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000
FXUS63 KILX 241948
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
248 PM CDT TUE MAY 24 2016

.SHORT TERM...(Tonight)
ISSUED AT 240 PM CDT Tue May 24 2016

Mostly sunny, breezy, and warm conditions prevailed across central
Illinois this afternoon as the area remained under the influence of
surface/upper ridging.  A short-wave trough evident on water vapor
imagery over western Missouri will be the primary weather-maker over
the next 24 hours as it slowly tracks eastward.  Most models suggest
widely scattered thunderstorms will develop ahead of this feature
along the Mississippi River late this afternoon then will push into
west-central Illinois during the evening.  With plenty of dry air
evident at mid/low-levels, the environment will remain hostile to
widespread precip.  The HRRR has been consistently showing these
showers/storms dissipating toward midnight as they slowly track
toward the I-55 corridor.  Will therefore carry highest PoPs across
the Illinois River Valley tonight, with locations further east
around Champaign/Danville only seeing slight chance PoPs after
midnight.  Thanks to continued southerly flow and increasing surface
dewpoints, overnight low temperatures will remain in the lower to
middle 60s.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 240 PM CDT Tue May 24 2016

Southwest flow aloft will prevail across the Midwest through this
forecast period bringing very warm and humid weather to the region
with the difficult part of the forecast trying to pin down rain
chances ahead of rather weak low amplitude shortwaves that are
forecast to eject northeast from the main longwave trof over the
western U.S.  With the persistent southwest flow aloft, any frontal
boundary and main forcing mechanism is expected to remain well west
and northwest of our area through the week. The next shortwave over
the southern Rockies is expected to push across the central Plains
tonight and into the northern Plains on Wednesday bringing another
round of covection to our west. Just how far east these storms move
towards the mid-Mississippi River valley and away from the better
forcing remains to be seen with most of the deterministic models and
even a few of the CAM solutions not doing very well with the current
convection to our west and south.

With the aforementioned shortwave approaching on Wednesday, we
should see a weak boundary/warm front develop and shift north across
the area during the day, with most model solutions having this
feature to our north by late tomorrow afternoon where the better
forcing/low level convergence will be located. Overnight, it still
appears convection will fire on the nose of the 850 mb low level jet
and along and just north of the 850 boundary which suggests the
better threat for more organized storms will be closer to the 850
front which with this model run is to our north. Based on the 1000-
500 mb thickness difluence across our area, it appears the storms
may dive southeast into parts of our area early Thursday morning
where the better instability would be located. Still not worth much
more than 40 to 50 POPs at this point. Yet another shortwave will
approach the area from the southern Plains later Friday and into
Saturday possibly bringing another round of covnection to parts of
the Midwest.

Warm weather is expected to continue through the holiday weekend
with daily chances for showers and storms. The 12z GFS ensemble
and ECMWF solutions indicate a transition to an increase in 500
mb heights over the Midwest, with the stronger flow and thunderstorm
chances shifting into the northern Rockies east thru the upper Great
Lakes during the first week of June.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1245 PM CDT Tue May 24 2016

An upper-level disturbance currently over western Missouri will
track eastward, triggering widely scattered showers and
thunderstorms across west-central Illinois late this afternoon and
evening. Most models indicate that a few thunderstorms may impact
the western KILX terminals, with higher-res solutions such as the
HRRR focusing on the 00z-05z time frame. Still quite a bit of
uncertainty concerning convective development, particularly given
lack of strong forcing and dry mid/low-level airmass, so will only
mention VCTS at this time. Given likely diurnal nature of any
storms that develop, will keep KDEC/KCMI dry through the entire
18z TAF period. Ceilings if they occur will remain in the VFR
category. Winds will initially be from the south gusting to
between 15 and 20kt this afternoon, then will decrease to less
than 10kt tonight.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Barnes
LONG TERM...Smith
AVIATION...Barnes



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000
FXUS63 KLOT 241933
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
233 PM CDT TUE MAY 24 2016

.SHORT TERM...
233 PM CDT

Through Tonight...

