Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 240544
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1244 AM EST Sat Feb 24 2018

...Updated Aviation Discussion...

.Forecast Update...
Issued at 525 PM EST Fri Feb 23 2018

A surface boundary has made itself known in the clearing area of
south-central Kentucky, where temps have climbed well into the 70s.
Satellite and webcams are showing a more convective look to the
clouds, and radar returns south of Bowling Green also looking more
convective. Hi-res model soundings over the area show some steep
lapse rates, so the whole body of evidence supports at least a
slight chance for thunder this evening, generally east of I-65 and
south of the Bluegrass Parkway.

&&

.Short Term...(This evening through Saturday night)
Issued at 150 PM EST Fri Feb 23 2018

...FLOOD WATCH FOR ALL OF SOUTHERN INDIANA AND MUCH OF CENTRAL
KENTUCKY THROUGH SATURDAY NIGHT...
...SIGNIFICANT FLASH FLOODING POSSIBLE SATURDAY NIGHT INTO SUNDAY
MORNING...
...STRONG TO SEVERE THUNDERSTORMS POSSIBLE SATURDAY EVENING THROUGH
SATURDAY NIGHT...

Stalled frontal boundary and southwest flow aloft is doing its job
of continuing to bring rains to the region. The morning sounding at
ILN had a precipitable water of 1.35", which is the second highest
value for the month of February, according to the SPC sounding
climatology. That ribbon of tropical moisture will meander across
the region, generally southward this afternoon into tonight, but
broaden over all of central KY and into southern IN by daybreak
Saturday. The moisture looks to pool further ahead of the cold front
forecast to move through the region Saturday night. This high
moisture content, combined with forcing along the front and
antecedent rainfall will set the stage for a significant flash flood
threat overnight. WPC has advertised a narrow band of high risk for
this threat given these conditions.

In addition to that significant threat, another threat will be
increasing winds ahead of that front by Saturday afternoon and
continuing into the night. Any stronger convective elements closer
to the front will have the chance to bring down 40+ mph winds.
Soaked grounds will make for weaker root systems on trees. A saving
grace here though is the lack of leaves on those trees, so they will
have less of a catch for those winds. Our region will be in the
right rear quadrant of a jet streak moving through the Midwest.
Combined with a low-level jet ahead of the front, we could see some
stronger winds mix down in the warm sector, and shear could allow
for some tornadoes to develop within the line.

.Long Term...(Sunday through Friday)
Issued at 150 PM EST Fri Feb 23 2018

Flow aloft becomes a little more zonal Sunday, cutting off some of
the Gulf of Mexico tap we`ve been under. High pressure moving into
the region will dry us out by late Sunday and into at least Tuesday.
Tuesday night, models continue in decent agreement with a warm front
lifting across the region. Unfortunately this front may stall
somewhere over the Ohio Valley as well before another cold front
blasts through the region some time Thursday. There still is some
timing difference on this setup, but it could exacerbate current
river issues.

Colder air looks to come in behind the front to close out the work
week. After a long stretch above normal, we should get down closer
to normal by Friday.

&&

.Aviation...(06Z TAF Issuance)
Issued at 1235 AM EST Sat Feb 24 2018

Early this morning, light rain showers will continue along with IFR-
LIFR conditions for BWG/LEX.  SDF looks to go IFR within the next
few hours with HNB going IFR closer to 10Z.  More steady rains will
arrive closer to sunrise as a warm front starts to lift north
through the region.  There could be an isld rumble of thunder with
convection after sunrise during the morning hours today.  However,
feel the better chance for storms will come this afternoon and
evening.  Sct-numerous showers and storms are expected this evening
into tonight as a cold front approaches the region.  Cigs should
improve as we head toward this evening with winds becoming gusty
from the SSW.

&&

.Hydrology...
Updated at 528 PM EST Fri Feb 23 2018

Copious amounts of rainfall have lead to excessive runoff and river
flooding in many locations over southern Indiana and central
Kentucky. The latest synoptic models indicate an additional 1-3"
inches of rain is likely through Sunday morning. This additional
rainfall will result in continued rises on area rivers, creeks and
streams. Continued river flooding is expected and will likely worsen
in coming days. A few river points have already achieved moderate
flood levels, and more are likely to follow. We could even see the
major flood category reached at Boston. For a complete list with
forecast hydrographs, please visit our website at:
https://water.weather.gov/ahps2/index.php?wfo=LMK

In addition to river flooding, typical low-land and flood prone
areas are likely to experience flooding at times through the coming
days. Widespread showers and storms forecast to move through the
area Saturday through Saturday night will pose an elevated flash
flood risk to much of the area. A Flood Watch is in effect through
Sunday morning.  Stay alert to current flood warnings at
www.weather.gov/lmk.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch through Sunday morning for INZ076>079-083-084-
     089>092.

KY...Flood Watch through Sunday morning for KYZ023>043-045>049-
     053>055-061>065-070>074.

&&

$$

Update...RAS
Short Term...RJS
Long Term...RJS
Aviation...AMS
Hydrology...AMS/BJS



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