Area Forecast Discussion

FXUS63 KIND 211138 AFDIND

Area Forecast Discussion National Weather Service Indianapolis IN 738 AM EDT Wed Aug 21 2019

.UPDATE… The AVIATION Section has been updated below.

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.SYNOPSIS… Issued at 215 AM EDT Wed Aug 21 2019

Dry weather will be expected through early afternoon across Central Indiana as a cold front approaches the state from the west. The passing front and and associated upper level weather disturbance will bring chances for showers and storms to Indiana late this afternoon and tonight.

The front is expected to stall near the Ohio River on Thursday and Thursday evening. This may result in more chances for rain…mainly across southern Central Indiana.

High pressure is then expected to build across the Great Lakes on Thursday night and Friday…brining cooler and less humid air to the state on northeasterly winds. This will result in a dry and cooler start to the weekend.

Chances for rain are expected to return next work week.

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.NEAR TERM /Today/…

Issued at 215 AM EDT Wed Aug 21 2019

Surface analysis early this morning shows low pressure in place across Ontario. A cold front trailed the low across WI to IA and NB. High pressure was building across the Dakotas in the Wake of the front. GOES16 shows the leftovers of the convective system over the appalachians drifting eastward. Light SW surface flow remained in place across Central Indiana. Dew points remained rather high…in the middle 60s.

Forecast soundings and Time heights remain rather dry today. Aloft…NW flow looks to remain in place and the next short wave does not look to arrive until after at least 22Z. Forecast soundings show attainable convective temperatures…but a mid level inversion may inhibit deep growth. Thus will trend toward a partly cloudy sky for much of the day as best ingredients for precip only appear to arrive after 22Z. After 22Z will start to introduce pops in the western parts of the state. Given the expected sunshine…will trend highs at or above the NBM values.

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.SHORT TERM /Tonight through Friday Night/…

Issued at 215 AM EDT Wed Aug 21 2019

GFS and NAm booth suggest the arrival of a strong short wave on Tonight. Time heights show ample lift overnight with deep saturation overnight. Forecast so*ndings also show a deeply saturated column with pwats over 1.84 inches. Within the lower levers a cold front will be approaching from the NW. Thus we have some very favorable ingredients for precip in play. Will trend pops at or above the NBM tonight and trend lows warmer than the NBM given the expected rain.

On Thursday…broad cyclonic flow remains in place across Indiana aloft as an upper low is expected over Quebec. The GFS and NAM again suggest the passage of another short wave on Thursday. The NAm is a bit father south wit this feature than the GFS. Meanwhile at the surface…the stalled frontal boundary looks to be lingering near the Ohio river. Forecast soundings suggest attainable convective temperatures with minimal cap but much less CAPE. Thus will keep some pops in the forecast for Thursday…with highest pops across southern Indiana…trending towards lower amounts across the north.

A change in pattern is expected to build across the area on Thursday Night through Friday night. Sharp ridging aloft is expected to build across the upper midwest…resulting in NW flow and subsidence across the Great Lakes and Indiana. Strong surface High pressure is expected to build across the Great Lakes…resulting in cooler and drier NE surface winds for Indiana. Thus will trend toward a dry forecast here…with little change in temps from the NBM.

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.LONG TERM /Saturday through Tuesday Night/…

Issued at 359 AM EDT Wed Aug 21 2019

Below normal temperatures will prevaill Saturday and Sunday in the wake of a cold front. This front will eventually settle across the Southeast U.S., so any chances for showers and thunderstorms on Saturday will be confined to the southernmost counties. By Sunday, shower and thunderstorm chances will increase a bit as a mid level low advects more moisture into central Indiana. But, it won’t be until Monday and Tuesday when shower and thunderstorm chances really increase when that mid level low deepens and coincides with a warm front. Meanwhile, temperatures will also climb back to normal or slightly above normal with highs topping off in the mid 80s on Monday and Tuesday.

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.AVIATION /Discussion for the 21/12Z TAF Issuance/…

Issued at 723 AM EDT Wed Aug 21 2019

LIFR and lower will prevail through mid morning as fog continues to inhibit visibilities at TAF sites this morning. Conditions should improve to at least MVFR by late morning followed by VFR around early afternoon. After that though, there comes the threat for showers and thunderstorms once again. Will carry VCTS by late afternoon as a cold front approaches the state, bringing a threat for strong to severe thunderstorms once again. The best severe threat will be after Wed 20Z, but cannot rule out general thunderstorms throughout tonight with a trailing upper level disturbance. Meanwhile, winds will generally be light and variable outside of any convection.

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.IND WATCHES/WARNINGS/ADVISORIES…NONE.

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SYNOPSIS…Puma NEAR TERM…Puma SHORT TERM…Puma LONG TERM….TDUD AVIATION…TDUD