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Area forecast discussion...updated 
National Weather Service Jackson Kentucky
828 PM EDT Monday Apr 27 2015

Update...
issued at 828 PM EDT Monday Apr 27 2015

Clouds continue to hang on as advertised early this evening across
the northeastern half of our area. Have made a few minor
adjustments to the forecast over the next few hours to capture the
latest satellite trends. Low temperatures look reasonable at this
time...although did try to slow the diurnal drop off somewhat
through late this evening...as the clouds are already hindering
the rate of cooling. Also added a touch of fog in the deeper river
valleys closer to dawn based on what had occurred this morning.

&&

Short term...(this evening through Tuesday night)
issued at 359 PM EDT Monday Apr 27 2015

A middle level shortwave is rotating into the appalachian region
around a middle level closed low centered near the northeastern US
coast. A middle level ridge is in place across parts of the upper MS
valley region. Meanwhile a closed low is rotating across the
Southern Plains. At the surface...high pressure is centered north of
the Great Lakes with ridging extending south and southeast into
the Ohio and Tennessee valleys.

Through the short term period...the shortwave will rotate by to
the east of the area this evening into the overnight...with middle
level heights rising as it departs. At the same time...the surface
high settle across the Great Lakes region. From Tuesday into
Tuesday night...the shortwave ridge will move across the Great
Lakes region to the Middle Atlantic States while the closed low over
the Southern Plains will rotate into the middle south. Corresponding
surface low pressure should strengthen across the Gulf Coast region
and track to the northeast Gulf of Mexico by the end of the
period. Also during this time...an upper level system will begin
to close off as it moves into the Great Lakes.

The disturbance rotating into the Appalachians may prolong the cumulus
until after sunset...pending how much the clouds that are now over
eastern Indiana and western Ohio hold together as they drop south
and southeast. However...skies should clear out during the evening
into the early overnight hours. Current dewpoints are generally in
the 30s across the region...with several areas in the lower 30s.
Assuming enough clearing...temperatures should again drop to near
levels of last night...perhaps a few degrees lower in a few
valleys that had higher dewpoints 24 hours ago. Due to the
uncertainty in the exact timing of the clearing and enough
pressure gradient to keep things stirred for a while after
dark...we opted to continue with the mention of patchy
frost...with this being mainly for the normally colder valleys or
typical cold spots.

Ridging should dominate into Tuesday evening...with temperatures
moderating further into the 60s in most places under mostly sunny
skies. Moisture will begin to increase late in the
period...particularly in the south. Showers could creep into
locations near the Tennessee border by the end of the period toward dawn
on Wednesday. However...higher chances for rain across that area
and all of the forecast area will hold off until the long term
period.

Long term...(wednesday through monday)
issued at 315 PM EDT Monday Apr 27 2015

The models appear to be in reasonably good agreement through the
extended with a split flow regime through the work week
transitioning into a more zonal pattern by the weekend. Within this
split flow regime...a closed low currently over northern Texas will
gradually shift eastward into the Tennessee Valley region. As the closed low
approaches the Tennessee Valley...a second low will dive down from Canada
and phase/merge with the closed low by middle week. This will result in
a strong low tracking from Kentucky slowly eastward off the coast during the
latter part of the week. As the low moves off the coast on
Friday...the upper level pattern transitions to zonal flow...with
higher heights building into Kentucky for the weekend.

At the surface...best chances for rain start middle week as the low
slowly pushes through the Tennessee Valley region eastward toward the coast.
During this time frame...eastern Kentucky remains along the western edge
of the precipitation...possibly into Friday....with our southeastern
counties having the best chances for rainfall. Temperatures during
this time will be on the chilly side...with highs about 10 degrees
below normal. However...as the low pushes off the coast...we will
see a warming and drying trend for the weekend. Models do produce
some light precipitation on Sunday but there is low confidence in the
forecast this far out in the extended. So have kept slight to
chance probability of precipitation for Sunday.

&&

Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 828 PM EDT Monday Apr 27 2015

Scattered to broken stratocu at 6-8k feet above ground level will continue to
be seen through 06z north of the hal Rogers Parkway and Highway 80
corridors...before dissipating through 12z. A bit of IFR or worse
fog will occur along some of the deeper river valleys between 08
and 12z as well. Otherwise...VFR conditions will prevail through
the period. Northwest to northeast winds of 5 to 10 kts...will
gradually diminish overnight and should generally remain at 5kts
or less for the remainder of the forecast.

&&

Jkl watches/warnings/advisories...
none.
&&

$$

Update...geogerian
short term...jp
long term...jvm
aviation...geogerian

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