Office: IND
FXUS63 KIND 282349
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
749 PM EDT Sun Apr 28 2024
.KEY MESSAGES...
- Showers and storms return to the Wabash Valley overnight.
- Warmer than normal conditions continue through the week.
- Additional thunderstorms expected Friday into Saturday.
&&
.SHORT TERM (This evening through Monday)...
Issued at 252 PM EDT Sun Apr 28 2024
GOES-16 visible loop and obs were showing filtered sunshine across
central Indiana this afternoon along with some fair weather cu. Lack
of synoptic lift and only weak instability and a mid level cap have
cap convection from going up. In addition, the southerly breeze with
gusts to near 30 knots has resulted in well above normal
temperatures in the upper 70s to lower 80s early this afternoon.
H20 vapor imagery and upper air data was showing a percent ridge of
high pressure over the Appalachians with a low spinning over
southern South Dakota and northern Minnesota. The latter feature
will move into the eastern Dakotas by Monday morning and Lake
Superior Monday evening. This will bring an associated cold front to
near a western Chicago suburb to St. Louis line Monday evening.
Sufficient instability and deep moisture combined with the
approaching system and any impulses ahead of it will bring
widespread showers to the Wabash Valley overnight and all of central
Indiana Monday. Went with 70% coverage over the Wabash Valley to 20%
or less east central tonight and 70-80% over all of central Indiana
Monday.
Ensembles 25th percentile 24 hour QPF ending 00z Tuesday for the
upper Wabash Valley is 0.25 inches and the 75th percentile near and
inch. Most other locales ranged from 0.20 inches to 0.60 inches in
the respective percentiles. This should not lead to anything more
than perhaps some brief river flooding along the lower Wabash early
next week.
The widespread cloud cover and convection should keep temperatures
down more tomorrow but with breezy southerly winds continuing, they
will still be above normal with highs in the 70s expected.
&&
.LONG TERM (Monday night through Sunday)...
Issued at 252 PM EDT Sun Apr 28 2024
Monday Night Through Wednesday.
Precipitation will quickly come to an end Monday night into early
Tuesday as the line of convection continues to weaken as it pushes
further east and away from the forcing associated with the low
pressure system that has brought severe weather to much of the
Central Plains for the last few days. This will bring a brief break
in rain chances for central Indiana through early Wednesday when the
next system looks to push through the Dakotas into the Great Lakes
region. Rainfall from this low pressure system is expected to stay
to the north and west of central Indiana, but a decaying storm
complex may linger just long enough to reach the northwestern
counties Wednesday morning, but either way some enhancement in low
and mid level clouds looks likely for much of the day Wednesday.
Thursday Through Sunday.
Forecast confidence into the second half of the work week and
weekend begins to lessen with significant model spread on the
cyclogenesis timing and location of the next system that ejects
from the Rockies with spatial differences in the order of multiple
states between the 00Z GFS and 12Z GFS. That being said, the large
scale nature of this low will be enough that there is higher
confidence in precipitation Friday into Saturday but details on the
severe potential or QPF would be more determined by the track that
the system ends up taking. Conditions then return closer to normal
in the aftermath of the late week system with low rain chances
continuing into Saturday with highs in the low 70s and lows near 50.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 747 PM EDT Sun Apr 28 2024
Impacts:
- Showers after 08z-12z, thunderstorms also possible
- MVFR and very brief IFR conditions possible in convection; MVFR
CIGs tomorrow
- Non-convective low level wind shear 06z-10z
Discussion:
The terminals will start off with VFR flying conditions but then
convection will move in from the west toward daybreak as a cold
front approaches. Thunder will also be possible along with MVFR and
brief IFR conditions. Most likely location for thunder will be at
KLAF between 07-12Z. Periodic showers are expected to continue
tomorrow. More detailed precipitation timing/intensity will be added
in later issuances as confidence increases.
Non-convective low level wind shear will be possible 08z-12z as a 40
knot low level jet moves across, and the near surface calms
associated with cooling. In addition, southerly winds will gusts to
25 knots for a few more hours tonight and then return once again
tomorrow morning.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...MK
LONG TERM...White
AVIATION...Updike
Office: IWX
FXUS63 KIWX 281908
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
308 PM EDT Sun Apr 28 2024
.KEY MESSAGES...
- Showers and some thunderstorms will be possible this evening
into early Monday and again Monday afternoon with gusty winds
and heavy rain being the main threats.
- Additional chances for showers and thunderstorms expected
during mid to late week period next week.
- Warm with highs in the 70s through Friday with 80s also
possible on Thursday.
&&
.DISCUSSION...
Issued at 254 PM EDT Sun Apr 28 2024
The upper low pressure system across the Upper Mississippi Valley
moves northeast into Canada this evening through Monday night.
During which time, it'll push its moisture stream into the forecast
area tonight. After an afternoon of mostly dry weather, chances for
rain are expected to increase west of IN-31 as it moves east.
However, the surface convergence breaks down, instability only
achieves 500 J/kg of energy, and precipitation amounts in
models lower despite continued push of 1 to 1.5 inch PWATs (1 to
3 SDs above normal) along with 30 kts of effective shear into
the area. As such, will look to keep likely PoPs at best. Then,
as the moisture stream slides east on Monday, the area with the
best chance to see any stronger storms appears to be east of
IN-15 and perhaps even as far east as east of I-69. The 7 C/km
mid level lapse rates depart the area before the afternoon, but
there is some maintenance of the 30 kts of effective shear and
500 J/kg MUCAPE so perhaps a damaging wind gust could be had in
the moist environment. Shear appears to have some tendency of
both boundary-parallel and -perpendicular flow owing to
individual cells and perhaps some linear segments as well. With
the MBE vectors going into the inner circle perhaps there could
be some back building or slow moving cells to allow for a heavy
rain allotment with its convective component. Upper divergence
appears to return to southeast after 00z Monday night, which
could also support the heavy rain component. The moisture stream
slides out of the area for Tuesday allowing for a drier day
with sunshine to be observed, especially during the afternoon
for eastern areas. Highs still reside in the 70s Monday and
Tuesday.
Tuesday night into Wednesday morning, a deepening progressive, but
slightly negatively tilted area of vorticity swings into the
Northern Great Lakes, forcing dissipates as precipitation approaches
from the west, so will continue with the dry forecast for Wednesday.
Additional ridging continues to build in the southeast CONUS
Wednesday through Thursday night continuing the dry streak for
the area. It won't be until Friday that we have another chance
to see more rain as a cold front comes through. Timing is in
question especially as it pertains to if we can receive a
convective component. Next weekend looks cooler with highs in
the 60s. Saturday leans drier than Sunday, but Sunday's chance
for rain is on the low side as well.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 114 PM EDT Sun Apr 28 2024
Dry conditions should hold across northern Indiana through much
of the night with some renewed chances of rain across northwest
Indiana into southwest Lower Michigan by early Monday morning.
The primary aviation weather concern this afternoon is the
continued strong winds. Diurnal mixing will continue to promote
some southwest gusts to around 30 knots through the remainder
of the afternoon, with these gusts tapering sharply toward 23Z.
A modest gradient will persist overnight that will keep south
winds up around 10 knots through the night. Large scale support
for showers and thunderstorms through this evening will remain
displaced well to the west across the Lower/Mid MS Rvr valley.
As the large scale trough shifts east overnight and an upper jet
streak lifts through downstream portion of this trough, would
expect better forcing to shift far enough east to bring rain
shower chances into NW Indiana late tonight. Confidence as far
east as KSBN is somewhat lower and will hold with VCSH mention
through Monday morning until better timing can be attained with
what should be a weakening line of showers and embedded storms.
Some brief MVFR cigs are possible NW Indiana after daybreak
Monday, but primarily VFR conditions should hold. A narrow
window of very marginal LLWS criteria is possible later tonight
ahead of the cold front, but this looks quite marginal in nature
and confidence remains low in meeting this criteria.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Roller
AVIATION...Marsili
