Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 290730

Area Forecast Discussion
National Weather Service Indianapolis IN
330 AM EDT Thu Oct 29 2020

and LONG TERM Sections have been updated below.


Issued at 245 AM EDT Thu Oct 29 2020

 - Widespread rain and ponding of water on some roads and low-lying
   areas today, slowing diminishing this afternoon
 - Improved conditions Friday and Saturday
 - Cold front Sunday with gusty winds; cold Sunday night (20s)
 - Milder weather by mid next week


.NEAR TERM /Today/...

Issued at 310 AM EDT Thu Oct 29 2020

Zeta continues to move NE through the Dixie states early this
morning, while a deep upper low moves east across the southern
Plains. A large area of deep moisture and lift exists north and east
of these systems, and has resulted in widespread rain across the OH
Valley, including central IN.

Currently, and as expected, the heaviest rain has been occurring
over our southern counties, where the Flood Watch remains in effect.
In this area, model spatial-height cross-sections confirm that a
deep frontogenetically-forced zone is present, resulting in strong
isentropic lift as a robust low-level jet (40-50 kts) over TN and KY
impinges and converges on a relatively tight west-east thermal
gradient near the OH River just above the stable boundary layer.
Aloft, negative equivalent potential vorticity (EPV) continues to be
present, suggesting the presence of less stable air aloft (CSI)
which helps to promote greater lift for the same amount of forcing.
In fact, latest GOES-16 IR imagery shows enhancement of cloud tops
over SE MO and southern IL at this time, suggestive of some
convective-like (no thunder/lightning) elements embedded within the
rain. The trajectory/movement of these elements in the deep S to SW
flow aloft suggests these will move across our southern counties
through the early morning hours. Already, dual pol/MRMS radar
rainfall estimates indicate close to an inch at this time in our
most southern row of counties from southern Knox to Jennings
counties. With the additional rain and embedded convective elements
still to come, another 1-2 inches are a good bet. Thus, the current
Flood Watch looks good spatially and continues through its 18 UTC (2
pm EDT) expiration. Will have to monitor for the possibility of
at least minor flooding, particularly roads, low-lying areas, and
creeks this morning. With the rain occurring in darkness, use extra
caution if driving and do not drive into any flooded locations.

This area of strong frontogenetical forcing associated with the
primary warm conveyer belt will head off to our east later this
morning. A relative lull in rainfall could occur, with still with at
least light rain expected. However, as the upper low passes to our
south, an elongated stretching deformation axis aloft to its north
will pass across much of central IN later today resulting in
additional banded moderate precip. Fortunately, the band will be
progressive and should move out of central IN this evening, ending
last over our southeastern counties. With low clouds and rain today,
high temperatures will not rise much from morning lows, peaking in
the upper 40s and lower 50s.


.SHORT TERM /Tonight and Friday/...

Issued at 320 AM EDT Thu Oct 29 2020

The weather quiets down considerably tonight. After lingering rain
across southern/southeastern counties this evening, dry weather will
prevail tonight and continue Friday. Clouds should linger much of
the night (some breaks possible in our northern and western
counties) and into the morning hours Friday, but clearing will
set in during the day. After morning lows in the 30s, afternoon
temps will remain cool, rebounding into the upper 40s and lower


.LONG TERM /Friday Night through Wednesday/...

Issued at 315 AM EDT Thu Oct 29 2020

High pressure will be building into the region for Friday night into
Saturday helping warm the surface through adiabatic warming. Expect
dry conditions with afternoon highs in the upper 50s. With a strong
upper level jet, most of the CONUS has been in a fairly active
pattern over the last couple weeks. This looks to continue on Sunday
as a deepening surface low passes to the north. Blocked Gulf
moisture for much of the day Sunday will inhibit cloud growth.
Current models show RH values less than 50% within notable vertical
lift, which is not be sufficient enough for rain formation. The more
tangible threat on Sunday will be enhanced winds, due to a
tightening low level pressure gradient and surface front passage.
Strong dry, cold air behind the disturbance will also help promote
wind gusts. Current expectations are for winds to be sustained out
of the NW between 15 and 20 mph. 850mb winds look to be around
40 MPH, and with efficient mixing, a good percentage of this
energy should be able to reach the surface. Locations north of
I-70 will be in the most prominent zone for high winds.

Strong CAA behind the low will allow for temperatures to plummet
Sunday night. Current expectation are for highs to be in the upper
20s A broad ridge will encompass most of the CONUS for the rest of
the long term. This should lead to subtle temperatures increases
throughout the week along with calm and dry conditions. The warmest
day in the long term should be Wednesday as the ridge axis and more
substantial subsidence nears. Highs on Wednesday look to be in the
mid 60s.


.AVIATION /Discussion for the 290600Z Tafs/...

Issued at 1149 PM EDT Wed Oct 28 2020

/Discussion for the 290000Z Tafs/...

Issued at 734 PM EDT Wed Oct 28 2020

IMPACTS: At HUF...BMG and IND...ceilings will continue to
deteriorate toward IFR Overnight as rain from Zeta moves arrives
along with the frontal boundary to the south arriving  KLAF may
be the exception and remain in VFR through much or all of the rain

DISCUSSION: Remnants from Zeta along with a frontal boundary in
place near the Ohio River will lead to rain overnight along with
deteriorating flying conditions. Strong lift as seen within the
time heights and deep saturation shown by the forecast soundings
suggest abundant precip and low Cigs arriving particularly on the
northern side of the frontal boundary. Radar Mosaics show
abundant precip over KY streaming across southern Indiana and
pushing northward toward Central Indiana. Improvement toward VFR
will be expected from NW to SE on Thursday afternoon...with VFR
expected after 300000Z.

CONFIDENCE: High confidence in flying conditions deteriorating to
IFR and worse late tonight. IFR conditions will persist through
at least 291500Z. Confidence not as high on flying conditions at
KLAF, but feel will be mostly VFR there.


Flood Watch until 2 PM EDT this afternoon for INZ061>065-067>072.



LONG TERM....Updike
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