IWX issues Area Forecast Discussion (AFD) at Sep 5, 12:54 PM EDT421
FXUS63 KIWX 051654
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1254 PM EDT Thu Sep 5 2024
.KEY MESSAGES...
- Mainly dry and very warm today with highs in the 80s to near
90. An isolated shower possible in a few spots, but most areas
to remain dry.
- Scattered to numerous showers Friday. Lake showers Saturday ending
Saturday night.
- Turning much cooler this weekend with highs in the 60s to around
70.
- Much warmer next week with the rapid onset of drought conditions.
Temperatures will rise rising well above normal in the 80s
next week.
&&
.UPDATE...
Issued at 1051 AM EDT Thu Sep 5 2024
A few isolated light showers have developed this morning at
leading edge of low level theta-e gradient. This pocket of
higher low level theta-e air and very weak short waves moving in
from the west from the Plains via a mid-upper deformation flow
could be enough for a few isolated showers into this afternoon.
Some question as to magnitude of sfc instability during peak
mixing today, with the possibility that low level mixing could
limit instability progs enough to prevent any isolated showers
after 18Z. Best chance of an isolated shower this afternoon may
be along and east of I-69 corridor which could be near
interface of this moisture gradient.
&&
.DISCUSSION...
Issued at 245 AM EDT Thu Sep 5 2024
An expansive surface high pressure area was east of the region
over the Eastern Seaboard and was keeping a flow of very warm
air well to the west of the high into the forecast area. For the
third in as many days, shallow but chilly air near the ground
early this morning will rapidly mix out allowing afternoon
temperatures to soar well into the 80s to around 90 in spots
(especially northwest Ohio). Flash Drought conditions over the
past 3 days have been continuing to intensify, increasing
feedback (superadiabatic lapse rate off the ground).
A large upper low will amplify into the upper Great Lakes region
Friday and be accompanied by scattered to numerous showers
Friday transitioning to lake effect showers Saturday. Strong low
level flow is expected to cause dangerous swimming conditions
along the southeast shore of Lake Michigan Friday and Saturday.
Have favored the GFS which has kept very limited synoptic
precipitation Friday given very brief saturation per 305K and
310K surfaces. The synoptic showery pattern will transition to
a relatively brief lake effect event near and downstream from
Lake Michigan from early Saturday into early Saturday night.
The GFS and ECMWF continue into reasonable agreement with with mass
fields and great agreement with 850 mb temperatures falling close to
+2C rendering delta T values close to 20C given very warm Lake
Michigan water temperatures. Have kept shower chances downstream
of Lake Michigan Friday night into early Saturday night given
the low level GFS fetch, delta T values (near 22C) and massive
moisture flux out of a lake with water temperatures >= 24C per
GLERL. The latest CAMs and other high resolution models appear
to have a much better handle on the finer features including the
multiple lake bands Friday night and early Saturday. Overall,
rainfall through the weekend should be very limited and is not
expected to do much to stave of the flash drought developing
over much of the area. All indications are the drought
conditions will continue to intensify next week as dry weather
prevails and highs rise much above normal.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1253 PM EDT Thu Sep 5 2024
A few showers have developed over northern IN on the leading edge of
a low level theta-e gradient. However, limited coverage precludes a
shra mention from being included at this time. Dry and VFR
otherwise into this evening with a sct to bkn cu field around 5
kft.
A cold front will drop southeast through KSBN overnight, and KFWA
shortly after daybreak tomorrow. Scattered showers may accompany the
frontal passage with light sw winds veering northerly. A time of
post-frontal MVFR cigs appears possible tomorrow morning, best
chances at KSBN.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
UPDATE...Marsili
DISCUSSION...Skipper
AVIATION...Steinwedel
Source:
IWX issues Area Forecast Discussion (AFD) at Sep 5, 12:54 PM EDT---------------
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