Deep layer moisture in on the increase across the region with a
fetch of Gulf moisture riding on SSWLY flow.  Temperatures across
the region have risen into the middle to upper 80s with sfc
dewpoints in the middle to upper 50s over the western portions of
the CWA.  Dewpoints over NWRN Indiana remain a bit lower, in the
40s, but as upper level troughing slowly shifts EWD, the moist air
will overspread the entire area tonight.  Pcpn remains split to the
north, over Wisconsin and to the south, over eastern Missouri into
southern Illinois.  Have been battling with PoPs for the afternoon
and into the evening hours.  An area of showers have been developing
along a weak sfc trough/moisture axis in Wisconsin.  Some showers or
a few thunderstorms could sag south into the northern tier counties
south of the Wisconsin border, but expect that coverage would be
sparse.  In general, feel that much of the guidance has been
generating too much pcpn with this feature, so have tried to keep
PoPs in the low chance or slight chance range.  A pair of MCVs
moving through Missouri have been the focus of thunderstorms through
the day.  The short range guidance is in generally decent agreement
on continuing to indicate some convective development with these
features through the night. With the general SWLY flow upper ridging
building along the Mississippi Valley, there is a chance that some
thunderstorms may track into the southern portions of the CWA.  So
have increased PoPs over the southwestern portions of the CWA with
the area from LaSalle, to Pontiac to Gibson City having the greatest
chances for pcpn during the pre-dawn hours. With general increase in
moisture across the region, overnight lows will not be quiet as low
as in recent days.  Expect overnight lows tonight in the lower to
middle 60s.

Krein

&&

.LONG TERM...
329 AM CDT

Wednesday through Monday...

Southwest upper flow will prevail through this period keeping
temperatures above normal as well as multiple chances for storms.
Timing of these chances is fairly difficult...though it appears on
Wednesday that the afternoon and/or evening look to have the best
storm chances in nearly two weeks. The severe threat continues
low...greater than today/tonight...but still low. Have also
increased temperatures on Thursday which could see upper 80s to an
isolated 90 if sunshine prevails.

By Wednesday morning model solutions are in decent agreement of
the surface boundary being over southern WI or so...possibly lake
enhanced into far northeast IL. This is expected to lift northward
as a warm front with dew points in the mid 60s areawide...allowing
for MLCAPE values to peak around 1500 J/kg depending on just how
warm we reach /low to mid 80s expected/. The upper flow is
unsettled with a modest agreement in guidance of a low-amplitude
shortwave tracking over the area during the mid-afternoon to mid-
evening. This would be an ideal time for convective development if
it were to pan out. Shear values are much better further west of
the CWA and thus storm organization/intensity over our area may
struggle...but coverage still looks enough to warrant likely PoPs
in most of the CWA. Isolated severe storms with a brief wind/hail
threat could occur.

There appears to be a lull in much forcing during the day Thursday
with a capped environment likely temporarily be in place. Given
the nature of Wednesdays system...not expecting much for
lingering cloud cover...so Thursday could be quite mild. The 925mb
temperatures are forecast to be 20C to 23C. In the past 30 years
when 925mb temperatures have been this warm in northern Illinois
during late May...Chicago has had a mean high of 86 degrees. This
is why could see an isolated 90 or two for highs mainly in north
central IL if uncontaminated warming can occur.

Thursday evening and overnight the forcing for convection beings
to re-increase as the southern upper low of the western
trough...now over CA/NV...progresses into the Plains. A lot of
uncertainty on how far east forcing will be Thursday Night but
a few of the storms could be stout if they do form over the area.
Chances for rain continue through Friday and again may be higher
west depending on the track of the upper low and its forcing.
While chances for storms are in the forecast daily through the
Holiday weekend...it is a pattern that resembles a summer
one...i.e. it is not a pattern for widespread rain and refinement
in timing/details will improve as the week moves along.

MTF

&&

.AVIATION...
FOR THE 18Z TAFS...

Main forecast concerns for the period will be thunderstorm
potential/timing/coverage and visibility.

