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Office: IND

FXUS63 KIND 170327
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1127 PM EDT Tue Aug 16 2022

...Updated Aviation Discussion...

.Forecast Update...
Issued at 950 PM EDT Tue Aug 16 2022

Most cumulus have dissipated across central Indiana this evening,
leaving behind some passing cirrus. Some decaying clouds may rotate
southwest into the area before finally dissipating, but otherwise
mostly clear conditions will be the case.

Winds will become light across the area, and with the mostly clear
skies, expect decent cooling. Thus, have bumped down low
temperatures. Otherwise the forecast is in good shape with no
significant changes made.

&&

.Short Term...(This evening through Wednesday night)
Issued at 300 PM EDT Tue Aug 16 2022

Pleasant conditions are expected throughout the short term period
with partly cloudy skies and temperatures slightly below normal.
Northwest flow aloft continues to dominate, allowing the same
airmass over central Indiana today to stick around for much of this
week. Highs for the period will remain in the low 80s with lows near
60.

This afternoon, satellite shows daytime cumulus clouds across the
region which are expected to dissipate around sunset as daytime
heating comes to and end and the surface high further expands
south into the area. The best chance for precipitation, albeit it
is very low, for central Indiana will be this afternoon and again
tomorrow afternoon in the far eastern counties. As of this
afternoon, there is a cluster of isolated showers in western Ohio
due to cyclonic flow in the area, but those have not been showing
signs of strengthening over the past hour or so, plus the flow for
that area is more northerly, so will expect these showers to stay
out of the forecast area. For tomorrow afternoon, another weak
surface low is expected to form over eastern Ohio Valley/eastern
Kentucky, again providing some cyclonic flow for the area so at
the very least, would expect afternoon cumulus clouds to form.
But, model soundings suggest that there won't be much moisture to
work with for either period so for now, keeping PoPs out of the
forecast but will adjust in the future should it be needed. The
further expansion of the surface high and its associated
subsidence will also aid in the expected quiet weather over the
next few days.

&&

.Long Term...(Thursday through Tuesday)
Issued at 300 PM EDT Tue Aug 16 2022

Thursday through Friday...

The start of the long term will be rather quiet with broad low level
high pressure over most of the Ohio Valley. In the upper levels,
weak waves will be possible downstream of an amplified ridge, but
this should only lead to periodic upper level clouds. Temperatures
will be near seasonal both Thursday and Friday. 850mb temperatures
in the low teens (Celsius) should translate to afternoon highs in
the low 80s, given a dry PBL and ample sunshine.

Winds will gradually shift from NNE to ESE over this 48 hour stretch
as the surface high progresses eastward. Generally, winds should be
light without any substantial pressure gradients. Although,
occasional afternoon gusts up to 12kts are possible as the PBL
expands into higher winds above 1km.

Saturday through Monday night...

Unsettled weather arrives for the weekend, as a vertically stacked
low meanders eastward into the Ohio Valley. Its lack of organized
progression is likely the result of minimal upper level support. As
the upper level low dives eastward, it separates from the polar jet
resulting in 12k-14k meter flow of less than 30kts around the low;
thus disallowing strong CVA and downstream height falls. However,
by Monday, the subtropical jet should near, allowing for a smoother
eastward progression through the Ohio Valley early next week.

In the meantime (Saturday through Monday), deep moisture in
combination with periods of vertical motion should lead to scattered
rain showers. Lapse rates are not strong throughout this period (6
C/km), although there could be enough afternoon warming for brief
stretches of convection each day. The lack of shear and organized
boundaries should inhibit organized convection, with no severe
weather expected over the weekend.

By Monday night, the aforementioned low should begin to pass through,
decreasing rain chances. Rain cannot be ruled out though, as a few
ensemble members have a secondary short wave arriving Tuesday.

Temperatures should be at to below seasonal through the rest of the
long term. The increased moisture and cloud cover should inhibit
diurnal temperature gains, creating lower surface temperatures even
though the overall airmass will be relatively similar. Current
expectation are for highs near 80, with the exception of Saturday as
clouds dont arrive til after peak heating.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1127 PM EDT Tue Aug 16 2022

Impacts:

* Low possibility of fog once again overnight

Discussion:

Although the lower atmosphere is drier than Monday, cannot rule out
some ground fog forming at all but KIND given the light winds and
mostly clear skies. However, confidence in this remains too low to
put into the TAFs at this time.

More scattered cumulus will pop up on Wednesday. Wind speeds will
increase to around 10kt at times in the afternoon.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Update...50
Short Term...KH
Long Term...Updike
Aviation...50



Office: IWX FXUS63 KIWX 170125 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 925 PM EDT Tue Aug 16 2022 .SYNOPSIS... Issued at 318 PM EDT Tue Aug 16 2022 Mainly dry weather will continue through Friday with a slight warming trend for the remainder of the work week. Chances of showers and thunderstorms will increase for the weekend. && .UPDATE... Issued at 920 PM EDT Tue Aug 16 2022 Water vapor imagery this evening depicts a sheared vorticity max nosing into far northeast Indiana. and this vort max has been associated with some isolated/scattered convection at the leading edge of weak DPVA. This mid/upper level forcing has also coincided with pocket of weak sfc based instability, aided by earlier diurnal warming and better proximity to mid level cold pocket associated with broader negative upper height anomaly. Instability magnitudes will continue to rapidly wane over next few hours with an accompanying expected decrease in shower activity through 03Z. Mainly dry conditions are then expected through the remainder of the night. Cannot completely discount some patchy fog development late tonight across Lower Michigan, but confidence in occurrence/coverage remains too low to include in forecast grids at this time. && .SHORT TERM...(This Evening through Wednesday) Issued at 318 PM EDT Tue Aug 16 2022 Any showers that may be around from the weak trough dropping south should end during early evening with loss of daytime heating and departure of the wave. Can't rule out possibly lasting a bit longer into the eve per a few of the CAMs but not overly impressed with setup and even if they do precip should be quite light with vast majority of the area seeing nothing. Similar setup Wed afternoon although a bit further east and also even more sketchy if it will unfold or not as ridging gathering a stronger hold. && .LONG TERM...(Wednesday Night through Tuesday) Issued at 318 PM EDT Tue Aug 16 2022 Ridge will take hold for a few days with continued focus on sorting out timing of northern stream wave set to close off over the western Great Lakes over the weekend and shift slowly east with time. While confidence is medium to high that 1 or more periods of decent chances for showers/isolated storms will occur, the best timing remains much less confidence given lack of consistency in models over the past several days. As a result period from Sat through Sunday night will be covered in slgt chc to chc pops with continued fluctuations in best chances to persist. Even with the variations in solutions sufficient agreement that a dry forecast can be maintained for Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 813 PM EDT Tue Aug 16 2022 Weak upper level disturbances rotating around large parent upper low have combined with peak heating/weak diurnal instability for additional isolated showers and thunderstorms this afternoon, primarily NE Indiana/SC Lower Michigan. Inverted sfc trough feature and residual outflows are resulting in renewed development into early this evening across extreme NE Indiana. Best instability will remain northeast/east of terminals in closer proximity to mid level cold pool, and thus terminals should remain dry. Not expecting fog to be a big concern at this time, with best chances of notable early morning fog on Wednesday across east central Lower Michigan downwind of Lake Huron. A decent mixed layer on Wednesday should support similar NE winds to that of today in the 10 to 15 knot range. Isolated showers are possible again on Wednesday, but greatest potential appears to be east of terminals. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...Marsili SYNOPSIS...Marsili SHORT TERM...Fisher LONG TERM...Fisher AVIATION...Marsili Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana