IND issues Area Forecast Discussion (AFD) at Jul 25, 9:25 AM EDT862
FXUS63 KIND 251325 AAA
AFDIND
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
925 AM EDT Thu Jul 25 2024
.KEY MESSAGES...
- Quiet weather expected for much of central IN today, but a few
showers or storms are possible across southern portions of the
area
- Seasonable temperatures in the 80s through this weekend gradually
warming into the lower 90s next week
- Increasing threat for multiple storm clusters to impact the region
next week
&&
.FORECAST UPDATE...
Issued at 925 AM EDT Thu Jul 25 2024
Surface heating has started and is resulting in diminishing fog and
improving visibility. Ridge/trough synoptic pattern favors an
intrusion of slightly cooler and drier air into central Indiana
today. Current forecast seems to represent this air mass change
well.
In the near-term, ongoing elevated convection over west-central
Illinois is maintaining its intensity per IR satellite cloud top
temperatures as it moves southeastward, and may reach Sullivan and
Knox counties later. Its longevity is in question because, 1. the
cold pool may not be sufficiently robust, 2. downstream surface
destabilization may be minimal, and 3. the warm/moist advection at
~850-mb appears to be weaker downstream. Nevertheless, at least some
remnant convection or convective debris may be present across our
southern counties into early afternoon. We adjusted precipitation
probabilities and cloud cover slightly to account for this.
&&
.SHORT TERM (Today and tonight)...
Issued at 302 AM EDT Thu Jul 25 2024
Mostly clear skies and light winds have allowed for fog to develop
this morning across portions of central Indiana, mainly in locations
where rain fell yesterday. Surface observations have shown most areas
with visibilities around 4-7 miles for much of the night though a
few sites have dropped to 1/4 mile or less at times. Expect reductions
in visibilities to continue until daytime heating helps to quickly
mix out fog after daybreak. Current radar shows isolated showers/storms
are still ongoing across the area, mainly near or south of the I-70
corridor. This is associated with a frontal boundary which should
continue to slowly push southward today.
Quiet weather conditions are expected for much of central Indiana
today as high pressure continues to build in. Look for noticeably
lower humidity this afternoon due to drier air advecting in from the
northeast. In addition, northeasterly flow will keep temperatures a
few degrees cooler compared to yesterday for most of the area. Far
southern portions of the area are expected to be warmer and reach
the mid 80s once again with the aforementioned front not moving
through until late in the day. A few diurnal showers or storms
cannot be ruled out for these areas as well.
Surface high pressure overhead will continue to support mundane
weather overnight. Expect good radiational cooling and slightly
cooler air to continue filtering in. This should promote below
normal temperatures with forecasted lows ranging from 55-63.
&&
.LONG TERM (Friday through Wednesday)...
Issued at 302 AM EDT Thu Jul 25 2024
Ridging over the central part of the country will expand east into
the Great Lakes and Ohio Valley this weekend with dry weather and
seasonable temperatures. An upper low lifting out of Texas will
gradually become absorbed within the mean flow across the upper
Midwest by late weekend resulting in a flattening of heights across
the region and a return of rain chances as the feature passes by to
the northwest. The ridge will retrograde and refocus across the High
Plains next week...placing the Ohio Valley on the ridge periphery
and in a prime location for impacts from convective clusters.
Friday through Saturday
High pressure centered over the Great Lakes will gradually shift
east into the northeast states on Saturday. A predominant E/NE flow
will pump drier air into central Indiana with dewpoints once again
returning to more comfortable levels in the upper 50s and lower 60s
for Friday and most of the day Saturday. Return flow on the back
side of the high will begin transporting deeper moisture back north
into the Ohio and mid Mississippi Valleys late Saturday...
enabling humidity levels to start creeping back up and at least
provide a small threat for a few showers and storms to sneak into
the lower Wabash Valley late day into the evening. Highs in the
lower and mid 80s are expected for both Friday and Saturday.
Saturday Night through Wednesday
An upper low will lift out of Texas...and track through the
Missouri Valley and into the Upper Midwest for the second half of
the weekend. Deep moisture will advect north into the Ohio and
Mississippi Valleys in response to this upper wave with precip
water values surging to near 2 inches by Sunday. The presence
of an increasingly moist and unstable environment across the Ohio
Valley on Sunday will promote the development of scattered to
numerous convection.
Upper level flow will transition to a northwest flow regime as early
as Sunday night with the ridge axis recentering over the southern
Rockies and High Plains. Subtle waves drifting the flow aloft into
the early and middle part of next week will bring additional chances
for showers and storms and at least at this stage appears
increasingly supportive of multiple convective clusters tracking
from the Dakotas E/SE into the Upper Midwest...Great Lakes and Ohio
Valley. Timing and specific track of these clusters is uncertain at
this point and will be for at least the next few days. However...the
primary takeaway is that a shift back to a more active and stormy
pattern is likely for much of next week.
In addition...oppressive conditions will develop with dewpoints into
the 70s advecting into the region next week and the potential for
highs into the lower 90s on multiple days. The combination of the
heat and deep moisture will create high levels of instability for
these storm clusters to feed off with severe weather and heavy
rainfall producing localized flooding possible.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 632 AM EDT Thu Jul 25 2024
Impacts
- Patchy fog dissipating by 13Z
- VFR conditions expected through the period
Discussion:
High pressure continues to build across central Indiana as a cold
front sags southward. This has led to patchy fog development in
areas where recent rain fell on Wednesday. This fog has had little
impact at the TAF sites and should diminish by 13Z
An isolated shower or storm cannot be ruled out near HUF/BMG
today, but confidence is too low for a mention in the TAFs.
Winds will predominately be north/northeasterly and under 10 kts
through the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...BRB
SHORT TERM...Melo
LONG TERM...Ryan
AVIATION...Melo
Source:
IND issues Area Forecast Discussion (AFD) at Jul 25, 9:25 AM EDT---------------
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