Activity from southern Wisconsin into northwestern Illinois
continues to try to develop. latest trends suggest that there is
limited convective potential with a split in coverage as the best
forcing is to the north of the terminals, over southern Wisconsin
and to the south, over eastern Missouri into central Illinois.
There is a chance that RFD could see some showers or thunderstorms
late this afternoon into early evening. latest guidance suggests
that the greatest potential for widespread pcpn over the region
will be by tomorrow afternoon. a strong mid level shortwave is
expected to track across the region while a warm front sets up
across northern Illinois into southern Lake Michigan. Combined
with a increase in deep layer moisture and continued warm
conditions...shra/tsra chances will increase through the day
tomorrow. Timing and coverage is still uncertain at this point, so
will only carry a prob03 for RFD for late tomorrow morning and
for ORD tomorrow afternoon.

SSWLY winds have increased into the 10-15kt range this afternoon
with occasional higher gusts. Wind speed will diminish in the
evening, with winds becoming more southerly overnight and
then southeasterly tomorrow morning morning as the warm front sets
up across the region.

Low level moisture will increase today and tonight with the
potential for mvfr vis/light fog. RFD/DPA/GYY could see visibility
drop to lower end MVFR or IFR. ORD/MDW will more likely remain in
MVFR ranges.

&&

.MARINE...

125 am...A weak cold front will slowly move southeast across
northern Lake Michigan late tonight. This front is expected to
become stationary across central portions of the lake by midday
Wednesday as low pressure begins moving north across the plains.
This front will then lift back north as a warm front Wednesday
night. As low level moisture increases across the region and
spreads over the cooler water...some fog is possible. A large
trough of low pressure is expected to persist over the plains
through early next week with prevailing southerly winds over the
lake. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

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000
FXUS63 KLOT 241814
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
114 PM CDT TUE MAY 24 2016

.SHORT TERM...
329 AM CDT

Through Tonight...

Today and tonight will feature a gradual transition to a more
unsettled and humid pattern while continued warm. Forecast
adjustments for the short term were to refine hourly timing of
chances of rain/thunder...confining that mainly west of I-55 for
today and this evening. These are mainly low chances...so
anticipating a majority of the CWA to remain dry through midnight.

The positively-titled upper trough across the western U.S. is
inching east with the upper ridging over the area to be nudged
eastward by tonight. The associated surface cold front has been
just as slow...draped from the eastern Dakotas to the western
Plains and will remain the primary focus for developing convection
today as is creeps southeastward. As is often the case with semi-
blocked patterns such as this and no presence of significant
forcing...convection has a difficult time advancing much further
east than its trigger areas. Early this morning...an area of
showers and some storms associated with an MCV in central IA is
moving east-northeast. This should continue to fade as it outruns
its forcing...though a 40-45 kt low-level jet as sampled on the
DVN VAD profiler probably will continue some showers into far
northwest IL after daybreak...with a lesser chance of reaching
north central IL.

A warm day is again on tap with 850mb temps again of 13C to 15C.
Surface winds will be more southwest today and steer in higher dew
points likely to reach the lower 60s by late today in north
central IL and elsewhere later this evening. This may make the
air mass slightly more difficult to warm and some clouds west of
I-55 will likely keep readings a few degrees shy of yesterdays.
Eastern areas should peak similar to yesterday with mid 80s.

While the front itself will remain well northwest of the CWA
today...gradually increasing convergence across eastern IA into
southern WI might be enough to spark late day/evening isolated
storms that could move into north central IL. Have maintained low
chances for that. While instability may peak in excess of 1000
J/KG...bulk shear remains low in the absence of any noteworthy
short wave...so the chance for anything severe is low.

Later tonight as a surface low strengthens in the western
Plains...warm and moist advection aloft will gradually increase.
It is possible some storms may develop in this regime...again
more favored across the western forecast area. It will be a mild
night with mid 60s forecast for lows...about 15 degrees above
normal.

