Area forecast discussion...updated
National Weather Service Jackson Kentucky
433 am EDT Wednesday may 22 2013
Short term...(today through thursday)
issued at 355 am EDT Wednesday may 22 2013
Early this morning...an upper level low had meandered to the upper
Midwest/upper MS valley region. To its south a rather significant
shortwave trough was working toward the middle and lower MS valley
regions. The upper level system will weaken to an open wave through
the period...with the lead shortwave trough to work into the area
this afternoon/evening and the main upper level system to reach the
central Great Lakes/lower to middle Ohio Valley and Tennessee Valley region by
the end of the period. At the same time...the associated surface low
should track well into the St Lawrence Valley through the end of the
period with the trialing cold front entering the commonwealth
today...though it should not cross eastern Kentucky until Thursday afternoon.
The region is currently in a lull in convective activity.
However...an outflow boundary from convection that occurred over
western Kentucky and in the MS River Valley on Tuesday evening has worked into
the County Warning Area. It is likely rather ill defined at this time...but still may be
enough to be a focus for convective development today. Also...debris
clouds or perhaps some scattered convection may be ongoing early in
the day as remaining convection over western and middle Tennessee works
northeast toward central and eastern Kentucky. However...breaks in the
clouds and some limited heating should allow temperatures to rather quickly
reach the 80s by midday to afternoon on Wednesday. This should lead
to moderate instability at about the same time that winds aloft will
also be increasing with low level jet core remaining generally to our
west and north. With the cold front working into the commonwealth
and a shortwave trough approaching from the southwest...a line or
several line segments of convection should develop to our west or
perhaps over the region this afternoon and work across the area into
the evening. The forecast wind profile is rather unidirectional and
middle level dry air is limited and considering few hail reports from
Tuesday afternoon...it would seem that damaging wind gusts would be the
main threat from storms this afternoon through early evening. Shear
will be a bit better generally along/north of the I 64 corridor and
an isolated tornado cannot be ruled out. In the severe weather potential statement...the slight risk
and damaging wind threat will be highlighted.
Deeper moisture will gradually be departing to the east tonight...but
at the same time...the main upper level trough and lead shortwave
will still be crossing the area. Convection cannot be ruled out well
into the night...especially in the east...but coverage of thunder
should become more isolated as the night wears on and with loss of
daytime heating intensity should wane by 3z...or 11 PM EDT...if not
earlier.
Daytime heating on Thursday combined with the cold front working across
eastern Kentucky and the upper level shortwave trough axis to work through
should generally coincide with daytime heating so high chance to
likely probability of precipitation were used for showers though enough instability will
linger for a few thunderstorms as well.
Long term...(thursday night through tuesday)
issued at 433 am EDT Wednesday may 22 2013
The models continue to agree with the long wave blocky pattern that
will dominate the Continental U.S. Through early next week.
A deep upper trough will swing through the Ohio Valley and eventually
reach the eastern Seaboard by Friday. Rain showers will gradually
wind down Thursday night across eastern Kentucky. Much cooler and
drier air will settle in through the first half of the weekend as a
large ridge of high pressure noses in from Canada. Highs on Friday
will be in the middle 60s...with lows Friday night down into the lower
to middle 40s.
The next feature of interest will be an inverted surface trough that
will move in from the northwest late this weekend into early next
week. The latest 00z European model (ecmwf) has backed off on the early arrival of
this feature compared to previous runs...however it still keeps this
boundary positioned much further south and more across our area than
the GFS...which keeps the boundary more along the Ohio River. As
such...will continue to compromise with a blend for now...bringing in
slight chance probability of precipitation late Sunday night and then chance probability of precipitation Monday
through Tuesday. Temperatures will recover to slightly above normal
by early next week...with highs topping out at around 80 by Tuesday.
&&
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 155 am EDT Wednesday may 22 2013
A relative lull in convective activity should occur over the first 6
to 10 hours of the period. Some isolated to scattered rain showers and
perhaps an isolated thunderstorms and rain cannot be ruled out over the next few hours
as an outflow boundary works in...but instability is rather minimal
at this time. And/after about 15z...convection should continue to develop and
strengthen and severe threat and strong wind gusts could impact all
three taf sites at some point during the 18z and 0z period. Outside of
any convection...valley fog will continue to develop and become dense
in river valleys...before dissipating by 13z. At the taf sites...some
MVFR in br is possible through 12z or 13z.
&&
Jkl watches/warnings/advisories...
none.
&&
$$
Short term...jp
long term...geogerian
aviation...jp
