Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 211118

Area Forecast Discussion
National Weather Service Wilmington OH
618 AM EST Sat Jan 21 2017

Temperatures will remain well above normal today into Sunday as
warm southerly flow persists across the region. A developing upper
level low pressure system will move across the southeastern
United States Sunday into Monday, bringing an increasing chance of
rain to the area. This will also be accompanied by somewhat cooler
temperatures for the start of the work week.


We have seen some patchy dense fog develop this morning, mainly
in areas that were able to clear off for a period overnight. With
the combination of some occasional stratocumulus and some
additional high level cloudiness moving in overhead, the fog has
been somewhat transient so think this will help limit more
widespread dense fog development through daybreak.

Broad southwesterly flow will continue across the region through
this afternoon. This will lead to some continued weak isentropic
lift through the day. Moisture is fairly limited through much of
the day but does begin to increase a bit later this afternoon,
primarily across our southeast. Will try to keep the majority of
our FA dry today and just introduce some slight chance pops late
in the day across our far southeast.

Another mild day is in store for us with highs mainly in the low to
mid 60s.


Quite a bit of uncertainty arises in the forecast tonight into
Sunday as the models continue to struggle with exactly how to
handle the developing upper level low that will move from the
Southern Plains to the East Coast through the rest of the weekend.
There are then additional uncertainties with the timing and
placement of mid level energy rotating around the upper low.

The 00Z NAM seems to be somewhat of an outlier with an elongated
upper low extending up toward the southern Great Lakes by Sunday
night. Meanwhile the 00Z ECMWF and CMC are farther south than the
00Z GFS with the track of the upper low across the southeastern
United States through the day on Sunday. The ECMWF is pretty much
keeping our area dry through the day on Sunday while the
remaining models are spreading a pretty good slug of moisture up
across our area. This seems to be backed up by the NCAR ensemble
forecast with most of its members spreading precipitation up into
our area through the day on Sunday. Will therefore go ahead and
trend that way and have high chance to likely pops developing
across our area. Some instabilities will also spread up into our
area through the day on Sunday so will go ahead and allow for at
least a chance of thunder across our southern areas for mainly
Sunday afternoon. Temperatures on Sunday will again be mild with
highs in the upper 50s to around 60 degrees.

Additional uncertainties arise for Sunday night into Monday as
the upper low pivots up across the mid Atlantic States. All of
the models are in pretty good agreement that there will be a
pretty heavy swath of precipitation somewhere along the pivot
point with the general consensus that this will primarily be
southeast of our FA. That being said, a few of the GEFS members are
showing 1.5 to 2 inches of rain across parts of our southeast
Sunday night into Monday and the parallel run of the GFS is
actually cranking out over three inches of rain at PMH. Based on
all of the timing and placement issues, there is quite of bit of
uncertainty here, but will go ahead and include a mention of some
heavy rain in our HWO product for our southeast.


Cooler conditions will continue into Tuesday as clouds remain in
place, with low-level winds beginning to shift to the west, and
eventually the southwest. A narrow ridge will move east through
the area on Tuesday night into Wednesday, shifting the pattern
firmly to warm advection for a relatively short period of time. It
is at this point in the forecast that confidence in specifics
becomes poorer, with increasing spread between the timing and
magnitude of features between GEFS members and between the 12Z GFS
/ 12Z ECMWF. However, there is high confidence in the general
pattern, with a surface low and upper trough moving through the
Great Lakes. This will allow a cold front to move east through the
Ohio Valley at some point on Wednesday, though limited moisture
will limit the chances for precipitation. Ahead of the front, the
pressure gradient will increase, and some slightly gusty
conditions may occur -- along with temperatures well above normal.
Max temps were increased for Wednesday, slightly above the model
consensus. Behind the front, cooler conditions through the end of
the week. There is a very large amount of spread in the timing of
additional precipitation chances on Thursday and Friday, as a
general pattern of broad troughing moves over the Great Lakes and
Ohio Valley through the end of the week. Temperatures during the
low end of the diurnal cycle may be cool enough to support some
snow, depending on when precipitation occurs.


Most TAF sites VFR this morning besides KLUK. There was some
initial fog/ visibility restrictions this morning but widespread
mid and upper level clouds has helped to bring the visibilities
back up. This afternoon an upper level low over Iowa will rotate
northeast keeping southerly winds across the TAF sites. At the
same time an upper level disturbance will eject northeast out of
Tennessee. Models have struggled on where exactly this upper level
disturbance will eject and therefore exactly where the
precipitation will setup. Latest set of model runs support the
upper level energy ejecting southeast of the terminals. High res
models also in general show precipitation remaining southeast of
the terminals. NAM forecasts soundings continue to advertise
instability this afternoon with the HRRR also showing
precipitation making it into the terminals. Taking a closer look
at the NAM forecast soundings shows not much moisture in the low
levels though. Overall, confidence has grown that the terminals
will likely remain precipitation free this afternoon and have kept
TAFs dry.

Saturday night into Sunday morning an upper level low across
Texas/ Oklahoma will push east allowing cigs to slowly lower
Sunday morning towards MVFR.

OUTLOOK...MVFR/IFR ceilings possible Sunday into Wednesday morning.




LONG TERM...Hatzos
AVIATION...Haines is the U.S. government's official web portal to all federal, state and local government web resources and services.