MTF

&&

.LONG TERM...
329 AM CDT

Wednesday through Monday...

Southwest upper flow will prevail through this period keeping
temperatures above normal as well as multiple chances for storms.
Timing of these chances is fairly difficult...though it appears on
Wednesday that the afternoon and/or evening look to have the best
storm chances in nearly two weeks. The severe threat continues
low...greater than today/tonight...but still low. Have also
increased temperatures on Thursday which could see upper 80s to an
isolated 90 if sunshine prevails.

By Wednesday morning model solutions are in decent agreement of
the surface boundary being over southern WI or so...possibly lake
enhanced into far northeast IL. This is expected to lift northward
as a warm front with dew points in the mid 60s areawide...allowing
for MLCAPE values to peak around 1500 J/kg depending on just how
warm we reach /low to mid 80s expected/. The upper flow is
unsettled with a modest agreement in guidance of a low-amplitude
shortwave tracking over the area during the mid-afternoon to mid-
evening. This would be an ideal time for convective development if
it were to pan out. Shear values are much better further west of
the CWA and thus storm organization/intensity over our area may
struggle...but coverage still looks enough to warrant likely PoPs
in most of the CWA. Isolated severe storms with a brief wind/hail
threat could occur.

There appears to be a lull in much forcing during the day Thursday
with a capped environment likely temporarily be in place. Given
the nature of Wednesdays system...not expecting much for
lingering cloud cover...so Thursday could be quite mild. The 925mb
temperatures are forecast to be 20C to 23C. In the past 30 years
when 925mb temperatures have been this warm in northern Illinois
during late May...Chicago has had a mean high of 86 degrees. This
is why could see an isolated 90 or two for highs mainly in north
central IL if uncontaminated warming can occur.

Thursday evening and overnight the forcing for convection beings
to re-increase as the southern upper low of the western
trough...now over CA/NV...progresses into the Plains. A lot of
uncertainty on how far east forcing will be Thursday Night but
a few of the storms could be stout if they do form over the area.
Chances for rain continue through Friday and again may be higher
west depending on the track of the upper low and its forcing.
While chances for storms are in the forecast daily through the
Holiday weekend...it is a pattern that resembles a summer
one...i.e. it is not a pattern for widespread rain and refinement
in timing/details will improve as the week moves along.

MTF

&&

.AVIATION...
FOR THE 18Z TAFS...

Main forecast concerns for the period will be thunderstorm
potential/timing/coverage and visibility.

Activity from southern Wisconsin into northwestern Illinois
continues to try to develop. latest trends suggest that there is
limited convective potential with a split in coverage as the best
forcing is to the north of the terminals, over southern Wisconsin
and to the south, over eastern Missouri into central Illinois.
There is a chance that RFD could see some showers or thunderstorms
late this afternoon into early evening. latest guidance suggests
that the greatest potential for widespread pcpn over the region
will be by tomorrow afternoon. a strong mid level shortwave is
expected to track across the region while a warm front sets up
across northern Illinois into southern Lake Michigan. Combined
with a increase in deep layer moisture and continued warm
conditions...shra/tsra chances will increase through the day
tomorrow. Timing and coverage is still uncertain at this point, so
will only carry a prob03 for RFD for late tomorrow morning and
for ORD tomorrow afternoon.

SSWLY winds have increased into the 10-15kt range this afternoon
with occasional higher gusts. Wind speed will diminish in the
evening, with winds becoming more southerly overnight and
then southeasterly tomorrow morning morning as the warm front sets
up across the region.

Low level moisture will increase today and tonight with the
potential for mvfr vis/light fog. RFD/DPA/GYY could see visibility
drop to lower end MVFR or IFR. ORD/MDW will more likely remain in
MVFR ranges.

&&

.MARINE...

