Valparaiso, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

709
FXUS63 KLOT 022047
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
347 PM CDT Wed Apr 2 2025

.KEY MESSAGES...

- The threat for severe weather continues through early this
  evening, roughly south of a Streator IL to Gary IN line, and
  particularly from southwest Ford County to far southeast
  Porter County IN and points south and southeast. Severe
  threats will include damaging wind gusts, tornadoes, and
  at least isolated instances of large hail.

- For locations off to the north and northwest, the severe
  weather threat is lower, with a localized flooding threat
  into the Chicago metro.

- Strong south winds late this afternoon through early evening,
  especially south of I-80 where gusts in excess of 45 mph are
  probable.

- Periods of rain, possibly heavy, late Friday afternoon into
  Saturday morning, with possible localized flooding south of
  I-80.

&&

.MESOSCALE...
Issued at 347 PM CDT Wed Apr 2 2025

We don`t have much to add from the previous discussion (below)
regarding the highly favorable environment for severe weather
lifting northward with a strong warm front. Within the Tornado
Watch just issued, the highest relative tornado threat looks to
be near and south of the Kankakee River. With that said, given
the recently more rapid northward progression of the warm front,
opted to include Grundy, Will, Lake IN, and Porter Counties in
the watch.

Currently supercellular storm mode may potentially trend more
linear with time toward early evening as storms track to the
northeast at 60-70 mph. During at least semi-discrete mode,
main severe hazards will be tornadoes and large hail. Given the
parallel orientation of the deep layer bulk shear vector with
the convection stretching back to west of St. Louis, there may
tend to be evolution into a QLCS with embedded supercell/mesovortex
mode. The volatile environment in place in the warm sector up
to the vicinity of the warm front will likely present a threat
for longer tracked, potentially stronger embedded tornadoes.
This would particularly be the case in closer proximity to the
warm front where streamwise vorticity ingestion will be
enhanced.

Castro

PREVIOUS MESOSCALE UPDATE...
Issued at 150 PM CDT Wed Apr 2 2025

The surface warm front has been able to recently reach roughly
the US Highway 24 corridor, though with a better northward push
into Newton and Jasper Counties. The airmass south of the front
is exceptionally warm and moist for early April with temperatures
into the low-mid 70s and dew points into the 60s. Despite
extensive cloud cover, latest mesoanalysis is indicating 1k J/kg
or more of minimally capped MLCAPE. Extreme low-level
shear/helicity and 0-3km MLCAPE increasing to upwards of 100
J/kg owing to the unseasonably moist airmass in the warm sector
have contributed to an exceptionally favorable environment for
tornadoes, some significant, of course contingent upon intense
convection.

A few low-topped supercells were able to develop right near the
front but have since mostly crossed north of the front as they
race northeast at over 70 mph (exiting Jasper County before the
top of the hour). It`s tough to be very specific on the timing
of new convective initiation, though generally speaking, chances
should uptick after 4pm given most recent radar trends and high
resolution ensemble system WarnOnForecast (WoFS) runs. The
potential higher end severe threat area (damaging wind and
tornadoes) dovetails fairly well with the current level 3 of 5
(enhanced risk) threat delineation in the SPC Outlook.

Castro

&&

.DISCUSSION...
Issued at 319 PM CDT Wed Apr 2 2025

Through Friday Afternoon:

The threat of showers and thunderstorms will come to an end
from west to east following a cold frontal passage this evening.
For more on the ongoing threat for severe thunderstorms,
reference the meso discussions above.

Meanwhile, the threat of strong southerly wind gusts up to 45
mph will continue in the going wind advisory through early this
evening. Accordingly, no changes are planned to the wind
advisory headline. The ongoing convection has acted to slow the
northward progression of the warm front for the last few hours,
and hence has kept the stronger southerly winds largely south of
the area. This should change within the next couple of hours,
however, as the warm front begins to surge northward in response
to the parent surface low quickly shifting northward into the
Upper Midwest. As it does so, expect the strong gusty southerly
winds to develop across the advisory area. There could even end
up being a short hour or two period early this evening where
winds gust 40-45 mph in areas north of the going advisory
(including the Chicago metro area) before the cold front shifts
across the area. Also, expect temperatures to jump up into the
60s across much of northern IL for a period early this evening
following the warm frontal passage.

Winds will turn westerly this evening following the quick
eastward passage of the cold front. While wind speeds tonight in
the wake of the cold front will not be nearly as strong as the
southerly winds ahead of the front, gusty westerly winds up to
around 30 mph are expected at times overnight into Thursday
morning before gusts ease Thursday afternoon. Expect a
seasonably mild day under mostly cloudy skies Thursday, with
highs ranging from the upper 50s to the lower 60s.

