Scientific Forecaster Discussion
fxus63 klmk 230155
Area forecast discussion
National Weather Service Louisville Kentucky
955 PM EDT sun Sep 22 2019
issued at 945 PM EDT sun Sep 22 2019
A cold front advancing eastward from the Midwest will bring US some
rain chances starting in our northwest in a few hours and then into
the rest of the region Monday. A wide plume of moisture, which has
been bringing plenty of rainfall to points well west of here, will
narrow/become more focused as it enters our region and encounters
the dry air we've been experiencing. Still forcing along the front
as well as a low-level jet expected to strengthen overnight should
be enough to generate scattered to numerous showers along and north
of a Morgantown to Bardstown to Frankfort line by daybreak. Best
chances will reside over southern in. Forecast soundings show only a
narrow layer of instability aloft, and, given the upstream lack of
lightning will back off to slight chances of thunder over our
southern in counties overnight. Updated products going out now.
Short term...(this evening through monday)
updated at 305 PM EDT sun Sep 22 2019
Temperatures are peaking in the upper 80s and low 90s at this hour
as clear skies and gusty SW winds continue to contribute to well
above normal temperatures. Deep vertical mixing is allowing for some
dry air to combine with gusty winds (20-30 mph) and crispy small
fire fuels to produce an elevated wild and brush fire risk this
afternoon and early evening. Issued a Special Weather Statement to
cover this threat.
Otherwise, the main focus will be for shower and storm chances ahead
of an approaching cold front later tonight. Not much has changed
with the thinking regarding precipitation chances and timing. Best
chances will be around and after midnight across southern in and
into the pre-dawn hours across north central Kentucky. Will continue to
mention likelies across southern in, tapering to chance across
central Kentucky as the system enters our brief airmass in place, and
deeper moisture transport is lost as the low level jet weakens in response to
upper level support exiting our area to the NE. All of this will
result in lower chances across the Kentucky counties as we move through
late tonight into Monday morning. Also wanted to mention that
thunder chances really only appear to be over southern in later
tonight (and that may be a stretch) instability will really be
lacking or non-existent. Storm Prediction Center moved the general thunder line back
north of the Ohio River and like this move.
The cold front will pass through the area on Monday and can't rule
out some isolated to scattered development in our east and southeast ahead
of this feature through Monday. There are some hints that just
enough instability may develop ahead of the front to warrant an
isolated thunderstorm mention down there in the afternoon. Expect
highs to mostly be in the lower 80s tomorrow given the heavy cloud
cover and cooler advection behind the front.
Long term...(monday night through sunday)
updated at 250 PM EDT sun Sep 22 2019
Monday night - Wednesday...
As the cold front exits to the southeast Monday night, an area of
surface high pressure will build in over the region, allowing for
dry weather to again dominate through mid week. Temps will drop
slightly behind the front, moving a little closer to the
climatological normals. Lows Monday and Tuesday night will dip into
the 50s and highs Tuesday and Wednesday will remain in the low to
Wednesday evening - Thursday...
An upper level trough will swing across the northern plains and into
the upper Great Lakes on Wednesday, pushing another cold front
towards the region as the surface high slides off to the east.
Because the better forcing will remain to the north, expect precip
chances to diminish as the front approaches the region, with highest
pops in southern in and north-central Kentucky. Low temps Wednesday night
will remain in the lower 60s while highs Thursday will reach into
the lower 80s.
Friday - Sunday...
Our brief "cool down" will end on Friday as the synoptic pattern
becomes increasingly amplified and the southeastern Continental U.S. Ridge
builds back in for the remainder of the long term. Temperatures will
run about 10+ degrees above normal through the weekend, with highs
into the upper 80s/low 90s and lows into the upper 60s.
Aviation...(00z taf issuance)
updated at 735 PM EDT sun Sep 22 2019
Expect a steady southwest wind tonight as a cold front approaches
the region. Timing of this front will mean a weak band of showers
moving into the area Monday morning, with some chances for MVFR
conditions under those showers. A more persistent deck of clouds is
likely around the front during the morning hours, with a non-zero
potential for lowering to IFR. Winds will become west and
northwesterly behind the front, with skies clearing quickly in the