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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
320 PM CST Friday Nov 27 2015

issued at 315 PM CST Friday Nov 27 2015

The latest surface analysis was indicating the main NE-to-SW oriented
cold front slowly pushing eastward from across the eastern Great Lakes...
to south of stl...and then trailing into eastern Texas. To the west
of that feature was a large ridge of high pressure across much of
the plains and extending into the northern Great Lakes/south of James
Bay. The local area more under the influence of the ridge with
low level north to northeasterly flow and it/S undercutting effect
making for a large deep inversion/warm wedge aloft centered around
700 mb mb. 12z upper air analysis and the latest water vapor loop were
indicating a few weak vorts embedded in lingering southwesterlies
aloft... skirting out of northeastern Kansas and across northern MO
at this time. These features helping induce a bout of isentropic lift and
associated areas of precipitation currently moving out of northeastern
Kansas...MO and southern Iowa.


Short term...(this evening through saturday)
issued at 315 PM CST Friday Nov 27 2015

Tonight...will have to walk these areas of precipitation eastward across the
southern third to half of the dvn County Warning Area for the rest of the afternoon
and through a few hours after dark with the far east central and
southeastern County Warning Area the last to clear at about 8 to 9 PM CST. Forecast
soundings and projecting low level thermal profiles into the evening...
bulk of this precipitation should continue to fall as light rain and
sprinkles...but the inversion profile aloft may allow for some ice
pellets mixed in at times especially on the western portions of the
precipitation fields. Will leave out freezing rain mention for now...but it
may get close/surface temperatures cooling to lowering wet bulb zeros for
possible freezing rain in the far southwestern dvn County Warning Area especially
after dark. After this round of lift exits off to the east after middle
evening...most of the 12z run models now suggest either none lift
across the local forecast area from midnight through Sat morning...or it
occurs further to the south across MO away from the southern County Warning Area. Thus
will trend to a dry forecast after midnight even in the far south.
Although expect some thinning and raising ceilings along and north
of i80...overrunning clouds streaming in from the southwest will
keep much of the area cloudy overnight. Wide range of low temperatures across
the County Warning Area from NW-to-se...low 20s to low 30s by early Sat morning.

Saturday...will keep the County Warning Area mainly dry with ongoing overrunning
clouds across the south half or 2/3s of the forecast area for much of the
day. But a few models propagate in another round of subtle
isentropic-type lift which may be enough to generate some patchy
light precipitation mainly across the south half of the dvn County Warning Area again from
late Sat morning into the afternoon. Forecast soundings suggest that by
the time precipitation falls...if it would be mainly in the
form of light rain and sprinkles again. With the south being held
down by cloud cover and partly to mostly sunny skies to the north...
high temperatures tomorrow may be rather uniform in the middle to upper 30s/
around 40 cwa-wide. ..12..

Long term...(saturday night through next friday)
issued at 315 PM CST Friday Nov 27 2015

Typical early December weather with a mostly light rain event the
forecast issue.

Long term forecast confidence assessment...good or above average
with main issue the decreasing risk of any freezing or frozen
precipitation on Monday. Trends are in line with yesterday/S discussion
of warmer low level thermal fields as surface and upper low passes
to our northwest so region in the warm sector. Otherwise...normal tendency
of diurnal highs and lows with favorable conditions a few degrees
too low/high for Max/mins.

Overview...initialization and verification fair to good with once again
the hi-res European model (ecmwf) most consistent and also most accurate in verification.
Prefer a 75/25 blend of hi-res European model (ecmwf) to GFS for days 2 through 7. Main
issue again mostly low level moisture a bit overdone especially the
American models.

Saturday night through Sunday night...very minor changes. Low to very
low chance of light rain far south sections that later shifts may be
able to pull as surface high to suggest subsidence. Highs upper 30s
to lower 40s. Mins mostly 20s Saturday nightto lower 30s and about
3 to 4 degrees warmer for Sunday night.

Monday and Monday night...light area of rain and possibly some sleet
northwest sections as surface low moves north. Precipitation amounts
remain light mostly below a quarte inch. Highs upper 30s to lower 40s
with lows in the lower 30s.

Tuesday...breezy and cold with wraparound clouds and flurries which
are handled as low chance probability of precipitation with no significant accumulations suggested.
Highs mostly in the middle to upper 30s. Tuesday night...clearing late
which should tend to kepp mins more in the upper 20s to near 30f.

Wednesday through Friday...very low warming trend and mostly dry to
dry with highs mostly in the 30s Wednesday rising into the 40s on Friday.
Mins upper teens to middle 20s Thursday and upper 20s to lower 30s on Friday.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1142 am CST Friday Nov 27 2015

Will slowly raise the MVFR ceilings at most sites to low VFR by this
evening. Will keep all tafs dry except at brl...although some
patchy light rain or rain/snow mix may get in the vicinity of mli at
times this afternoon. North to northeast surface winds of 10-20 kts to
become more 7-11 kts overnight. At brl...expect more light rain or
rain/snow mix. Can not rule out some ice pellets at times at brl
especially toward sunset if precipitation is still moving across the area.
Later tonight...several of the new model runs keep most of the
dvn forecast area dry or just some patchy light rain or freezing rain
moving east along the Iowa/MO border into west central Illinois after
midnight into early Sat morning. For now will knock back the
freezing rain mention out of the brl taf and go with vicinity late
tonight. A low chance for some MVFR fog at brl and possibly mli
tonight after 09z Sat...will only put it in at brl with precipitation in
the vicinity. ..12..


Dvn watches/warnings/advisories...



short term...12
long term...Nichols

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