The surface cold front that shifts across our area this evening
will stall out across the Ohio Valley on Thursday into early
Friday. This front will become the primary focus for several
additional rounds of heavy rain producing showers and
thunderstorms Thursday through Friday as deep Gulf moisture
continually feeds into this frontal zone. Fortunately, a
majority of this heavy rain is expected to fall south of our
area across southern parts of IL and IN through Friday morning.
Accordingly, most of our area is likely to remain dry Thursday
through at least early Friday afternoon. The only exception
being a low chance (20-30%) for a few light showers well south
of I-80 Thursday afternoon and evening.

KJB

Friday Afternoon through Wednesday:

The threat for rain (and even some storms) will return to our
area late Friday through Saturday. This as several low amplitude
impulses begin to eject northeastward out of a potent
mid/upper-level trough/low shifting across the Desert
Southwest. Each impulse is expected to drive a wave of surface
low pressure northeastward along the remnant frontal boundary to
our south through the weekend. The first such wave will track
into central parts of IN Friday night into early Saturday
morning. As it does, it will aid in the northward push of
moisture over the surface frontal boundary, thus supporting
increasing rain (and perhaps a few embedded thunderstorms)
chances across much of our area Friday afternoon into Saturday.
Rain chances will peak in the 80 to 100% range areawide Friday
night, though the heaviest rainfall (1"+) is currently favored
to fall south of I-80 into Saturday morning.

Our next wave of low pressure is expected to track farther to
our southeast late Saturday into early Sunday morning. It
appears this wave may remain far enough to our southeast to keep
the threat for the next wave of rain south and east of our area
late Saturday into early Sunday. Accordingly, aside from some
low chance PoPs into Sunday morning (mainly south of I-80),
drier weather is favored for the end of the weekend.

Temperatures through the weekend will cool down as northerly
flow dominates. Daytime highs will generally be in the lower
50s, though even cooler conditions in the lower to mid 40s can
be expected near the lake due to the onshore wind component. A
period of even colder (below average) weather is then likely to
shift into the area for Monday as a stout northern stream trough
digs in over the Great Lakes. High temperatures will likely
remain in the lower 40s for Monday, and the potential exists for
periods of snow showers during the day. Conditions should then
gradually moderate into the middle of next week following the
eastward passage of a surface high.

KJB

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1255 PM CDT Wed Apr 2 2025

Key Aviation Messages for the current TAF period:

- Waves of showers and scattered thunderstorms through the
  afternoon

- MVFR conditions mainly driven by lower visibility from rain
  showers

- Easterly winds will shift southerly as a warm front moves
  through with strong gusts around 30 knots possible

- Chances for rain diminish this evening as winds become
  westerly behind a cold front

At the moment this discussion was sent, most of the lightning
activity has moved east of area terminals, with lingering
showery activity in its wake. Conditions remain around MVFR
conditions, but mainly due to lower vis with the showers rather
than the cigs. Winds remain out of the east ahead of the warm
front with occasional gusts around 20 knots. As that front
lifts (along with the timing of the next round of storms), winds
are expected to swing to the south and increase.

The next complex of thunderstorms is moving in from the
southwest and should arrive at Chicago terminals just before 19Z
providing heavier rain with lightning, as well as lower cigs and
vis through the early afternoon. There remains lower confidence
in the severe threat, but the main hazard would be gustier
winds with the storms. Behind this thunderstorm risk, winds will
slowly become more southerly if not southwesterly with gusts to
30 knots. High res models are still suggesting one last
developing wave of showers that can move from RFD after 21Z
through the Chicago terminals by 00Z. If there was a chance for
severe weather, it would likely come with this time window for
thunderstorms at terminals. However, confidence remains low so
it was kept as a PROB30 at area terminals, though the better
chances remain around KGYY and areas to the south.

Cigs and vis will gradually improve after this boundary passes.
Drier conditions are expected behind it as winds turn to the
west. Gusts between 20 to 25 knots are expected through Thursday
morning.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory until 7 PM CDT this evening for ILZ019-ILZ021-
     ILZ023-ILZ032-ILZ033-ILZ039.

IN...Wind Advisory until 7 PM CDT /8 PM EDT/ this evening for
     INZ010-INZ019.

LM...Gale Warning until 7 PM CDT this evening for the IL and IN
     nearshore waters.

&&

$$

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