 UTC GEFS mean and 00
UTC NAEFS/ECMWF ensemble means through the medium range period.
The latest individual models were also reasonably well clustered
with ensembles over land, but have been more diverse with tropical
based systems. While guidance is coming into better agreement
offshore as well, instead prefer to blend the ensemble means
everywhere and manually insert current/potential tropical systems
as per coordination between WPC and NHC.
Schichtel
WPC medium range 500 mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indexes are found at:
http://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
http://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
http://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
http://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
http://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
http://www.wpc.ncep.noaa.gov/heat_index.shtml