125 am...A weak cold front will slowly move southeast across
northern Lake Michigan late tonight. This front is expected to
become stationary across central portions of the lake by midday
Wednesday as low pressure begins moving north across the plains.
This front will then lift back north as a warm front Wednesday
night. As low level moisture increases across the region and
spreads over the cooler water...some fog is possible. A large
trough of low pressure is expected to persist over the plains
through early next week with prevailing southerly winds over the
lake. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO




000
FXUS63 KILX 241745
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1245 PM CDT TUE MAY 24 2016

.UPDATE...
Issued at 1052 AM CDT Tue May 24 2016

Morning surface analysis shows 1020mb high anchored over the
Southeast US...while frontal boundary remains stalled from the
Upper Midwest into the Plains. Aloft...southwesterly flow is
prevalent across the region...with one short-wave trough evident
over eastern Kansas. The Kansas wave is currently setting off
widespread showers and thunderstorms across central/western
Missouri...and this activity is slowly spreading eastward. Despite
the forward progress noted on radar imagery...the airmass across
central Illinois remains capped and quite dry as evidenced by the
12z KILX upper air sounding. Therefore any convection that forms
across Missouri will have difficulty moving into the more hostile
environment east of the Mississippi River. Most high-res models
keep the KILX CWA dry through at least early afternoon...with a
few showers/storms trying to work into the area later in the day.
Have updated PoPs to remove rain chances this morning, and have
limited slight chances this afternoon to locations along/southwest
of a Canton...to Taylorville...to Olney line. Have also made some
adjustments to hourly temps and afternoon highs...with readings
topping out in the lower to middle 80s.

&&

.SHORT TERM...(Today)
ISSUED AT 317 AM CDT Tue May 24 2016

For today, models are not depicting any coherent disturbance to
bring any substantial lift into central IL, as a shortwave over the
Dakotas and Iowa is expected to lift northeastward likely keeping
its influence out of our area, and another on over SE Missouri to
propagate eastward through southern IL, potentially grazing Clay and
Richland counties. Nevertheless, with increasing moisture resulting
in dewpoints reaching around 60 by afternoon...enough instability
will result with afternoon heating that isolated thunderstorms could
form along any leftover boundaries from convection in the region
overnight. Therefore, have trimmed thunderstorm chances to slight
category for today SW of a Bloomington-Effingham line. With several
hundred to 1500 J/KG CAPE progged west of the Illinois River, a
few of these could become strong with hail and gusty winds,
therefore SPC has outlooked these areas in a marginal risk for
severe thunderstorms.

Otherwise...highs today should reach the low 80s today, down
marginally since Monday due to increased cloud cover, and
southerly winds around 10 mph will continue through the day.

.LONG TERM...(Tonight through Monday)
ISSUED AT 317 AM CDT Tue May 24 2016

Upper level flow from the southwest expected to persist most of the
week, with the upper low currently just south of San Francisco
expected to only reach western Kansas by Friday evening in a weaker
state. Once that low lifts northeast into the northern Plains this
weekend, another will dig southward across the western U.S. and keep
the southwest flow continuing. Net result will be an extended period
of warm and somewhat humid conditions lasting into the holiday
weekend. Individual ripples in the upper pattern will enhance rain
chances periodically, as surface boundaries to our north will not
move much. While it will not be a continuous washout, such a pattern
makes it difficult to pin down any dry periods in the forecast.
Thus, most of the forecast periods will continue to have at least a
chance of showers and thunderstorms.

Currently looks like most of this evening will be dry over the
forecast area, with an uptick in rain chances after midnight as an
MCS organizes to our northwest. GFS tracks its remnants more or less
on top of us, while the ECMWF and NAM keep most of them to our
north. Another thunderstorm cluster more likely to affect the CWA
Wednesday night, and likely PoP`s were kept from about Havana-Paris
northward. Latest SPC outlooks have backed off on the severe weather
chances over our area the next few days, as while there will be
decent instability, shear parameters are rather week. However, with
precipitable water values rising to around 1.5 inches, some of the
storms will produce locally heavy rainfall.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1245 PM CDT Tue May 24 2016

