Scientific Forecaster Discussion
fxus63 kind 210328
Area forecast discussion
National Weather Service Indianapolis in
1128 PM EDT Fri Sep 20 2019
the aviation section has been updated below.
issued at 348 PM EDT Fri Sep 20 2019
The heat and mainly dry conditions with the exception of pop up
storms this evening and tonight will come to an end this weekend
as an upper trough and associated cold front enter the area. The
bulk of the precipitation will come on Sunday with rainfall
amounts up to the 1 to 2 inch range. In the wake of the cold
front, temperatures will cool down to more normal temperatures
with highs in the 70s and lows in the 50s before creeping up again
next weekend. Meanwhile, conditions will be dry from Monday
afternoon through Tuesday night with brief high pressure before
the next front brings more chances for showers and thunderstorms
Wednesday through Friday.
Near term /overnight/...
issued at 945 PM EDT Fri Sep 20 2019
Isolated convection over the lower Wabash valley earlier this
evening has diminished as of mid evening. Other than some leftover
stratocu and higher level cloud debris...skies were partly cloudy.
0130z temperatures were primarily in the 70s.
Overall forecast is in great shape for thew overnight with just
minor adjustments. Still monitoring the potential for a few
showers or storms to develop after midnight as a weak wave aloft
overtops the ridge and drifts across northern Indiana and into
Ohio by Saturday morning. Not overly impressed with the convective
setup overnight but cannot entirely rule out isolated showers and
storms near and after 06z...especially focused over the northeast
part of the forecast area in closest proximity to the wave aloft.
With low confidence...nudged pops down to low chance as much of
the area will remain dry. Bumped low temps up a degree or two over
much of the area based on current trends.
Zone and grid updates out.
Short term /tomorrow through Monday/...
Issued at 348 PM EDT Fri Sep 20 2019
After low chances for some morning showers and storms across the
northeasternmost County on Saturday morning, conditions will
become dry for most of Saturday. However, focus will then turn to
an approaching cold front and upper low. The effects of those
disturbances will begin late Saturday night across the northwest
counties as showers and thunderstorms increase. The bulk of the
precipitation will, however, come from Sunday afternoon through
Sunday night. Variability in models in regard to rainfall amounts
continue, but it does appear to be some measurable totals in the
1 to 3 inch rain as of now. Meanwhile, the heat will continue
through Sunday with the highs in the mid to upper 80s, but a
reprieve will arrive on Monday in the wake of the aforementioned
cold front as highs fall closer to normal in the mid to upper 70s.
The above normal overnight lows in the mid to upper 60s on
Saturday and Sunday nights will also take a dip by Monday night
with readings only in the mid 50s.
Long term (monday night through friday)...
issued at 239 PM EDT Fri Sep 20 2019
Models are close enough or uncertainty is high enough that the
National blend of models initialization was accepted for most items.
High pressure will keep Monday night into Tuesday dry.
As the upper pattern shifts from an upper trough to the north to
upper ridging trying to build in from the southeast, a front will
move into the area. There remains abundant uncertainty on where the
front will end up and on how any upper energy moving through the
flow will interact with the front Wednesday to Friday.
Left the low pops the intialization put in for Tue night into
Thursday given the uncertainty. The initialization's pops Thursday
night into Friday became unrealistic in coverage (splotchy 15
percents) so removed them for now. Confidence is quite low.
As the upper ridge begins to influence the area by Friday,
temperatures will rebound into the 80s most areas.
Aviation /discussion for 210600z taf issuance/...
issued at 1128 PM EDT Fri Sep 20 2019
VFR conditions expected through the forecast period.
Quiet weather is expected overnight and into Saturday as ridging at
the surface and aloft attempts to strengthen slightly over the area.
A small threat exists for isolated convection overnight but it
should remain northeast of the terminals. With a frontal boundary
aligning northwest of the region Saturday...modest surface pressure
gradient will enable gusty southwest flow during the afternoon. Cu
will develop again during the afternoon with potential for an
increase in mid and high level clouds by late day into Saturday
evening from rain and storms to the northwest of the region.