Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 241639

Area Forecast Discussion
National Weather Service Indianapolis IN
1139 AM EST Sat Feb 24 2018

The AVIATION section has been updated below.


Issued at 300 AM EST Sat Feb 24 2018

A frontal system is expected to affect the area through tonight. In
the wake of this front, high pressure will move in for the early
parts of next week. Another frontal system may affect the area
around the middle of next week.


.NEAR TERM /Rest of Today/...
Issued at 926 AM EST Sat Feb 24 2018

Forecast is in good shape. Rain continues to fall across the
forecast area this morning, with the heaviest rain generally near
and south of Interstate 70. Radar shows more rain upstream, so
continued the high PoPs into early afternoon.

Short term models show a relative lull in the rain this afternoon
when the forecast area gets in between areas of forcing, so kept the
trend of lowering PoPs for a while this afternoon.

Warm front looks to remain south of the area today, so current
forecast high temperatures look good.

Previous discussion follows...

Radar indicates area of rain expanding across the area, ahead of a
mid level wave currently moving through Missouri. Short term model
guidance suggests this wave will move through the area later this
morning after sunrise, and pass off to the east during the early
afternoon hours.

Will continue with high PoPs through the midday hours today in
association with the passage of the wave. The heaviest rain looks
like it will occur after sunrise this morning, based on location
and timing of the best lift.

There may be a lull in the rainfall for a period later this
afternoon as this wave departs, as model guidance suggests the next
area of stronger lift won`t begin moving into the southwest zones
until close to sunset.

There is some concern for the axis of the heaviest rain shifting
north with time, as the 850mb front moves north. Will therefore
expand the Flood Watch a few counties farther north.

Low level thicknesses suggest the GFS MOS highs are probably a
little on the cool side. Will bump up the highs a few degrees.
Appears highs today probably won`t be reached until sunset.


.SHORT TERM /Tonight through Monday night/...
Issued at 300 AM EST Sat Feb 24 2018

Will continue with high PoPs tonight, as surface cold
front/occlusion moves through in the 250500Z-250900Z time frame.
Models suggest wind fields aloft will be quite strong, with a low
level jet in excess of 65 kts, and a mid level jet around 100 kts,
although lapse rates/instability continue to look rather poor.
Potential exists for high winds and embedded circulations with any
convection that develops near the front.

Rest of the short term looks dry, as high pressure builds across the
Ohio and Tennessee Valley.

Progged low level thicknesses suggest the GFS MOS temperature
guidance for the next couple of days looks reasonable, so only minor
adjustments planned.


.LONG TERM /Tuesday through Friday/...
Issued at 332 AM EST Sat Feb 24 2018

A somewhat zonal upper flow will occur across the U.S Tuesday and
Wednesday as a short wave over the central U.S. deepens into a
closed upper low over the southern Great lakes Thursday and southern
New England Friday.  The GFS and Canadian models are in pretty good
agreement on this scenario while the European indicates a less
phased scenario with a weaker northern stream disturbance and a
southern stream system.  Will lean more towards the GFS/Canadian
solution with a stronger more phased solution.

High pressure over the eastern U.S. Tuesday will move on to the east
as low pressure deepens over the plains Wednesday...moving into the
southern great lakes Thursday and to the southern New England coast
by Friday.  Tuesday will be dry and with low chance POPS late
Tuesday night and Wednesday.  Wednesday night and Thursday will be
wet as the low pressure area and a frontal system move through.
Then dry most areas by Friday.

Temperatures will be quite mild Tuesday through Thursday and a little
closer to normal by Friday. Went with highs in the upper 50s to
lower 60s Tuesday and Wednesday...55 to 60 Thursday and 40s to around
50 by Friday.   Lows will be in the 40s Tuesday and Wednesday night
and in the 30s Thursday night and upper 20s to near 30 by early


.AVIATION (Discussion for the 241800Z TAF Issuance)...
Issued at 1139 AM EST Sat Feb 24 2018

Poor flying conditions expected during the first half of the period,
then a gradual improvement to VFR by 12Z Sunday. Thunderstorms are
possible most sites mainly 01-07Z.

First surge of rain will be diminishing at valid time. Upstream
observations show IFR ceilings are common, so will go with IFR as
predominant all areas. However, there may be some breaks to as high
as VFR at times into mid afternoon.

Second surge of rain will move in from the southwest after 22Z or so
and then persist through the evening. IFR ceilings and some IFR
visibility will occur with this rain, along with embedded
thunderstorms. Low level wind shear will develop as a cold front
approaches later this evening.

The rain will move out overnight, and ceilings will gradually
improve as drier air works in. Winds will gust to over 25kt
overnight into Sunday morning.


Flood Watch through Sunday morning for INZ045>049-051>057-

Flood Watch through Sunday morning for INZ030-031-035>044.



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