An upper-level disturbance currently over western Missouri will
track eastward, triggering widely scattered showers and
thunderstorms across west-central Illinois late this afternoon and
evening. Most models indicate that a few thunderstorms may impact
the western KILX terminals, with higher-res solutions such as the
HRRR focusing on the 00z-05z time frame. Still quite a bit of
uncertainty concerning convective development, particularly given
lack of strong forcing and dry mid/low-level airmass, so will only
mention VCTS at this time. Given likely diurnal nature of any
storms that develop, will keep KDEC/KCMI dry through the entire
18z TAF period. Ceilings if they occur will remain in the VFR
category. Winds will initially be from the south gusting to
between 15 and 20kt this afternoon, then will decrease to less
than 10kt tonight.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...Barnes
SHORT TERM...Onton
LONG TERM...Geelhart
AVIATION...Barnes




000
FXUS63 KLOT 241132
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
632 AM CDT TUE MAY 24 2016

.SHORT TERM...
329 AM CDT

Through Tonight...

Today and tonight will feature a gradual transition to a more
unsettled and humid pattern while continued warm. Forecast
adjustments for the short term were to refine hourly timing of
chances of rain/thunder...confining that mainly west of I-55 for
today and this evening. These are mainly low chances...so
anticipating a majority of the CWA to remain dry through midnight.

The positively-titled upper trough across the western U.S. is
inching east with the upper ridging over the area to be nudged
eastward by tonight. The associated surface cold front has been
just as slow...draped from the eastern Dakotas to the western
Plains and will remain the primary focus for developing convection
today as is creeps southeastward. As is often the case with semi-
blocked patterns such as this and no presence of significant
forcing...convection has a difficult time advancing much further
east than its trigger areas. Early this morning...an area of
showers and some storms associated with an MCV in central IA is
moving east-northeast. This should continue to fade as it outruns
its forcing...though a 40-45 kt low-level jet as sampled on the
DVN VAD profiler probably will continue some showers into far
northwest IL after daybreak...with a lesser chance of reaching
north central IL.

A warm day is again on tap with 850mb temps again of 13C to 15C.
Surface winds will be more southwest today and steer in higher dew
points likely to reach the lower 60s by late today in north
central IL and elsewhere later this evening. This may make the
air mass slightly more difficult to warm and some clouds west of
I-55 will likely keep readings a few degrees shy of yesterdays.
Eastern areas should peak similar to yesterday with mid 80s.

While the front itself will remain well northwest of the CWA
today...gradually increasing convergence across eastern IA into
southern WI might be enough to spark late day/evening isolated
storms that could move into north central IL. Have maintained low
chances for that. While instability may peak in excess of 1000
J/KG...bulk shear remains low in the absence of any noteworthy
short wave...so the chance for anything severe is low.

Later tonight as a surface low strengthens in the western
Plains...warm and moist advection aloft will gradually increase.
It is possible some storms may develop in this regime...again
more favored across the western forecast area. It will be a mild
night with mid 60s forecast for lows...about 15 degrees above
normal.

MTF

&&

.LONG TERM...
329 AM CDT

Wednesday through Monday...

Southwest upper flow will prevail through this period keeping
temperatures above normal as well as multiple chances for storms.
Timing of these chances is fairly difficult...though it appears on
Wednesday that the afternoon and/or evening look to have the best
storm chances in nearly two weeks. The severe threat continues
low...greater than today/tonight...but still low. Have also
increased temperatures on Thursday which could see upper 80s to an
isolated 90 if sunshine prevails.

By Wednesday morning model solutions are in decent agreement of
the surface boundary being over southern WI or so...possibly lake
enhanced into far northeast IL. This is expected to lift northward
as a warm front with dew points in the mid 60s areawide...allowing
for MLCAPE values to peak around 1500 J/kg depending on just how
warm we reach /low to mid 80s expected/. The upper flow is
unsettled with a modest agreement in guidance of a low-amplitude
shortwave tracking over the area during the mid-afternoon to mid-
evening. This would be an ideal time for convective development if
it were to pan out. Shear values are much better further west of
the CWA and thus storm organization/intensity over our area may
struggle...but coverage still looks enough to warrant likely PoPs
in most of the CWA. Isolated severe storms with a brief wind/hail
threat could occur.

