498
FXUS63 KILX 161544
AFDILX
Area Forecast Discussion
National Weather Service Lincoln IL
1044 AM CDT Wed Oct 16 2013
.DISCUSSION...
ISSUED 1045 AM CDT Wed Oct 16 2013
Will be updating the forecast for cooler highs today (mid 50s IL
river valley and lower 60s southeast IL) and increase cloud cover,
similar to what we did yesterday. Otherwise rest of forecast looks
on track today with breezy west winds of 10 to 20 mph and gusts of
20 to 25 mph.
1002 mb low pressure was over the eastern end of upper mi penisula
with its cold front slicing through western Ohio and central KY and
west TN while a secondary frontal trof was over central WI into
southeast IA. Strong 550 dm 500 mb low was ne of Lake Superior
with a large upper level trof extending sw into IA/NE and southern CO
and northern NM where a short wave was. Low clouds over much of
central and nw IL as far southeast as Mattoon and also mid level
cloud deck southeast of I-70. Models show upper level trof
pivoting se toward central IL and moving into the state on Thursday
as short wave ejects from southern CO/northern NM toward the region.
This should keep more clouds over central and nw parts of CWA
while some sunshine over southeast IL allows for milder highs in
the lower 60s. Temps currently in the lower 50s with Bloomington
and Galesburg still at 49F.
07
&&
.AVIATION...
ISSUED 700 AM CDT Wed Oct 16 2013
The surface low is progressing farther to the NE into the Great
Lakes, while the cold front departs through Indiana. Wrap around
moisture in Minnesota and Iowa has already reached PIA and SPI,
and those MVFR clouds at 2-2.5K feet will reach all the way to DEC
and CMI by 13z. A couple of hours of IFR clouds between 700-900 ft
are being reported back across Iowa. Mixing and daytime heating
should help to lift those ceilings above 1000 ft by the time that
area reaches PIA around 16z. So no IFR conditions were included in
the 12z TAF issuance. Ceilings may climb above 3k ft to VFR levels
later this afternoon, but chances are that they will return to
MVFR in the evening.
We cant rule out some light drizzle or sprinkles today as a
surface trough reaches IL later today. We will monitor those
trends but keep a dry forecast for now.
Winds will increase from the west this morning, with sustained
speeds of 12-14kt and gusts to 22kt at times. Winds should
diminish below 10kt by evening
Shimon
&&
.PREV DISCUSSION...
ISSUED 243 AM CDT Wed Oct 16 2013
Latest surface map shows low pressure over the eastern part of the
Michigan Upper Peninsula. The cold front extends southwest, and
shows up as a narrow fine line through extreme southwest Indiana
per radar imagery from the Evansville radar. Narrow clear slot
just west of the Illinois River was about to be overtaken by a
large stratocumulus deck from the northwest, and excessive mid and
high clouds have been streaming northeast along the front across
most of the forecast area.
Main concern in the short term is with trying to time any cloud
breakup today, followed by rain chances late tonight and early
Thursday. Longer range issues focus on early weekend storm system
and the cool weather trend which will last much of the forecast
period.
SHORT TERM...Today through Thursday...
Latest RAP model guidance showing the mid/high clouds shifting
south toward the Ohio Valley later today, as the stratocumulus
pushes south of the I-72 corridor, although the NAM shows some
decent break up by late morning. Given the expansive nature of the
clouds, stretching all the way into northern Minnesota, will go
with the more pessimistic route and keep skies mostly cloudy
across the central and northern CWA today, with a bit of sunshine
over the south. Went a couple degrees below the MOS guidance for
highs, but this may need to be adjusted downward later if we are
unable to get any breaks to develop.
Shortwave currently near the 4 Corners region will zip eastward
later today. 00Z model guidance closes this off as it reaches the
Iowa/Illinois border toward sunrise Thursday, but ranges quite a
bit in terms of any precipitation over our area. NAM is nearly dry
with most of the precip near the remains of the earlier frontal
boundary south of the Ohio River, while the GFS has a narrow rain
axis just east of I-55. The ECMWF and Canadian models are much
more bullish with widespread showers. Currently leaning toward
more of the GFS solution but a bit more widespread with the
showers Thursday morning, fairly similar in coverage to the earlier
grids. However, am thinking that much of this will be out of the
area by early afternoon, although some slight chance PoP's will be
in the afternoon forecast across the east.
LONG TERM...Friday through Tuesday...
A deepening upper trough over the central U.S. will be the main
player this weekend, as a wedge of colder air drops southward from
Canada. Some potential exists for light rain Friday night or early
Saturday as the trough axis starts to shift eastward, but will
maintain 20% PoP's at this time. Some frost potential for Saturday
night as winds lighten and temperatures fall into the upper 30s
over the northern half of the CWA.
Going into early next week, periodic lobes of energy will drop
southward across the Midwest. The latest ECMWF remains quite
chilly similar to the past couple runs, with 850 mb temperatures
falling to around -5C by midweek, although the GFS is several
degrees warmer. For now, have not strayed too far from the
guidance, which keeps temperatures fairly similar throughout the
period.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$