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000 
FXUS63 KJKL 211150 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
750 AM EDT Mon Oct 21 2019

.UPDATE...
Issued at 730 AM EDT MON OCT 21 2019

Hard to ascertain the extent of the fog given the high clouds now
in place blocking the satellite view and most of the automated
observation sites being situated on fog free ridgetops. Do 
expect it to be rather foggy in the river valley spots and the co-
op observers have been reporting dense fog with their obs this 
morning. The fog will likely clear our rather quickly over the
next hour or so as the winds start to kick up from the south 
soon. Have updated the grids to fine tune the extent of the fog 
and sky cover. Did also add in the latest T and Td obs/trends. 
These updates have been sent to the NDFD and web servers. 

&&

.SHORT TERM...(Today through Tuesday)
Issued at 430 AM EDT MON OCT 21 2019

07z sfc analysis shows high pressure just holding on over eastern
Kentucky keeping the winds light to calm and clearing the lower
clouds. However, a tighter pressure gradient is approaching from
the west associated with a deep surface low over the Plains and a
potent cold front well to our west. Some high clouds have been
drifting into eastern Kentucky through the latter part of the 
night and this is helping to clear the worst of the fog in the
Cumberland Valley, but additional pockets of dense fog remain to
the north and east where the lower clouds were slow to clear.
Meanwhile, temperatures vary from the lower 50s in some of the 
southeast valleys to around 60 degrees on the ridges in the 
northeast - dewpoints are similar to temperatures most places. 

The models have come into solid agreement with the main features
aloft that will affect the area in the short term portion of the 
forecast. The all now depict the core of a deep trough rolling 
east northeast through the Northern Plains and into the Upper 
Midwest today and tonight. This large trough will push a band of 
energy toward Kentucky by evening just ahead of its trough axis. 
This energy will combine with strong and veering winds aloft to 
present a severe threat for the region - extending into eastern 
Kentucky later this evening - though with far more uncertainty due
to quite limited instability - surface based and otherwise. 
Southwest mid level flow will be found for eastern Kentucky ahead 
of the main energy band. Look for the fast flow to become more 
zonal and northwesterly by the end of the period as the base of
the large trough moves on through. Given the overall model 
agreement have again favored the NBM solution along with details 
from the NAM12. 

Sensible weather will feature a foggy start to the day for many
locations, but this will mix out quickly thanks to increasing
southerly winds. These winds will pick up through the day ahead of
an approaching and potent cold front. Look for some gusts to near
35 mph at times this afternoon - mainly for western parts of the
forecast area. The winds will also support a pretty warm day with
upper 70s possible - while any showers hold off until closer to
dark. The convection will likely move into the area in the evening
as a pre-frontal trough-line of mainly showers, but a few
thunderstorms will be possible, as well. This band of showers will
be the main show with up to an inch of rain possible with its
passage along with even stronger wind gusts a concern - potentially
brought down from a 50kt low level jet passing overhead late this
evening. Will continue to highlight this threat in the HWO and 
social media postings. The front and its pcpn does eventually 
clear out of the area Tuesday morning with a much cooler day on 
tap accompanied by some still breezy winds from the west. 

Used the NBM as the starting point for all the short term grids,
though did make some adjustments to winds to increase them late
this afternoon and into the evening more toward the CONSRaw
values. As for PoPs and QPF, did tighten up the highest PoP
channel with the boundary moving through this evening and 
overnight, though also allowed for some lingering showers in its 
wake past 12z Tuesday. 

.LONG TERM...(Tuesday night through Sunday)
Issued at 410 AM EDT MON OCT 21 2019

Broad cyclonic flow will remain in place from the Intermountain West 
to the Atlantic Coast at midweek, with surface ridging centered near 
the lower Mississippi Valley and Gulf Coast nosing into southeast 
Kentucky by Wednesday morning. This will promote the potential for 
some areas of frost, particularly in the Cumberland Valley and west 
of Interstate 75, late Tuesday night into Wednesday morning. High 
pressure will reign supreme for midweek with high temperatures 
warming back toward the 70 degree mark by Thursday afternoon as 
return flow rounds the western fringes of the ridge. A few valley 
locales will stand the chance of some patchy frost once again 
Wednesday night into Thursday morning underneath clear skies, light 
winds, and with temperatures cooling into the mid 30s.

A trough will then dig across the Rockies and into the Great Plains 
out of the Canadian Prairies Thursday, establishing southwest flow 
locally and ushering in the above mentioned warmup. Still a good 
deal of uncertainty in the evolution of this system. A northern 
stream trough passing through eastern Kentucky Friday appears to be 
a good bet, helping to bring at least a minor cooldown for the first 
half of the weekend behind a cold front. However, the development of 
a southern stream low/trough remains the big kicker on how the 
details of our sensible weather will play out. If this latter 
feature does develop, Friday may well end up being dry with the 
southern system robbing the northern one of Gulf moisture. This 
southern stream energy would in all likelihood eventually ride up 
toward the Commonwealth, bringing a slug of moisture and beneficial 
rainfall to the Ohio Valley, including eastern Kentucky. Even if 
this feature does indeed form and bring us eventual rainfall this 
coming weekend, the timing will depend on the evolution and movement 
of the energy. The GFS and its ensemble mean remain the inconsistent 
solution and overall outlier in not developing a southern stream 
wave, but the latest run does suggest a little more digging on the 
southern fringes of the trough.

Renewed energy and troughing looks to again reload out west by late 
weekend into the final week in October as ridging holds in vicinity 
of the eastern Pacific. Thus given the overall progressive flow and 
periodic disturbances moving through, temperatures should hover 
relatively close to either side of normal through the weekend. This 
should also help to at least somewhat improve local drought 
conditions as rain chances continue in what is climatologically 
eastern Kentucky's driest month.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 750 AM EDT MON OCT 21 2019

The fog has now been relegated to the river valleys and no longer
threatens the TAF sites so have returned them to VFR. Light and 
variable winds will pick up speed over the next hour or so -  
becoming more southerly. Sustained speeds of 10 to 15 kts, with 
gusts of 20 to 30 kts, are expected during the afternoon. Clouds 
will be increasing and lowering through this evening, with showers
threatening out ahead of an approaching potent cold front. By 
late evening, expect showers and a potential for a few 
thunderstorms around so have included some VCTS for most sites, 
for a time, before reverting back to just some -shra after 
midnight. Cannot rule out some low level shear tonight, but 
expect the gusty sfc winds to mitigate the shear through the bulk 
of the upcoming night so have left LLWS out of the TAFs for now. 

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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