River Flood Warning 37, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
856 AM EDT Fri Mar 24 2023

.SYNOPSIS...
Issued at 400 AM EDT Fri Mar 24 2023

Widespread rain returns to the area tonight with a half inch to one
inch for most locations. Rain tapers through the day Saturday but it
will be windy with gusts near 50 mph likely south of highway 24.
Quiet weather returns for Sunday but more light rain or snow is
possible Sunday night into Monday.

&&

.UPDATE...
Issued at 847 AM EDT Fri Mar 24 2023

Quick forecast update to remove measurable precip from the far
S/SE through at least 18Z.

Radar mosaic showing large area of rain had pushed well south of
the area into southern IN and OH. Timing of the return of the
rainfall tonight is a bit suspect as well as the main surface low
will be in the process of deepening and just entering southern MO
at 00Z Sat. WAA shield of rain should extend north well ahead of
the low and although rain has been pushed well south, ACARS
sounding shows plenty of saturation below 850 mb to allow the
rain to quickly restart once better lift arrives. May need to make
further adjustments to the pops for this afternoon, but will wait
for the 12Z suite of models to start to trickle in and monitor
upstream trends.

&&

.SHORT TERM...(Today and Tonight)
Issued at 400 AM EDT Fri Mar 24 2023

Much of the CWA will remain dry today as we await the NE ejection of
mid/upper trough currently scraping the US/Mexico border. A few
light showers are clipping our far S/SE zones early this morning as
a modest vorticity shred moves along the Ohio Valley baroclinic
zone. This activity will shift south by mid-late morning though as
this weak forcing exits and high pressure nudges into the area from
the N/NE. Anticipate primarily dry conditions through 00Z though
can't rule out an isolated sprinkle in our southern zones during the
late afternoon. Light ENE low level flow will maintain cool
conditions particularly in our far east downwind of Lake Erie.
Anticipate highs generally in the mid/upper 40s.

Main forecast challenge for tonight will be timing and evolution of
heaviest rain. Negatively tilted trough with good upper level
support for ascent will yield a strengthening surface low as it
lifts into the Great Lakes. There is a corresponding strong LLJ with
good moisture transport into the Ohio Valley. The main question is
where exactly will the heaviest rain track. There is a strong signal
in much of the latest hi-res guidance that deep convection over
TN/KY will rob better moisture transport into our area. Several HREF
members support this idea with mainly lower resolution models
(particularly the 12km NAM) suggesting less convection over KY
allowing heavy rain in our SE CWA tonight. Preference lies with hi-
res CAM's at this point. That is not to say we won't get any rain
but do anticipate the heaviest rain will remain to our south. Best
chances for heavier rain will probably be in our NW zones more
toward Sat morning as primary PV anomaly and deformation zone move
through the area. Have therefore massaged PoP's and QPF accordingly
with a later arrival, lower amounts SE, and slightly higher amounts
NW. Some minor river flooding is certainly likely but overall
flooding impacts are expected to remain low and will hold off on any
watch issuance.

&&

.LONG TERM...(Saturday through Thursday)
Issued at 400 AM EDT Fri Mar 24 2023

Some light rain will continue in our north on Sat morning and a few
showers are possible everywhere through the day but general trend
will be for drier conditions as the day progresses. Main weather
concern for Sat will be gusty winds as strengthening surface low
lifts into the eastern Great Lakes and places our CWA in cold/dry
air advection wing. Best chances for 40+ kt gusts will be in our SE
late morning into midday as dry slot moves through and mixing
heights increase. Looks like a solid advisory with some nonzero
chance for a few peak gusts to exceed 50 kt in our far SE but
confidence is too low for a high wind watch and it is too early for
an advisory. There is also much lower wind potential in our NW so it
will be difficult to decide where exactly to draw the line. There
may also be a few snowflakes mixing in at times Sat...particularly
by late afternoon in our northern zones. Little/no accumulation or
impacts anticipated though.

Rest of the long term is relatively quiet but we do have several
weak systems to contend with. The first arrives Sunday night into
Monday with a weak shortwave and some minor left exit jet support.
Will have to keep an eye on thermal profiles overnight as there is
some potential for snow especially in our N/NE zones. Another weak
shortwave brings some low potential for light precip early Tue. The
slow approach of a more substantial trough late next week will also
bring increasing rain chances Thu into Fri. Temps remain seasonable
through the period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 629 AM EDT Fri Mar 24 2023

A boundary remains entrenched across our south during this forecast
period. Rain was passing by to the south of the forecast area and
looks to continue to remain south of them as the boundary does look
to take a slight southward shift allowing drier air to filter in on
the northern side through the bulk of the period. NAM-based guidance
appears to indicate that as early as around 21z could be the first
instance of rain arriving at FWA, but will continue holding off the
arrival of the rain until at least after 00z for this forecast
issuance.

Flight condition-wise, an area of low to mid level warm air advection
was moving west to east in easterly winds on the northern side of
waves moving northeastward on the aforementioned boundary. This
allows CIGs to drop into MVFR threshold and will continue into mid
morning for SBN and drop off within the couple hours or so for FWA.
While models indicate SBN moderates back to VFR during the morning
time, FWA takes longer to do so, but think it eventually does
moderate into VFR mid to later morning. Once the rain arrives this
evening, both SBN and FWA will trend back toward low MVFR conditions
and, at least FWA, likely flirts with IFR to end the period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

UPDATE...Fisher
SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Roller

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Hazardous Weather Outlook
National Weather Service Northern Indiana
424 AM EDT Fri Mar 24 2023

INZ005>009-012>015-017-018-020-022>027-032>034-103-104-116-203-204-
216-MIZ078>081-177-277-OHZ001-002-004-005-015-016-024-025-250830-
Elkhart-Lagrange-Steuben-Noble-De Kalb-Starke-Pulaski-Marshall-
Fulton IN-Whitley-Allen IN-White-Cass IN-Miami-Wabash-Huntington-
Wells-Adams-Grant-Blackford-Jay-Northern La Porte-
Eastern St. Joseph IN-Northern Kosciusko-Southern La Porte-
Western St. Joseph IN-Southern Kosciusko-Cass MI-St. Joseph MI-
Branch-Hillsdale-Northern Berrien-Southern Berrien-Williams-
Fulton OH-Defiance-Henry-Paulding-Putnam-Van Wert-Allen OH-
424 AM EDT Fri Mar 24 2023 /324 AM CDT Fri Mar 24 2023/

This Hazardous Weather Outlook is for northern Indiana, southwest
Michigan and northwest Ohio.

.DAY ONE...Today and tonight.

Widespread rain up to one inch is expected tonight. This may cause
ponding of water on the roads or minor flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Winds from the southwest may gust up to 50 mph Saturday, mainly along
and east of Interstate 69.

Minor flooding is expected on some area rivers over the weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

LMZ043-046-250830-
New Buffalo MI to St Joseph MI-Michigan City IN to New Buffalo MI-
424 AM EDT Fri Mar 24 2023

This Hazardous Weather Outlook is for the nearshore waters of
southeastern Lake Michigan.

.DAY ONE...Today and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Conditions hazardous to small craft are likely Saturday.