Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Paducah Kentucky
537 am CST Friday Feb 27 2015

Update...
issued at 537 am CST Friday Feb 27 2015

The aviation section has been updated for the 12z taf issuance.

&&

Short term...(today through Sunday night)
issued at 400 am CST Friday Feb 27 2015

Still have patchy low clouds with flurries mainly across southern
Illinois and portions of west Kentucky. Will continue with
scattered flurries in the forecast through 12z...and re-evaluate
at that time whether to continue past daybreak.

Temperatures are not falling as much as expected...and wind
chills are struggling to drop below zero. Kmdh at -2 is the only
sub-zero reading as of 09z. Figure that 0 to -5 will catch most
areas by morning...so will continue with a mention in the severe weather potential statement.

The Arctic surface high is still expected to settle just north of
the area this afternoon. This will keep the area in northeasterly
flow at the surface...and as middle and high clouds increase
today...another cold day is in store for the region. At least with
the persistent northeast winds and mostly cloudy
skies...temperatures are not likely to drop much tonight.

Tried to model the forecast for the weekend after the European model (ecmwf) and
NAM. Looking for precipitation to spread eastward along the I-64
corridor Saturday night...and then spread south and east over the
entire region Sunday. It will start out as a bit of light snow
and then transition to freezing rain overnight. Tried to stay
close to wpc quantitative precipitation forecast through the event...and that results in only very
minor ice/snow accumulations in areas along and north of a line
from Marble Hill Missouri to Evansville Indiana.

Temperatures will be warming above freezing from southeast to
northwest overnight into Sunday morning. By 15z Sunday the entire
area is expected to be above freezing...as the precipitation
continues as all rain. Looking like a dreary day Sunday...but quantitative precipitation forecast
amounts are not staggering by any means. Looks like another brief
wintry episode with impacts dissipating quickly Sunday morning.
Will continue with a mention in the severe weather potential statement...but do not think it
worthy of even an Special Weather Statement at this time.

Long term...(monday through thursday)
issued at 400 am CST Friday Feb 27 2015

Exceptionally busy week coming up...with timing differences between
models and model runs making things challenging to say the least.

Precipitation will be ongoing Sunday night...as an incoming frontal
boundary passes through the area. The European model (ecmwf) continues to be faster
in bringing it through while the newest run and previous runs of the
GFS are a bit slower. Highest probability of precipitation will be during the evening with
decreasing probability of precipitation after midnight from northwest to southeast. Shallow
cold air pours back into the region behind this front. This will
mean a chance for the rain to change over to freezing rain/sleet as
the warm layer aloft remains in place.

Monday is looking drier and drier with each model run as high
pressure builds in. Have backed off probability of precipitation even more with this
package. If anything is left on Monday morning...it will be in the
far south and it could still be some freezing rain. Left Monday
afternoon dry.

Model continuity and agreement fades by the time you get to Monday
night. Models had been in decent agreement with a warm front lifting
back north across US...with moisture/quantitative precipitation forecast returning in earnest as
early as Monday evening. The European model (ecmwf) has really backed off almost
leaving US fairly dry the entire night. The GFS has backed off a
bit...advertising a mainly after midnight event. The Canadian model
is the most aggressive but believe the strength of the surface high will
likely prolong the return flow. Will split the Monday night weather grid
to show lower probability of precipitation during the evening and then ramping things up
after midnight. This ramp up in precipitation is highly supported by the
GFS precipitation mean and many of the ensemble members. The concern over
temperatures and hence precipitation type with this return moisture
does not look like as big a concern now...as everything suggests we
will be warm enough for a liquid event.

The main low pressure system to impact the area for Tuesday through
Wednesday will eject out of The Rockies and move east northeast
toward the Great Lakes. There continues to be timing issues between
models. However...the period of Tuesday through Wednesday does look
to be an active period with showers and thunderstorms commonplace.
The front associated with the system will move through either
Tuesday night or Wednesday morning. There will continue to be tweeks
every day to fine tune the timing of this system but there is high
confidence of a period of rainfall...some of it heavy at times which
will cause flooding concerns...in the Tuesday through Wednesday time
frame. In fact precipitable water values on Tuesday are above the
99th percentile for this time of year.

Wednesday continues to be challenging due to the timing
differences. The 00z European model (ecmwf) shows the actual front moving through
with heavy rain moving across the area. The 00z GFS indicates that
the front would already be through but a secondary impulse would
traverse the area in its wake and it would be cold enough for snow.
Lots of time to figure out what exactly will occur.

Temperatures will also be problematic. Temperatures in the 50s/60s look
likely sometime Tuesday into Wednesday morning before they crash
behind the front. These temperatures...along with dewpoints climbing
into the 50s and strong winds throughout the atmosphere could also
lead to possible severe weather sometime in the Tuesday through
Wednesday period. Stay tuned.

&&

Aviation...
issued at 537 am CST Friday Feb 27 2015

MVFR ceilings and some occasionally MVFR flurries have been
dancing around the area between the terminals overnight. Figure
that they will continue to miss the terminals until they dissipate
later this morning. Cannot completely rule out a brief MVFR
ceiling at all locations this morning. Otherwise the forecast is
VFR with high clouds overspreading the area and descending to the
5-10kft range by late tonight. Winds will veer to northeast as the
surface high settles just north of the region.

&&

Pah watches/warnings/advisories...
Illinois...none.
MO...none.
In...none.
Kentucky...none.
&&

$$

Update...drs
short term...drs
long term...CW
aviation...drs

National Weather Service Glossary of Abbreviations