IND issues Area Forecast Discussion (AFD) at Aug 12, 2:26 AM EDT612
FXUS63 KIND 120626
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
226 AM EDT Mon Aug 12 2024
.KEY MESSAGES...
- Partly Cloudy and Warmer Today; Sprinkles possible west.
- Mostly Cloudy and warmer Tonight.
- Daily storm chances arrive Thursday and continue into next weekend
&&
.SHORT TERM (Today and tonight)...
Issued at 226 AM EDT Mon Aug 12 2024
Synopsis -
Surface analysis early this morning shows a large and strong area of
high pressure centered over IL/IN and eastern KY. The high was
influencing the weather from the Dakotas to NY and PA and as far
south as Arkansas and Northern Mississippi. GOES16 shows Mostly
Clear skies across Central Indiana. Winds were light to calm and dew
points were in the comfortable middle 50s. Aloft water vapor showed
ridging in place over the western CONUS. This was leading to NW flow
aloft over the central Plains and the Ohio valley. A weak short wave
was found within this flow over IA and MO, producing some showers
and storms in the western parts of those states.
Today -
Models shows the northwest flow aloft will remain in place today as
the ridging over the western CONUS begins to build and push across
the Rockies. The previously mentioned short wave is expected to push
into IL and IN through the course of the day. Meanwhile, within the
lower levels the strong, broad and dry area of high pressure will
remain in place. This will result in dry lower levels through the
course of today. HRRR suggests precipitation development over IA and
MO early this morning, but as it encounters the dry air within the
lower levels in our area, the models suggest organized precipitation
will dissipate. Looking at the forecast soundings through the day,
the lower levels look to remain dry through the day, however the
upper levels show saturation as the short wave passes. Deep
saturation never arrives and pwats max out at only around 1.15
inches. Thus today we will expect more clouds in the area as the
short wave passes than we have seen as compared to the past few
days. Although measurable rain appears unlikely at this time, a few
sprinkles, mainly trace amounts, particularly across the west cannot
be ruled out.
There is some weak warm air advection expected today as the surface
high begins to shift eastward, allowing some warmer temperatures to
arrive from the southwest. Thus will trend highs about 1-2F above
persistence, mainly in the upper 70s and lower 80s.
Tonight -
Northwest flow aloft is expected to persist over Indiana as the
ridge axis arrives across the Plains states. The previously
mentioned short wave is expected to be departing through the evening
and overnight hours. Forecast soundings and time height sections
show mid level saturation persisting through the night. This is
indicative of passing high clouds. Looking at the lower levels the
strong area of high pressure will remain dominate, stretching from
the western Great Lakes, through Indiana to the deep south. Again
with mainly dry air in place within the lower levels along with
strong high pressure dry weather will be expected. But due to that
exiting short wave aloft, mid and high clouds will result in partly
to mostly cloudy skies overnight.
Again with slightly warmer air in place tonight along with the
expected cloud cover, overnight lows should be slightly warmer than
persistence, in the upper 50s and lower 60s.
&&
.LONG TERM (Tuesday through Sunday)...
Issued at 226 AM EDT Mon Aug 12 2024
Next week will feature a warming trend back to the 80s with daily
storm chances Thursday into next weekend. Troughing over the Great
Lakes region shifts east midweek with ridging building in on
Wednesday. A stronger trough develops in the Plains Thursday then
sits over the Great Lakes region Friday and into the weekend leading
to a wetter weather pattern locally.
Surface high pressure sits over the Great Lakes region Tuesday and
Wednesday keeping conditions fairly warm and dry for Central
Indiana. Expect highs in the low to mid 80s with mainly sunny skies.
Thursday onward, a stronger negatively tilted trough develops in the
Northern Plains with a surface low slowly tracking into the Great
Lakes Friday through Sunday, resulting in better moist air advection
over the Ohio Valley ahead of it and an increase in rain and storm
chances. Despite higher confidence in a pattern setting up that is
more favorable for daily storm chances across the region, there is
still quite a bit of model spread this far out on the speed and
track of the trough and associated surface low. So confidence
remains lower on the finer details. Confidence is increasing in
storms during the day on Thursday and into Thursday evening, so have
introduced "likely" wording for precipitation into the forecast with
"chance" wording Friday through Sunday. High temperatures during
this period will be highly dependent on coverage of storms and time
of day they arrive. Lowered Thursday's highs a few degrees to
account for increased clouds and storms during peak heating of the
day.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1206 AM EDT Mon Aug 12 2024
Impacts:
- Patchy fog possible at the outlying terminals around daybreak.
- Mainly VFR expected.
Discussion:
Surface high pressure was centered over IL/IN and E KY. This was
resulting in mostly clear skies and light to calm surface winds.
Quick northwest flow in place aloft was aloft streaming across the
region. This was allowing some mid and high level clouds to pass.
Another night of good radiational cooling is expected with mostly
clear skies and light to calm winds. Patchy fog is possible at all
but KIND in the predawn hours.
Any fog will dissipate quickly after sunrise with the high
persisting across the region. A quick moving short wave is expected
to pass through the afternoon. This will expand mid level clouds
into the area during the afternoon. Limited lower level moisture is
expected to prevent widespread, organized rain, but a few sprinkles
cannot be ruled to out. For now, threat appears low enough that no
mention is warranted at this time.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Puma
LONG TERM...CM
AVIATION...Puma
Source:
IND issues Area Forecast Discussion (AFD) at Aug 12, 2:26 AM EDT---------------
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