IND issues Area Forecast Discussion (AFD) at May 3, 1:45 PM EDT408
FXUS63 KIND 031745
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
145 PM EDT Sat May 3 2025
.KEY MESSAGES...
- Showers will continue at times through tonight, and some locally
heavy rain is possible southwest
- Near to below normal temperatures (especially through Monday), and
frequently dreary and damp conditions through the next week
&&
.FORECAST UPDATE...
Issued at 1048 AM EDT Sat May 3 2025
Main focus with this morning's update is to add more detail to the
precipitation forecast, increasing chances for southwest, western,
and south central Indiana and decreasing rain chances north of I-70.
Satellite imagery shows a developing cut off mid and upper level low
over Missouri while a strong south-north jet extends from the Gulf
Coast to Ohio to Ontario, which will push eastward today and
basically disconnect from the cut off low. This low is expected to
meander through the Ohio Valley over the next several days keeping
widespread clouds and showers around. Satellite and radar imagery
show an area of showers developing over Southern Illinois just ahead
of the low and associated trough axis within an area of enhanced
lift. Hi-res guidance has this area of showers expanding and pushing
into southwest and west-central Indiana later today, so have
increased PoPs across this area. More isolated to scattered showers
exist further north and east, including the Indy Metro. Not
expecting a washout for many areas, with the exception of Southwest
and Western Indiana where more widespread showers are located.
Forecast soundings indicate steepening mid and upper level lapse
rates due to a cooling atmospheric profile, potentially leading to a
few lightning strikes along and south of I-70 this afternoon. Took
out any thunder mention for Indianapolis and points northward as the
profile will likely remain stable enough to inhibit lightning.
Since this cut off low will meander through the area with little
forcing, lower confidence exists in where the areas of greater
shower activity could be located as guidance performs rather poorly
in these types of set ups. Current thinking is that more widespread
and heavier showers will slowly push north and east towards the Indy
Metro later this evening and tonight.
Overall rainfall amounts may vary greatly across Central Indiana
with southwestern portions of the state receiving 3/4th inch of rain
to possible over an inch, while North of I-70 and into North Central
Indiana may observe considerably less ranging from a tenth to a
half inch over the next 24 hours.
&&
.SHORT TERM (Today and tonight)...
Issued at 228 AM EDT Sat May 3 2025
Rain will continue at times across central Indiana throughout the
short term period as an upper level low sets up across the area.
Locally heavy rain is possible across southwest portions of the area.
Early This Morning...
As a weak wave of low pressure rides along a boundary to the
southeast of central Indiana, scattered to perhaps numerous showers
will be across mainly the southeastern half of the area. Coverage
will diminish some as the low moves east.
This Morning through Mid-Afternoon...
Scattered to numerous showers will return to mainly southern and
eastern portions of the area as additional rounds of forcing move
through. Cannot rule out some showers northwest though with some
weak troughing noted at the surface. Will have lower PoPs northwest
with higher PoPs at times farther south and east.
Some weak instability may allow an isolated thunderstorm to develop,
but severe weather is not expected.
Clouds will help keep temperatures in the lower to middle 60s for
the most part. If some sun does break through, readings in the upper
60s are possible.
Late Afternoon and Tonight...
As the upper low moves southeast into western Kentucky, forcing will
increase. Plentiful moisture will remain across the area. Will have
high PoPs most areas at some point during this period. Instability
will be enough for the potential of an isolated thunderstorm late
this afternoon, but then instability diminishes into the night.
850mb winds increase from the northeast overnight, increasing
convergence across the southwest portions of the forecast area. A
surface pressure trough will also linger in this area. This leads to
the potential of repeated development of showers over the same area.
HREF local probability matched mean QPF forecasts do show the
potential for locally heavy rain focused on the southwest forecast
area. Will mention the threat of locally heavy rain and will
continue to monitor.
Lows will be in the 40s.
&&
.LONG TERM (Sunday through Friday)...
Issued at 228 AM EDT Sat May 3 2025
The long term period will be characterized by a stagnant and
blocky pattern featuring a couple of cutoff upper level low pressure
centers, which will impact the area over the weekend into early next
week, with the second following mid to late week.
This will lead to seasonably cool and dreary conditions through the
weekend into Monday, with near constant chances for showers. As the
first low departs, a break in rain chances is possible sometime
around Tuesday night give or take before the threat for showers
returns Wednesday onward.
An isolated thunderstorm cannot be completely ruled out during peak
heating each day, but chances at this point appear too low for
inclusion given the widespread cloud cover expected and difficulty
destabilizing.
Significant differences in model handling of the blocky pattern and
particularly the second low pressure system leads to lower
confidence and thus lower PoPs later in the forecast period.
Temperatures will moderate a bit mid to late week as the mid to
upper level cold pool associated with the first low departs, though
as with precipitation chances, uncertainty is higher in this regard,
as some guidance shows a connection to a longwave trough developing
with the second low, which could allow another intrusion of cooler
air into the region.
Nonetheless, the story of the next week or so will be temperatures
near to below normal and frequently damp and dreary conditions.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 145 PM EDT Sat May 3 2025
Impacts:
- Scattered showers at times in Western Indiana, overspreading much
of the region tonight
- In general, MVFR ceilings return south to north this evening and
into the overnight
- Some wind gusts near 15-20kt possible
Discussion:
A cut off low will meander around the Ohio Valley over the next
several days keeping stratus and showers around through the weekend.
Cigs have been largely VFR today, but will gradually lower to MVFR
levels this evening and into the overnight hours. Satellite and
radar show the most widespread areas of showers over Western Indiana
around KHUF. This area of showers should expect over South Central
Indiana through the evening then push northward overnight. Potential
for periods of IFR cigs and deteriorating visibility overnight as
showers become more widespread and low levels saturate.
Winds will mainly be out of the NE this evening becoming more
northerly tomorrow around 10-15 kts. Isolated gusts to 15-20 kts
possible at times.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...CM
SHORT TERM...50
LONG TERM...Nield
AVIATION...CM
Source:
IND issues Area Forecast Discussion (AFD) at May 3, 1:45 PM EDT---------------
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