Scientific Forecaster Discussion
fxus63 kind 280221
Area forecast discussion
National Weather Service Indianapolis in
1021 PM EDT Tue Jun 27 2017
the aviation section has been updated below.
issued at 339 PM EDT Tue Jun 27 2017
Dry weather continues across Indiana Tuesday as high pressure
persists. Despite the subsidence, some diurnal cu development was
ongoing Tuesday afternoon. An upper level system situated over
the northern plains will move into the upper Midwest tonight and
will approach the Great Lakes region Wednesday and Wednesday
night. The first round of showers and thunderstorms will move into
northern Indiana early Thursday morning and will be followed by
more widespread rain Friday and Friday night. Another upper level
system will move in late Sunday into Tuesday, but with significant
model disagreement, timing for precipitation is uncertain at this
Near term /rest of tonight/...
Issued at 941 PM EDT Tue Jun 27 2017
Forecast is in good shape. Made some minor adjustments to sky and
temperatures to reflect current trends.
Previous discussion follows...
High pressure will persist across central Indiana tonight. Clear
skies, nearly calm wind, and relatively dry air will bring another
chance for near record low temperatures across the state. Any
diurnal cu currently present over the state should dissipate by
late evening. The models have had a difficult time handling this
abnormal cold pattern, so went a few degrees below consensus for
Short term /Wednesday through Friday/...
Issued at 339 PM EDT Tue Jun 27 2017
The aforementioned high pressure will steadily weaken and move east
Wednesday into Wednesday night as an upper level as an upper level
system approaches from the northwest. Timing looks to be slower
with each model run, so removed any mention for showers until
after 6z Wednesday night. Showers and thunderstorms will stay
confined to the northern half of the state Thursday and Thursday
night. Storm Prediction Center currently has a slight risk along a line just north of
Interstate 70. Winds look to be the greatest threat with 0-6km
bulk shear around 30 kts and 2000 to 3000 j/kg cape.
More widespread convection is likely Friday and Friday night as
another upper level system and surface front moves through the
area. There is still significant model inconsistency regarding
the timing of the front, but the best chances for showers and
thunderstorms look to be Friday afternoon and evening.
Temperatures and humidity will increase through the week as
northwesterly flow moves out and rich Gulf moisture moves into the
area. Temperatures will Max out in the mid 80s Thursday before
cooling into the lower 80s by Friday and into the weekend. Winds
will be southerly through the period and could become a bit gusty
across the northern counties during the afternoon Wednesday
Long term /Friday night through Tuesday/...
Issued at 231 PM EDT Tue Jun 27 2017
The long term starts with a frontal system and an upper wave
moving through the forecast area, keeping chances for showers and
thunderstorms across the area until after the front passes and the
wave moves out. By Saturday night a surface ridge moves across the
area bringing dry weather in for a bit. The next system begins
approaching Sunday afternoon/night and keeps thunderstorm chances
in through Tuesday. Model variability during that time keeps
confidence lower average and kept chances pops going through that
time but eliminated likelies. Confidence is moderately high that
thunderstorms will occur sometime between Saturday and Tuesday but
confidence for any particular 12 hour period is low.
Temperatures should run near normal for this time of year, with
highs in the mid 80s and lows in the 60s.
Aviation (discussion for the 280300z taf update)...
issued at 1021 PM EDT Tue Jun 27 2017
No changes needed to kind taf.
Previous discussion follows...
VFR conditions expected through the period.
Light winds overnight will become south Wednesday morning and
increase into the 10-15kt range. Gusts over 20kt are possible during
Some high clouds overnight will give way to few to scattered cumulus