Area forecast discussion
National Weather Service Lincoln Illinois
1153 PM CDT Monday Jun 17 2013
Discussion...
issued 902 PM CDT Monday Jun 17 2013
Current forecast looks OK but may need to tweak the isolated
thunderstorms in the north and extended it a few more hours...until
midnight. Then isolated showers/thunderstorms will be across the
central and southeast after midnight. Remainder of the forecast
looks fine with temperatures falling into the lower to middle 60s by
morning...with light winds and mostly clear skies. So will be
making some minor adjustments to the forecast. Update will be out
shortly.
Auten
&&
Aviation...
issued 1153 PM CDT Monday Jun 17 2013
Scattered high cirrus will slowly move across and out of the area
overnight at all sites. Then expecting light fog to
redevelop...but not as bad as last night and not as soon. So light
fog will be in MVFR category toward morning and likely dissipate
quickly after sunrise. Then expecting some scattered cumulus during the
morning hours ahead of the next system coming down from the
northwest. Models suggest a possibility of scattered thunderstorms
across parts of central Illinois during the afternoon
hours...mainly along the I-74 corridor. So will have thunderstorms in the vicinity at
pia...bmi...cmi for the afternoon. Have decided to include spi and
Dec as well given they will be close to the boundary as well and
outflow boundaries from existing storms could produce additional
storms to the west of the boundary. Then around sunset expecting
precipitation to end and also push to the east and southeast. Skies should
become scattered again for the evening. Do not southeast fog potential
tomorrow night as drier air should advect into the region. Winds
will be light and variable overnight and then become northerly
along the front and tomorrow evening.
Auten
&&
Previous discussion...
issued 220 PM CDT Monday Jun 17 2013
Short term...tonight through Thursday night
Main concerns this period will be with coverage of precipitation across our
southern counties tonight...associated with an mesoscale convective vortex over Missouri...
and with a weak surface boundary forecast to edge into our area
Tuesday afternoon. After that...somewhat cooler and less humid weather
will follow into Thursday before heat builds northward into the region
for the end of the week and next weekend.
Water vapor loop showing the convective complex from last night
producing a distinct mesoscale convective vortex over parts of western MO with new convection
developing to its east into east central and southeast MO and trying to
develop a bit further north into southern Illinois. Looking north...
several low amplitude shortwaves tracking east-southeast across the northern
plains. Once such wave pushing across Wisconsin with a weak surface boundary
shifting south Down Lake Michigan...which short term models suggest
will push across extreme Southern Lake Michigan later this evening.
The air mass ahead of this feature not particularly conducive to
widespread convection developing ahead of it so other than some
slight chance (isolated wording) for this evening across the far
north...it still appears the better probabilities for evening
convection will be tied to the Missouri mesoscale convective vortex as it tracks east-southeast well
to our south.
The northern stream wave across North Dakota looks a bit more impressive
than what models were depicting at this time yesterday. Models continue
to bring this wave east-southeast into the lakes region Tuesday afternoon with
a weak cold front edging south into our area. Convergence along the
boundary is not very impressive at all but with the timing of the
boundary into our area during peak heating...it still warrants slight
chance (isolated coverage) for Tuesday afternoon. Somewhat cooler and
less humid air will filter south across the area in the wake of the
shortwave Tuesday night into Wednesday bringing quiet and pleasant
weather for the remainder of the short term period.
Long term...Friday through Monday
Longer range models...at least the GFS and UK...were much more
aggressive with the retrogression of the subtropical ridge across
the central u... the stronger 500 mb flow further north
away from our area. The 12z European model (ecmwf) not nearly as strong with the
upper ridge as it takes a series of shortwaves from the longwave
trough across the Pacific northwest and temporarily flattens the ridge axis
to our west...keeping the amplitude much flatter over the lower
48...which gives our area a better chance for seeing scattered
convection...especially across the north during the weekend. Looks
as if the GFS solution may be overdone...compared to what it was
showing the past several runs. So far this Spring...the shortwaves
ejecting east-northeast from the western U.S. Troughs and their associated
convection have been successful in keeping the amplitude of the
ridge across the central portion of the country flatter. Will tend
to side more with the European model (ecmwf) this period but it won't make much of
a difference in the extended portion of the forecast with hot
weather returning for the weekend and the higher rain chances across
the north.
Smith
&&
Ilx watches/warnings/advisories...
none.
&&
$$
