Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLMK 192326
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
626 PM EST Mon Feb 19 2018

.Short Term...(This evening through Tuesday night)
Issued at 300 PM EST Mon Feb 19 2018

Partly to mostly cloudy skies were noted across the region this
afternoon.  Temperatures ranged from the lower to mid 70s across the
area.  The typical urban areas were a little warmer with KSDF
checking in with 77 thus far.  A bit more mid-high level cloud cover
will move through the region this afternoon.  So overall not
thinking we`ll see much more in the way of warming.  Highs should
top out in the 73-77 degree range for highs.  Partly to mostly
cloudy skies will be seen this evening and into the overnight hours.
Temperatures this evening will fall into the 60s before bottoming
out in the lower 60s by morning.

Tuesday looks to be a warm, dry, and breezy day across the region.
Deep southwest flow will be present with sustained winds of 15 to 20
MPH being commonplace.  Wind gusts up to 35 MPH are expected, though
a few gusts nearing 40 MPH at times is not out of the question.
Temperatures will be dependent on the amount of cloud cover we see
in the afternoon.  MOS guidance still hints at 80+ readings, but
feel that the low sun angle and the wet ground will temper that
quite a bit.  For now have gone with mid-upper 70s is most areas
with a few stations possibly tipping 80.  Temperature bust potential
is certainly there if we have more clouds in place.

Frontal boundary out to the west will make progress eastward
tomorrow night with clouds increasing.  Precipitation is expected to
move in from west to east with moderate to occasionally heavy
rainfall being seen at times.

.Long Term...(Wednesday through Monday)
Issued at 315 PM EST Mon Feb 19 2018

...SIGNIFICANT RAINFALL LIKELY FROM MID-WEEK AND INTO THE WEEKEND...

On the synoptic scale, the western US trough and eastern US ridge
pattern will stay in place throughout the extended forecast period.
The Ohio Valley will remain in between these features and within the
deep/moist southwesterly flow.  Several perturbations will move
through within the mean flow bringing several rounds of moderate to
occasionally heavy rainfall to the region.

The deterministic models continue to fluctuate with their axes of
heaviest rainfall.  The OP GFS keeps the bulk of its heavier
precipitation from southern MO into southern IN with widespread 5-8
inch amounts.  The OP Euro is a bit further south with its heaviest
QPF (5-8 inches) from NE TX into SW TN.  Both the GFS ensemble and
Euro ensembles are in pretty good agreement in keeping their axis of
heavy rainfall a bit more west of the operational models.  Both
ensembles paint a heavy QPF swath from NE TX into central IL.  As of
this writing, it appears that the OP models are outliers to the east
of the ensemble means. Within the ensemble there remains
considerable spread.  Just in an example, the GFS ensemble has a max
of 6.7 for Louisville through next Monday with a minimum of 3.0. The
average is around 4.75 inches.  Similar spreads were noted at
Lexington and Bowling Green.

For this cycle, we have attempted to infuse the latest data with the
previous forecast.  Utilizing the ensemble means here seems to have
worked well.  With several rounds of heavy rainfall expected, a
general 3-5 inches of rainfall will be see across the region.  The
heaviest rainfall looks to fall west of the I-65 corridor with
lesser amounts as one heads further east and southeast.  We will
need to be on guard for some stronger storms by late week.  The GFS
is most aggressive with this type of scenario.  So that bears
watching.  This rainfall on top of what has already fallen in the
last 7-14 days will lead to excessive runoff and we`ll see river
flooding in many of our basins by late this week.  Numerous flood
warnings are already out on the rivers, and more flood warnings are
likely later this week.

Temperatures through the period will remain mild for late February
standards.  Highs generally in the 50-60s will be seen on Wednesday
and Thursday.  With highs in the 60-70s likely by Friday and into
Saturday.  Overnight lows will remain mild with readings in the
upper 40s to the lower 50s.

&&

.Aviation...(00Z TAF Issuance)
Issued at 620 PM EST Mon Feb 19 2018

Mainly a wind and wind shear forecast as we are solidly in the warm
sector. The strong SW wind gusts will diminish after sunset, but
still expect gusts around 20 kt through the night. Low-level jetting
will crank the winds up to 40-50kt just 2000 feet off the deck,
so will mention LLWS after about 02-03Z. Will crank up the 30 kt
gusts again by mid to late morning, but SSW direction limits the
crosswind component, especially at SDF and LEX. Scattered cu will
fade with the loss of heating this evening, and re-develop in the
heat of Tuesday afternoon, but high enough to limit any operational
impact.

&&

.Hydrology...
Issued at 300 PM EST Mon Feb 19 2018

Minor flooding is in progress on the Ohio River at Tell City and at
Cannelton Lock and Dam.  McAlpine Upper is forecast to go into flood
later this evening and McAlpine lower will rise to above flood on
Tuesday.  Down on the Rolling Fork at Boston, KY, the river
continues to trend downward.  Boston is in action stage and is
forecast to drop below action stage Tuesday morning.  Down in the
Green River Basin, Woodbury and Rochester remain just below flood
stage.

The latest forecast suggest that a heavy rainfall event is likely to
occur from Wednesday and into the weekend.  Multiple rounds of
moderate to heavy rainfall are expected.  Widespread rainfall
amounts of 3-5 inches will be possible across southern Indiana and
central Kentucky.  Some locally higher amounts will be possible
depending on where the heavier axes of precipitation develop and
fall. This rainfall combined with already saturated soils will lead
to flooding problems in low-lying areas near rivers/creeks, and the
typical flood prone areas.  Sharp rises on area creeks and streams
are likely.

Ensemble river forecasts suggest that some of our rivers could rise
into the moderate flooding range by the end of the week.  Though
that is *highly dependent* on where the heavy rainfall occurs.
Operational models continue to differ considerably in their
placements.  The 12Z Euro is further south with it`s QPF while the
GFS is much further north.

Residents of southern Indiana and central Kentucky should remain
alert this week for flooding.  Stay tuned for the latest forecasts
and updates through the week.

&&

.Climate...
Issued at 620 PM EST Mon Feb 19 2018

Highs today broke the records for this date at Louisville, Bowling
Green, and Frankfort. Lexington has so far narrowly missed a
record. Tuesday`s forecast highs would smash the records for the
date, and threaten the records for the all-time warmest February
day.

        Tues 2/20       Feb All-Time
SDF     76 (2016)       81 (2/24/2017)
LEX     72 (2016*)      80 (2/23/1996)
BWG     76 (2017)       83 (2/28/1918)
FFT     73 (2016)       80 (2/24/2017 & 2/10/1932)

Record warm lows are expected on Tuesday. Here are the current
records:

SDF     55 (1994)
LEX     54 (1994)
BWG     55 (1994)

* and previous years

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Short Term...MJ
Long Term....MJ
Aviation...RAS
Hydrology....MJ
Climate......MJ/RAS



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.