Area forecast discussion
National Weather Service Jackson Kentucky
740 PM EDT sun may 19 2013
Update...
issued at 740 PM EDT sun may 19 2013
Things have quieted down for much of the area. However...very
unstable airmass continues to hold its ground along and north of
I-64...with many locations still around 80 degrees at the moment.
Updated earlier to include a mention of hail and winds as we have
seen some pretty good storms across central Kentucky and can't rule
out some strong storms across the northern portion of the area
over the next few hours. After sunset...stuff should really drop
off...with a quiet night anticipated. Still some question as to how
extensive the fog will be tonight. With dewpoints running well above
their readings from yesterday at this time...if we can clear out
tonight...the potential for dense fog would certainly increase. Will
continue to evaluate the need for any statements for advisories over
the next few hours to see how the clouds evolve or dissipate.
&&
Short term...(this evening through Monday night)
issued at 310 PM EDT sun may 19 2013
Middle/upper low over northeast Kentucky will continue to pull away with upper
ridging building into the area for Monday. An upper level local speed
maximum on the southern side of the low has helped support the
development of numerous showers and thunderstorms across the
southern part of the forecast area today. Speed maximum is forecast to weaken
and move away from the area. This combined with loss of daytime
heating should result in a quick decrease in convection this evening.
This is supported by the 12z NAM and latest hrrr. The hrrr does have
some convection lingering to at least midnight...and will keep a
slight chance of showers and thunderstorms in the southeast through
this time. Fog will develop again tonight...with locally dense fog
especially in areas where rain fell today.
With upper ridging over the area on Monday expect convection to be
less organized...even though low level lapse rates and surface based
instability will be greater than today. While there will not be any
upper forcing like today there will be numerous boundaries left from
todays convection...so will go with slight chance to chance
probabilities over all but the far western tier of counties for
Monday. Expect any convection on Monday to again quickly dissipate
during the evening.
With short range soil moisture and drought indices
showing wetter than normal conditions in the forecast area will
continue to disregard the GFS MOS high temperatures of 90 degrees for
Monday. Will go mostly with middle 80s. Record highs for Monday are
85 in 1987 at jkl and 88 in 1962 at loz. Will also lean towards the
NAM MOS probability of rain chance guidance which keeps low chances
for tonight and Monday night...with best chance for Monday. This is
the complete opposite of the GFS MOS guidance which places low
probabilities on Monday with the best chances tonight and Monday
night.
Long term...(tuesday through sunday)
issued at 310 PM EDT sun may 19 2013
The extended forecast begins with a ridge over the East Coast and a
series of middle level disturbances pressing east along the northern Continental U.S.
Border. A wave in the eastern plains has southerly flow at the surface
which will bring Gulf moisture into eastern Kentucky. Scattered to numerous
showers and a few thunderstorms will occur without much organization
as the surface low takes form and moves into the western Great Lakes. By Wednesday
the cold front will move into western Kentucky as the middle level opens into a
wave as it pushes over the eastern ridge. Wednesday night will see a series of
waves cycle around the southern edge of the 500 mb disturbance with
scattered areas of precipitation reflected at the surface. By early Friday morning
the upper pattern has changed to a plains ridge and coastal troughs.
Surface high pressure will drop from the northern plains and bring a period
of dry weather. That will last through the weekend as the surface high
drifts toward the East Coast with the upper pattern becoming more
progressive.
For sensible weather the southerly flow from the Gulf on Tuesday will
bring scattered precipitation along with temperatures into the middle 80s. This pattern
will continue through Wednesday with overnight lows restricted to the middle 60s
due to high dewpoints and clouds. Then on Thursday the first cold front will
cross eastern Kentucky with scattered storms and cooler temperatures as highs only
reach the upper 70s and lows Thursday night drop to around 60. With the
second surge of cold air following on Friday look for highs in the middle
70s and clearing late Friday will allow overnight lows to drop to the
middle 50s. The cool air will keep Sat highs in the lower 70s in spite
of a reduction in clouds early as the daytime mixing will help
increase cloud cover to complement the cooler north winds. As the
drier air moves into eastern Kentucky on sun the winds will diminish with the
high pressure crossing to our north and the sun will begin the
heating to push highs back into the middle 70s.
&&
Aviation...(for the 00z tafs through 00z Monday evening)
issued at 740 PM EDT sun may 19 2013
VFR conditions should hold at the taf sites through this evening.
Plenty of questions still abound about how much fog we will see
tonight. Models do not seem to have a good handle on the fog
potential tonight. If we can clear out...areas to widespread dense
fog could develop with dewpoints running fairly high at the moment.
For now...going to drop airports under minimums late tonight as a
combination of stratus or fog should get the job done. Adjustments
may need to be made at later times as we see how cloud cover evolves
over the next few hours.
&&
Jkl watches/warnings/advisories...
none.
&&
$$
Update...kas
short term...sbh
long term...dusty
aviation...kas
