Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Jackson Kentucky
140 PM EDT Tuesday Mar 11 2014
issued at 130 PM EDT Tuesday Mar 11 2014
Did a quick update to fine tune sky cover and temperatures through
the next several hours...also put in the final forecast for high
temperatures today all based on the latest observation...trends...and consshort
guidance. These have been sent to the ndfd and web servers.
Have already decided to go ahead and issue a Wind Advisory for
tomorrow. The npw for this will be issued shortly.
Update issued at 1100 am EDT Tuesday Mar 11 2014
14z surface analysis shows high pressure through the southeast part of
the nation while a low pressure system is taking shape over the
Central Plains. A band of high clouds is seen on satellite over the
northern portion of the County Warning Area but this is starting to dissipate in the
last few frames. The stage is set for a very nice and warm day with
temperatures climbing into the low 70s in most locations thanks also
to south winds of 5 to 10 miles per hour. Currently...temperatures are in the
middle and upper 50s while dewpoints are in the upper 30s and lower 40s.
Have fine tuned maximum temperatures to remain on the high side of
guidance and massaged several point specific highs. Did also tweak
the T/dew point and sky grids per the current observation...trends...and guidance.
The grids have been sent to the ndfd and web servers with a zone forecast product one
to follow shortly.
Update issued at 802 am EDT Tuesday Mar 11 2014
Mainly freshened up the hourly temperatures...dew points...and sky
cover through this morning. Cirrus is a bit thicker across northern
Kentucky...however still expect this to thin out during the
day...yielding mostly sunny skies across most locations.
Short term...(today through Wednesday night)
issued at 358 am EDT Tuesday Mar 11 2014
The latest surface map features weak high pressure off of the
southeast coast...with Lee-side low pressure conglomerating across
the Front Range of The Rockies. Low level southwest flow in between
these two features continues across the lower Mississippi
Valley...allowing for above normal temperatures across eastern
Kentucky over the past days. Another Ridge/Valley split has ensued
during the overnight hours...with some of the cooler valleys dipping
into the middle 30s...while broader valleys and ridges range from the
middle 40s...to as warm as the middle 50s.
The models are in good agreement through the short term...as The
Rockies low emerges into the plains. Meanwhile...a deepening trough
will drop southeast out of Canada...which will intensify the surface
low rapidly as it heads east nearly along the Ohio River during the
day on Wednesday...before continuing to deepen and wrap Arctic air in
behind it as it reaches the New England coast by early Thursday
morning. This track is a tad further north than before...which will
keep the heavier quantitative precipitation forecast further north as well.
One more day of Spring weather will be on tap today...as highs top
out in the low to middle 70s. Clouds will then be on the increase late
today and especially tonight as the system nears from the west.
Showers will break out across the area towards dawn...with a few
thunderstorms possible as well. There may be a brief break in the
precipitation by mid-morning...before the cold front plows through
during the afternoon. Rain showers...with a few embedded
thunderstorms...along with strong southwest to northwest winds of 15 to
25 miles per hour...with gusts in the 35 to 45 miles per hour range will also occur. High
temperatures ranging from the low to middle 50s in the Bluegrass...to
the lower 60s across southeastern Kentucky...will be established in
the morning...as readings will plummet behind the cold
front...lowering into the 30s by late afternoon. Expect the rain
showers to turn to snow showers...some of which could limit the
visibilities significantly when combined with the wind. The very warm
ground will keep any minor accumulation restricted to elevated
Snow showers will continue into Wednesday night with the aid of
upslope. Temperatures will drop down into the teens...with winds
diminishing by late in the evening. Snow accumulations look to be a
half inch or less in the valleys...while the ridgetops may squeeze
out closer to an inch when all is said and done. For now...will
highlight the multiple impacts in a Special Weather Statement.
Long term...(thursday through monday)
issued at 358 am EDT Tuesday Mar 11 2014
Early in the period...a cold air mass will have moved into east
Kentucky...with 850 mb temperatures prognosticated to be near -15c on average at 12z on
Thursday. However...as the upper level trough departs that will be
responsible for the near term system...the 850 mb temperatures will also
moderate. Thursday will be rather cold by middle March standards. We stayed
very close to persistence for maximum T on Thursday as the met MOS
numbers...especially at jkl seemed too cold despite the anticipated
rather cloudy and cold start. Flurries will remain possible in Thursday
as long as the stratocu lingers as the low level flow will be
upslope. However...as drier air works in these should end in all
areas by midday.
Middle level ridging will build into the Ohio Valley region behind the
departing trough and should bring dry weather from midday Thursday into
Friday night. At the surface...high pressure building across the southeast
will lead to a rather cold night on Thursday night...especially in the
eastern valleys where some upper teens are anticipated.
Overall...the pattern and guidance suggest a Ridge/Valley split.
Temperatures should moderate rather quickly by Friday and opted to
go higher than the CR data grid Load. Recent MOS guidance is warmer
than the current forecast...so maximum T for Friday may need to be raised
further on later shifts.
Uncertainty increases from the weekend into early next week. A
shortwave trough should work across the Ohio Valley Friday night. This
system would produce increasing clouds at the very least per the
last couple of European model (ecmwf) runs...but the 0z and 18z GFS runs were more
moist Friday night into Saturday and generate some decent quantitative precipitation forecast. The
model blend had slight chance probability of precipitation for Friday night into Sat...and that
seemed reasonable given the inconsistency and model differences.
The weather later in the period will be largely determined by the
evolution of a couple of shortwaves to move from The Rockies and
into the plains over the weekend. In general...the models take an
initial shortwave into the Southern Plains...with some support for
closing this off. There is considerable model spread in where it
closes off and the track of any closed low early next week.
Meanwhile...a second shortwave is generally prognosticated to track across
the northern and Central Plains and reach the lower Ohio Valley late
sun or Sunday night. Models vary widely in how much moisture this
northern shortwave might have to work with as well as its timing.
The model consensus blend led to a long period of slight chance to
chance probability of precipitation with this from late Saturday night into Monday. Although
some of these periods could ultimately end up dry...the long period
of low probability of precipitation seemed in order at this time given the model and run to run
variability. Temperatures...especially high temperatures should average
below normal over the upcoming weekend into early next week.
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 140 PM EDT Tuesday Mar 11 2014
VFR conditions will hold through much of the night. Mainly high
clouds will be seen into the evening then ceilings will lower down
to MVFR between 06 and 12z...with showers threatening as well. Cannot
rule out a stray Bolt of lightning or thunder from these early
morning showers. The initial band of showers moves off to the east
east by middle morning Wednesday and just a slight chance for a shower
or thunderstorm will exist into the afternoon. South to southwest
winds of near 10 kts this afternoon will settle a bit tonight before
picking up dramatically on Wednesday. These will become quite strong
with southwest to west gusts to 30 or 35 kts possible by early
afternoon. Late tonight...winds will pick up just off the surface so have
added a low level wind shear remark for southwest winds to 40 kts through middle morning
at most sites.
Wind Advisory from 8 am to 10 PM EDT Wednesday for kyz044-