IND issues Area Forecast Discussion (AFD) at Mar 1, 10:52 PM EST050
FXUS63 KIND 020352
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1052 PM EST Sat Mar 1 2025
.KEY MESSAGES...
- Clear and Cold Tonight
- Potential for locally heavy rainfall and possible strong
thunderstorms Tuesday through Tuesday night
- Cold air intrusion late Wednesday and Wednesday night. Snow
showers will be possible
&&
.FORECAST UPDATE...
Issued at 933 PM EST Sat Mar 1 2025
Skies have cleared this evening as broad surface high pressure was
building in from the Missouri Valley. This has allow temperatures to
quickly drop through the 20s. By morning, the center of the high
will be near the Ohio River. Hi-Res models are showing even a very
dry boundary layer through the night. Weak surface pressure gradient
below a sharp inversion will mean very light to calm winds. That and
the clear skies and dew points in the single digits to lower teens
will allow for the coldest night in a week or so with overnight lows
pegged for the middle teens to the lower 20s.
&&
.SHORT TERM (This evening through Sunday)...
Issued at 203 PM EST Sat Mar 1 2025
Synopsis:
Surface analysis early afternoon shows deep low pressure over
Quebec. High pressure was found over MN and IA. This was resulting
in cool, northerly cyclonic flow across Central Indiana. GOES16
shows lake cloud steaming off of Lake Michigan, spreading southward
over Indiana along with some diurnal stratocu. Radar was showing
some flurries/virga across Central Indiana beneath the cloud deck.
Aloft water vapor imagery showed a sharp ridge in place over the
western United States and a deep trough in place over the eastern
Great Lakes and Appalachia. This was resulting cool northwest flow
aloft along with lee side subsidence across the upper midwest
resulting the strong surface high.
Tonight -
Clouds are expected to dissipate as heating is lost this evening and
due to the building surface high pressure system which will result
in a more northwest lower level flow. That northwest flow should
result in any lake clouds staying north of Central Indiana. Forecast
soundings and time heights show the arrival of a dry column with
subsidence as the surface high arrives. Thus will trend toward skies
becoming clear tonight. With the arrival of subsidence, drier air
aloft will result in dew points in the single digits tonight with
light to calm winds. With ongoing cold air advection aloft and an
ideal radiational cooling set-up, lows in the teens will be common.
Sunday -
Sunny day for Sunday Sunday. The strong surface high will still
be present across Central Indiana as ridging aloft slowly builds
across our region. The cold air advection will come to an end as
the core of the cold air drifts east and surface flow becomes more
westerly. Time height and forecast soundings again show a dry
column with unreachable convective temperatures. A stray cirrus
cloud may pass within the flow aloft, otherwise, expect sunny
skies. Given the warm air advection, highs in the upper 30s to
near 40 are expected.
&&
.LONG TERM (Sunday night through Saturday)...
Issued at 203 PM EST Sat Mar 1 2025
Long term focus will remain on a strong system that is expected to
move through the Ohio Valley and Great Lakes regions Tuesday and
Wednesday.
Upper level analysis showcases a rather active pattern in store for
the Central US with nearly 8 waves currently in the Northern
Hemispheric plots. The most amplified of these waves looks to arrive
Tuesday through Thursday attached with a strong subtropical jet.
Prior to the Tuesday system, a weak shortwave upstream of the
synoptic ridge push into the Midwest. However, modest confluence
aloft and WAA ahead of the Tuesday system will act to "fill" the
low, eventually causing it to dissipate prior to reaching the Ohio
Valley. This will likely lead to cloudy, but dry conditions Monday
into Tuesday, along with moderating temperatures.
The aforementioned subtropical jet will phase ahead of the upper
trough Monday, leading a large area of collocated upper level
diffluence and WAA. In return, this will allow for efficient
pressure depletion over the lower Plains. At this point ensemble
members are in high agreement with a 990 or lower low forming over
KS Monday night, but start to show variance in how the low pressure
system evolves throughout Tuesday and Wednesday. Generally, the
expectation is for the surface low to track NE between a coupled jet
and behind the warm nose. However, the pace at which the low becomes
occluded will factor into overall impacts for central Indiana. For
now, we're at a point where rain is guaranteed for central Indiana
at times Tuesday evening and Tuesday night, with windy conditions;
However, uncertainties reside in the amount of rainfall and if any
thunder or severe weather will occur.
Following low passage Wednesday, cold air will quickly wrap around
providing a brief period of winter-like air late Wednesday through
Wednesday night. Some ensemble members show moisture wrapping around
the low as well which could lead to scattered snow showers, but
confidence in accumulating snow is low. This will quickly moderate
back towards seasonal late week as additional waves push in from the
west. Ensemble spread on these additional waves are far too high for
any accuracy on specifics as of this issuance for central Indiana;
regardless precipitation will be possible.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 1052 PM EST Sat Mar 1 2025
Impacts:
- None
Discussion:
Broad surface high pressure will move in from the Missouri Valley
overnight today. Subsidence and a dry column per Hi-Res soundings
will translate to VFR flying conditions and light to calm winds
through the TAF period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...MK
SHORT TERM...Puma
LONG TERM...Updike
AVIATION...MK
Source:
IND issues Area Forecast Discussion (AFD) at Mar 1, 10:52 PM EST---------------
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