Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 190837
Area Forecast Discussion
National Weather Service Louisville KY
337 AM EST Thu Jan 19 2017
.Short Term (Now through Friday)...
Issued at 314 AM EST Thu Jan 19 2017
Moisture streaming northward east of a Plains upper low and on the
back side of an upper ridge moving from the Appalachians to the East
Coast will interact with small embedded disturbances, resulting in
another rainy period for much of the short term. The beginnings of
this can already be seen early this morning as showers are
developing over the middle and lower Mississippi Valley and heading
to the NNE. This activity will increase as the day goes on, with
showers gradually spreading across central Kentucky and southern
Indiana from southwest to northeast. Some weak elevated instability
may result in a few rumbles of thunder, especially over southern
Kentucky and west of Interstate 65.
Everyone should see rain tonight as an upper trof extending to the
southeast of the upper low moves overhead in concert with a surface
warm front. The rains will then exit to the northeast on Friday as
the upper trof swings into the eastern Great Lakes. Low clouds will
linger throughout the day, though, with some patchy drizzle or
sprinkles still possible after the main batch of rain moves away.
See the Hydrology section below for information on rainfall amounts
and flooding chances.
High temperatures today will be in the 50s. Temperatures tonight may
initially fall a couple of degrees in southern Indiana, but
otherwise will rise slowly as that warm front surges northward.
Friday will see highs in the 60s.
.Long Term (Friday Night through Wednesday)...
Issued at 332 AM EST Thu Jan 19 2017
We will sit in warm, moist flow on the east side of a large upper
trof over the western United States this weekend, with continued
shower chances the result. The trof will eject an upper low from the
Red River Valley Saturday night to the mid-Atlantic on Monday. The
most significant precipitation in the long term will be associated
with this feature Sunday afternoon and night as the upper low and
its surface counterpart cross Dixie. Though it`s January and we`ll
be on the north side of the system, the very mild air in place will
cause the precip to be all rain. As a matter of fact, some
thunderstorm activity will even be possible Saturday afternoon
through Sunday. Robust, possibly severe, convection over the Gulf
Coast States Saturday and Sunday may steal some of our available
moisture and instability, but widespread showers and embedded
thunderstorms still look like a very good bet, especially Sunday
afternoon and evening.
Temperatures will be much above normal with highs at least in the
60s each day. A high of 70 degrees isn`t entirely out of the
question on Saturday with strong, deep southwest flow. The record
highs for Saturday are 72 at Louisville and Lexington, 71 at Bowling
Scattered light rain will be possible on Monday as the southern
system begins to pull up the East Coast. We may be able to fit in a
dry Tuesday with some temporary weak upper ridging, but then the
western trof will begin a wholesale shift to the east and may
threaten us with more precipitation chances mid/late week.
Looking a bit beyond the 7 day forecast, long range outlooks are
still calling for a return to more typical wintertime temperatures
late next week, possibly dipping below normal as we finish January
and head into February. Some unsettled wintry weather may be in the
offing around the 27th-29th.
Issued at 311 AM EST Thu Jan 19 2017
For rainfall totals today through tomorrow, model blends and
WPC suggest amounts on the order of 0.75"-1.50" to be expected.
Maximum 6-hourly amounts around 0.50-0.75" will be possible,
especially late this afternoon into this evening over southern
Kentucky. These amounts are well below 6-hr FFG of 1.5-2.5" east
of I-65 and 2-3"west of I-65. Looking at NAEFS data for a few
particularly vulnerable spots shows ensemble median precipitation
amounts of 0.75" at Peaks Mill and Boston, and an inch at
Woodbury and Rochester. Most NAEFS members show no flooding at
Peaks Mill and Boston, and only minor flooding at Woodbury and
Rochester, mostly not until early next week given the lower Green
River`s typically slow response time. So, no Flood Watch will be
issued quite yet. *However*, the ground is very wet and heavy
downpours could still result in some local hydrological issues in
spots with poor drainage. This is especially true south and west
of a line from Hartford to Lebanon to Burkesville.
.Aviation (06Z TAF Update)...
Issued at 1215 AM EST Thu Jan 19 2017
Mainly scattered/overcast high clouds lie over central Kentucky
early this morning with high pressure centered across the region.
Some concern for light fog to form at BWG/SDF/LEX through sunrise as
T/Td spreads are already at 5F or less. Guidance hints at this
possibility but think the increasing high clouds overhead should
preclude any fog restrictions from developing.
Next weather system will bring increasing low/mid clouds and rain
showers to central Kentucky starting mid/late morning at BWG then
mid-afternoon at SDF and finally mid/late afternoon at LEX. Plan on
ceilings to drop into MVFR after precipitation onset, and then IFR
toward 00z and possibly LIFR to end the current TAF period.
Visibility restrictions are likely by afternoon and evening when
precipitation is expected to be the most widespread and heaviest.