Scientific Forecaster Discussion
fxus63 kjkl 260227 aab
Area forecast discussion...updated
National Weather Service Jackson Kentucky
1027 PM EDT Thu may 25 2017
issued at 1027 PM EDT Thursday may 25 2017
Went ahead and removed precipitation from the forecast for the
rest of the night. The last showers should be out of the area by
the top of the hour, and with no new development upstream, it
seemed reasonable to go ahead and axe precip for the rest of
tonight. The rest of the forecast was in good shape.
Update issued at 748 PM EDT Thursday may 25 2017
Updated the forecast to reflect precipitation exiting the much
quicker than the inherited forecast had been suggesting. The
latest nam12 and hrrr have eastern Kentucky precipitation free by
5 or 6z tonight. Based on current decrease in areal coverage of
precipitation seen in the latest radar imagery, decided it was
reasonable to get precip out of here earlier than previously
thought. The rest of the forecast should be in good shape as is.
Short term...(this evening through Friday night)
issued at 408 PM EDT Thursday may 25 2017
An upper level low pressure system continues to shift NE of Kentucky
this afternoon, pulling with it the surface low which is currently
located over north-central Ohio. Moisture from this system has
impacted much of eastern Kentucky today with widespread stratiform rain.
However, as the system continues to shift NE of the region, this
rain will continue to move east and taper off throughout the
afternoon/evening. With no instability to work with, continued with
no thunder in the forecast during this time.
Upper level ridging and surface high pressure will work in overnight
tonight, but llvl moisture may linger a bit in the form of low
clouds, eventually breaking up by daybreak Friday in many locations.
A warm front moving in to our north will likely keep cloud cover
in place across the NE County Warning Area. According to the latest soundings,
this llvl cloud cover should be enough to prevent fog in most
locations, though can't rule out some isolated valley occurrences.
During the day Friday, another surface low pressure system will be
located over the Southern Plains tracking NE into the mid
Mississippi Valley. This will send a warm front eastward into
Kentucky during the day Friday into Friday night, with the return of
southerly winds pulling moisture off of the Gulf of Mexico.
Temperatures will shoot up to near 80 by Friday afternoon, compared
to our 60 degrees today. Precipitation will also start moving in
along the Ohio River Friday night, before spreading into our region
during the day Friday. This could bring some pops into our northern
County Warning Area to round out the short term portion of the forecast. However,
after looking at the latest nam12 forecast soundings, all moisture
should be confined to a fairly shallow layer in the llvls, with a
very strong inversion located just above followed by dry air aloft.
In such a setting, there is nothing to support convection, so kept
with only rain mention in the grids during the overnight. Southerly
flow will also help keep overnight temps from bottoming out Friday
night/Saturday morning, only falling to the low to mid 60s.
Long term...(saturday through thursday)
issued at 447 PM EDT Thursday may 25 2017
The long wave pattern reveals amplifying flow once again into
next week. An upper level low will deepen across south central
Canada, with troughing taking shape across the Mississippi Valley
into early next week. A baroclinic zone will be laid out initially
along the Ohio Valley, with several short wave troughs traversing
the flow. This will bring continued storminess to eastern
Kentucky, with the possibility of severe weather as well as flash
flooding, given the already wet conditions in place. Will continue
to highlight these threats in the severe weather potential statement.
Cyclonic flow will linger into next week across the Great Lakes
and Ohio Valley regions, as the Canadian upper level low
gradually spirals its way east. The baroclinic zone will drop
south, yielding some return of drier weather; however, a few pops
may linger during peak heating in places between Tuesday and
Thursday, with the surface boundary still in the vicinity of the
For temperatures, slightly above normal readings will build back
into the region for this weekend as highs return to around the 80
degree mark. Humidity levels will also be on the rise. Once the
front exits to the south on Monday, generally near to slightly
below normal readings can be expected through the rest of the
period, with lower humidity levels.
Aviation...(for the 00z tafs through 00z Friday evening)
issued at 748 PM EDT Thursday may 25 2017
As an area of low pressure rotates of to our east this evening,
expect any lingering rain showers to come to an end at jkl, sym,
and sjs between 0 and 5z tonight. Ceilings and visible will remain
borderline IFR to MVFR up until this point. After the rain clears
out, ceilings will increase a bit, though may still remain MVFR
throughout the night. The latest forecast soundings are not
supporting much in the way of fog with the thick clouds in place.
Skies will slowly start to break up into the day tomorrow, with
generally scattered MVFR to low end VFR cigs. Winds will lessen to
generally less than 10 knots overnight, and then to less than 7
knots by during the day Friday.