Scientific Forecaster Discussion
fxus62 krah 240148
Area forecast discussion
National Weather Service Raleigh NC
948 PM EDT sun Jul 23 2017
a Piedmont trough will extend from Virginia into South Carolina
through Tuesday. A cold front will drop south into North Carolina on
Tuesday and then stall across the region on Wednesday and Thursday.
Near term /through tonight/...
as of 945 PM Sunday...
Initial round of storms, which become cool pool dominated, have
either dissipated or moved east of the area, with only some
stratiform rain remaining east of US Highway 1. Another band of
convection that's moving east into the southern Appalachians, in
advance of the Ohio Valley shortwave, is expected to fade after
crossing the Blue Ridge after midnight. Will leave a slight chance
pop in overnight.
Widespread thunderstorms and convective outflow boundaries galore
have aided in cooling temperatures into the 70s just about
everywhere. So it will be a little cooler tonight compared to the
past two nights. Lows in the 70s.
Short term /Monday through Monday night/...
as of 145 PM Sunday...
Broad cyclonic flow will persist across the mid Atlantic and
northeast on Monday and Monday night. The upper-level trough axis
will shift east during the period, allowing a weak surface cold
front to move into central NC Monday night and then stall. Heights
at 500 hpa actually increase a bit but widespread moisture should
result in a fair amount of cloudiness, especially in the mid and
high levels. Depending on how convection evolves late tonight, some
widely scattered showers and storms may be ongoing on Monday
morning, especially across the south and east. Additional, mainly
scattered storms are apt to redevelop during the midday and
especially afternoon hours with the greatest coverage across the
southern and eastern Piedmont and in the coastal plain. More limited
coverage is expected across the western Piedmont and triad. Central
NC is outlooked in the general thunder category by Storm Prediction Center. While no
organized convection is expected, can't rule out a stronger storm
given the higher cape and slightly stronger flow.
Low-level thickness values drop about 7 to 10m across the area
compared to today which combined with the cloud cover should result
in highs about 2 to 4 degrees cooler than today but a few degrees
warmer than previously forecast for Monday. This should result in
highs in the 93 to 98 range, providing heat index values of 97-104,
close but not reaching criteria, except in an isolated spot of two.
For now, plan to hold off on any heat advisories and have
coordinated with most of our neighboring wfos, but we will be
close to the threshold and given the multiple days of of heat
issues already experienced, the mid shift will need to consider
issuing an advisory. It will remain muggy on Monday night with
lows in the 73 to 78 range. -Blaes
Long term /Tuesday through Sunday/...
as of 355 PM Sunday...
Long range guidance continues to indicate that shortwave energy will
stall over the southeast mid-week as an upper level ridge extends
eastward from the Central Plains to the Carolinas. Northwest flow aloft is
expected to strengthen over the region late this week through this
weekend as an upper level ridge amplifies over The Rockies and
shortwave energy digs southeast across the Great Lakes. At this time,
expect at or slightly below normal temperatures in association with
increased cloud cover and an increased potential for convection,
though uncertainty is greater than average in such a synoptic
Aviation /00z Monday through Friday/...
as of 835 PM Sunday...
24-hour taf period...a return to generally VFR conditions are
expected between 01z and 03z/tonight as storms end.
Looking ahead... mainly VFR conditions expected through
the work week with scattered mainly afternoon and evening
showers and thunderstorms. This could result in some
restrictions in morning fog/stratus or storms with the greatest
risk late in the work week.