JKL issues Area Forecast Discussion (AFD) at Jun 13, 4:40 PM EDT435
FXUS63 KJKL 132040
AFDJKL
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
440 PM EDT Thu Jun 13 2024
.KEY MESSAGES...
- A weak cold front brings a low chance (10-30%) for a shower or
thunderstorms on Friday into Friday evening.
- Hot and uncomfortable weather builds through this weekend, with
highs in low to mid 90s and heat indices peaking out around 100
degrees in some locations each afternoon from Sunday through
Wednesday.
- Disorganized afternoon showers and thunderstorms will be
possible from Monday onward.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 440 PM EDT THU JUN 13 2024
Another classic mid-June day has unfolded across eastern Kentucky
today with thermometer readings ranging from the mid 80s in the
Coalfield valleys to the upper 60s atop Big Black Mountain 20z.
Dew points are moderate, generally lower to middle 60s at most
locations. Also, the cumulus field from earlier in the afternoon
is quickly fading as diurnal heating wanes. The latest 500H
analysis shows northwest mid-level flow from the Canadian Prairies
into the Ohio Valley with an embedded shortwave trough moving
over the Upper Great Lakes. At the surface, high pressure ridging
extends across the Southeast US from a high over the Western
Atlantic. Meanwhile, a cold front trails from low pressure over
western Quebec to near/over Sault Ste Marie and then south near
Chicago and then west southwest into Nebraska.
The models are in good agreement through the short-term, showing the
high pressure departing to our east tonight as the upper level
shortwave troughing scoots toward the Northeast US and drags the
cold front into the Lower Ohio Valley. Convection developing
ahead of this boundary over southeast Iowa/northern
Missouri/northern Illinois is expected trek east southeast
overnight and largely dissipate due to lack of instability as it
moves up the Ohio Valley early Friday morning. There is a small
chance (up to 20%) that locations north of I-64 could see a brief
sprinkle or shower with the remnants of this convection during the
morning hours, though a period of thicker cloud cover is more
likely. Otherwise, expect an extensive cumulus field to develop
again on during the day on Friday, with a few of the updrafts
evolving into showers or thunderstorms (10 to 30% chance) by
afternoon ahead of a subtle mid-level disturbance. Later Friday
night, the actual cold front sags into and through eastern
Kentucky; but with the upper level forcing largely remaining well
north of the forecast area, expect only small shower chances
(10-20%) to linger into the nighttime hours. Temperatures will run
above normal through the period with forecast highs in the mid to
upper 80s on Friday and lows in the mid 50s, coldest northern
valleys, to the mid 60s, warmest southern ridges, on both tonight
and Friday night. Valley fog is expected in the typically prone
locations tonight. Anticipate minimal fog coverage on Friday
night, especially at locations that remain dry, since weak dry air
advection will be ongoing.
.LONG TERM...(Saturday through Thursday)
Issued at 358 PM EDT THU JUN 13 2024
Models are in general agreement for our area during the weekend.
Surface high pressure will be passing east southeast over the Great
Lakes at the start of the period, with its influence extending
southwestward over KY to supply us with a relatively dry air mass by
summertime standards on Saturday. Aloft, a trough over the
northeast CONUS will be departing eastward while ridging over the
lower-mid Mississippi Valley develops eastward. As the surface high
departs, our low level flow will turn toward the south southwest to
carry in warmer and more humid air to finish the weekend. As upper
level ridging builds in, rising geopotential heights and warming
aloft will also allow for additional warming/air mass modification
of the lower levels. Forecast soundings don't look favorable for
precip through Sunday, lacking enough instability to overcome
warming temps aloft.
The GFS and ECMWF are now in agreement for the high center at the
heart of the upper level ridge to gradually shift from the vicinity
of the southern Appalachians on Monday to the lower Great Lakes and
upper Ohio Valley by Thursday. However, they still differ in its
strength, with the ECMWF being stronger. That being the case, the
ECMWF is better at suppressing deep convection, with most days being
dry. The GFS allows for convection to bubble up through the warm air
aloft with scattered thunderstorms each day. This also impacts
temperatures, with the extra clouds and precip in the GFS preventing
readings from being as hot as in the ECMWF. A model blend yields
mostly slight chance POPs each day, mainly during the afternoon and
early evening hours. A compromise of forecast soundings suggests
temperatures slightly below NBM levels, but still plenty hot.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 145 PM EDT THU JUN 13 2024
VFR flight conditions will prevail throughout the period, outside
of the river valleys where fog will be found after 04Z tonight. A
sparse to scattered cumulus field south of I-64 this afternoon
will dissipate this evening with the loss of daytime heating.
Additional high level clouds are anticipated to spread southeast
late tonight and Friday morning ahead of a weak cold front. Winds
will be light and variable at less than 5 kts into Friday.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...GEERTSON
LONG TERM...HAL
AVIATION...GEERTSON
Source:
JKL issues Area Forecast Discussion (AFD) at Jun 13, 4:40 PM EDT---------------
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