Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 290628
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
228 AM EDT Wed Mar 29 2017

.UPDATE...
The SYNOPSIS...NEAR TERM and SHORT TERM Sections have been updated below.

&&

.SYNOPSIS...
Issued at 227 AM EDT Wed Mar 29 2017

Dry weather is expected today as high pressure over the Great
lakes will depart the region. Meanwhile a powerful low pressure
system over the southern plains will be pushing northeast toward
the Ohio Valley. This system will push into central Indiana late
Wednesday night and Thursday....bringing rain chances along with a
few isolated thunderstorms back to Indiana.

The upper low will remain over the area on Friday...ending the
work week on a wet note.

Dry weather is expected for much of the weekend as high pressure
builds in the wake of the departing low. More showers will return
to the area next work week as yet another low pressure system
arrives in the region.

&&

.NEAR TERM /Today/...

Issued at 227 AM EDT Wed Mar 29 2017

Surface analysis early this morning show High pressure in place
north of the Great Lakes continuing to influence Indiana`s weather
with dry but dirty northeast flow...with an inverted ridge axis in
place across Indiana. Deep and strong low pressure was found over
the southern plains.

Dry weather will continue to expected today as the HIgh to the
north in combination with strong ridging in place aloft provides
subsidence. forecast soundings and time heights show a mainly dry
column...expected for some trapped moisture in the lowest levels
due to an inversion. Time heights and forecast soundings suggest
a slow decrease in lower level RH through the day....thus a few
peeks of sun should work...although high cirrus from convection to
the west will also begin to invade as the upper ridge axis
departs to the east. Thus mostly to partly cloudy. With minimal
warm air advection and dirty NE flow continuing today...will trend
the forecast builder blends cooler by 1-2 degrees.

&&

.SHORT TERM /Tonight through Friday Night/...

Issued at 227 AM EDT Wed Mar 29 2017

Active and wet period expected to begin on late tonight through
Friday evening.

GFS/NAM continue to surge surge a warm front toward Indiana from
the southwest late tonight as the upper low approaches. Forecast
soundings show lower level saturation arriving late tonight. 300K
isentropic surface shows excellent lift and upglide arriving late
tonight and continuing into Thursday with specific humidities over
6 g/kg. Thus will trend pops higher than a forecast builder blend
at least on Thursday.

A second round of storms seem possible on Thursday afternoon as
forecast soundings suggest CAPE near 1000 j/kg by late thursday
afternoon and into the evening. Models suggest a second wave
pushing into the area as the upper low approaches from the
west...with this wave passing across Indiana mainly in the
evening. With rain expected during the morning and early
afternoon...uncertainty on how much instability will be present
is high as heating could be limited. None the less with major
forcing and moisture available with this powerful low...will
trend pops above a mavmos blend on Thursday night. Given the
dynamics possible...isolated severe weather will be possible.

GFS keeps the upper low passing across Indiana on Friday before
allowing the system to exit saturday night. Forecast soundings
continue to indicate a saturated column and good lift will be
expected with upper low in place. Again will trend toward pops
above a forecast builder blend.

By Friday Night the GFS and NAM suggest the system will be
departing and best forcing will be lost as weak high pressure
arrives in its wake. However...forecast soundings indicate trapped
lower level moisture on Friday night along with cyclonic lower
level flow still in place. Thus will keep any low pops suggested
by forecast builder for any stray shower or slowing progression
of this system.

&&

.LONG TERM /Friday night through Tuesday/...
Issued at 220 PM EDT Tue Mar 28 2017

The general weather pattern will continue through the long term. The
main focus will be on timing of showers.

Models and ensembles continue the pattern of having Pacific systems
move through the dessert southwest, Plains and then Ohio Valley with
ridging in between. One such system will be moving out of the area
Friday night. Ridging in its wake should allow for dry weather
through Sunday night. Then, the next system will be getting close
enough for pops by Monday. The system should then be on our doorstep
on Tuesday, so pops look good the rest of the long term. Instability
progs suggest some instability will be around if only weak. So, will
throw in isolated thunderstorms.

Look for below normal temperatures in the 50s on Friday but above
normal temperatures by Sunday as return flow sets up ahead of the
second system. Blend highs in the 60s look good.

&&

.AVIATION /Discussion for the 29/06Z TAFs/...
Issued at 1152 PM EDT Tue Mar 28 2017

MVFR ceilings will predominate during the first 8 to 12 hours of
the TAF period. Conditions will likely become VFR across all
sites tomorrow afternoon.

Moisture lingering under an inversion aloft will keep widespread
cloud cover in place overnight into Wednesday, with ceilings
likely to continue to build down overnight as cooling occurs. At
this time it appears likely that conditions will remain MVFR.

Winds through the period will generally be 10KT or less. Northerly
winds initially will gradually become easterly overnight into
tomorrow.

No significant obstructions to visibility are expected through the
period.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM...MK
AVIATION...NIELD


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