509
FXUS63 KIWX 091913
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
313 PM EDT Sun Mar 9 2025

.KEY MESSAGES...

- Warming trend early this week, turning slightly cooler Tuesday
  and Wednesday before much above normal temperatures return for
  Thursday through Saturday.

- Mainly dry conditions through the middle of the week with just a
  slight chance of showers on Thursday.

- Showers and isolated to scattered thunderstorms may arrive as
  early as Friday night and persist through Saturday. Windy
  conditions may accompany this system next weekend also.

&&

.DISCUSSION...
Issued at 310 PM EDT Sun Mar 9 2025

Quiet weather will persist into the early parts of this week with a
continued moderation in temperatures heading into Monday.

Local area remains affected by northwest flow northern stream
portion of the split flow pattern. This westerly flow regime
will support continued warm advection into Tuesday morning. A
few degrees of moderation in low temperatures is expected
tonight given the past 24 hours of warm advection and
maintenance of some westerly low level gradient.

Little change in synoptic pattern into Monday as broader upper level
short wave across southwest Canada begins to dampen western CONUS
upper ridge. Persistent low level warm advection continues Monday,
with primary low level thermal ridge ahead of this short wave
shifting across southern Great Lakes and Ohio Valley by 12Z Tuesday
morning. Timing of fropa still supports the overall cooling
trend of previous forecasts past several cycles, with Tuesday PM
falling temperatures expected especially northwest half. Cold
advection is fairly shallow with this frontal boundary, but
gusts to 20 to 25 mph still appear possible during the day.
Lakefront areas may drop into the mid-upper 30s across southwest
Lower Michigan while far southeast locations remain in the
upper 50s in the afternoon.

Passage of the southern Canadian wave and resultant lower
amplitude flow will result in low level baroclinic zone
stalling across the Mid MS River Valley into the eastern Great
Lakes for Wednesday. Cooler conditions, but still above normal,
are expected for Wednesday.

For Thursday, forcing from southern stream upper trough should
remain primarily south across the Lower MS Valley, but as large
scale flow amplification commences in response to digging western
CONUS upper trough, guidance hints at some mid level reflection of
southern stream wave getting ingested northeast into the Ohio
Valley. The combination of this weak forcing, stalled frontal
boundary, and weak moisture transport into the Ohio Valley still
argues for maintaining forecast continuity with slight chance rain
shower PoPs Thursday. Some modest mid level lapse rates are likely
to advect into the area Wednesday night into Thursday which could
contribute to some weak sfc based instability Thursday
afternoon.

Warmest conditions of this forecast period are still expected in the
Thursday-Saturday period as large scale flow amplification allows
strong southerly flow regime to setup. A more stable longwave
pattern appears to try and take hold toward weekend which may result
in slower breakdown of eastern CONUS ridge, and north-northeast
track of strong upper height minimum emerging out of the
Rockies. It still appears as though rapidly deepening/occluding
system should occur across Central Plains Friday with likely
shower PoPs maintained in pre-frontal/warm-frontal forcing
portion of this system. This evolution should tend to favor
greatest strong storm potential back to the west across the Mid
MS River Valley on Friday afternoon/early evening. However,
given strength of low level jet and strong mid/upper level
forcing ejecting north may eventually need to monitor potential
of some gusty showers and storms Friday night. A mid level dry
slot should punch into the region late Friday night into early
Saturday before secondary upper wave induces larger scale
frontal response on Saturday. Still some question as to favored
areas of heavier rainfall on Saturday given uncertainty in
track/strength of secondary upper wave, frontal timing, and
effects from dry slot. Will keep broadbrush likely-categorical
PoPs through the Friday night through the Saturday evening
period. Cooler conditions build in for second half of next
weekend, but still at or just above normal for mid March.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1236 PM EDT Sun Mar 9 2025

No changes to the TAFs with this afternoon issuance. High pressure
centered over the mid-Mississippi valley assures VFR conditions
through the TAF period. Only noteworthy items is the wind speed
decreases to about 5-7kts overnight then increases again toward
10kts midday Monday.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Marsili
AVIATION...Brown