There appears to be a lull in much forcing during the day Thursday
with a capped environment likely temporarily be in place. Given
the nature of Wednesdays system...not expecting much for
lingering cloud cover...so Thursday could be quite mild. The 925mb
temperatures are forecast to be 20C to 23C. In the past 30 years
when 925mb temperatures have been this warm in northern Illinois
during late May...Chicago has had a mean high of 86 degrees. This
is why could see an isolated 90 or two for highs mainly in north
central IL if uncontaminated warming can occur.

Thursday evening and overnight the forcing for convection beings
to re-increase as the southern upper low of the western
trough...now over CA/NV...progresses into the Plains. A lot of
uncertainty on how far east forcing will be Thursday Night but
a few of the storms could be stout if they do form over the area.
Chances for rain continue through Friday and again may be higher
west depending on the track of the upper low and its forcing.
While chances for storms are in the forecast daily through the
Holiday weekend...it is a pattern that resembles a summer
one...i.e. it is not a pattern for widespread rain and refinement
in timing/details will improve as the week moves along.

MTF

&&

.AVIATION...
FOR THE 12Z TAFS...

632 am...Main forecast concern remains thunderstorm potential and
much of this period is expected to be dry. Activity northwest of
the Quad Cities continues to weaken and should dissipate before
reaching rfd...possibly with a few brief sprinkles mid morning.
Otherwise...focus shifts to late afternoon/early evening across
eastern IA/far northwest IL and southern WI where isolated to
scattered thunderstorms will be possible. Confidence remains low
but maintained the short prob30 at rfd for now. Possible later
forecasts will be able to go dry. There will be another chance of
showers and thunderstorms late tonight into Wednesday morning but
once again stayed dry with expected isolated coverage combined
with low confidence.

Light southerly winds will turn more south/southwest this morning
and with a slightly tighter gradient along with some mixing by
mid/late morning should allow speeds to increase into the 10-15kt
range. Some higher gusts will be possible but low confidence if
gusts will become prevailing. Speeds diminish this evening with
winds becoming more southerly overnight and possibly southeasterly
Wednesday morning.

Low level moisture will increase today and tonight with the
potential for mvfr vis/light fog as well as the chance for mvfr
cigs late tonight. Confidence for cigs is low so opted for just
scattered mention. If low level moisture/dewpoints do increase as
expected...better chance for some light fog by daybreak Wednesday.
cms

&&

.MARINE...

125 am...A weak cold front will slowly move southeast across
northern Lake Michigan late tonight. This front is expected to
become stationary across central portions of the lake by midday
Wednesday as low pressure begins moving north across the plains.
This front will then lift back north as a warm front Wednesday
night. As low level moisture increases across the region and
spreads over the cooler water...some fog is possible. A large
trough of low pressure is expected to persist over the plains
through early next week with prevailing southerly winds over the
lake. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSCHICAGO




000
FXUS63 KILX 241128
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
628 AM CDT TUE MAY 24 2016

.SHORT TERM...(Today)
ISSUED AT 317 AM CDT Tue May 24 2016

For today, models are not depicting any coherent disturbance to
bring any substantial lift into central IL, as a shortwave over the
Dakotas and Iowa is expected to lift northeastward likely keeping
its influence out of our area, and another on over SE Missouri to
propagate eastward through southern IL, potentially grazing Clay and
Richland counties. Nevertheless, with increasing moisture resulting
in dewpoints reaching around 60 by afternoon...enough instability
will result with afternoon heating that isolated thunderstorms could
form along any leftover boundaries from convection in the region
overnight. Therefore, have trimmed thunderstorm chances to slight
category for today SW of a Bloomington-Effingham line. With several
hundred to 1500 J/KG CAPE progged west of the Illinois River, a
few of these could become strong with hail and gusty winds,
therefore SPC has outlooked these areas in a marginal risk for
severe thunderstorms.

Otherwise...highs today should reach the low 80s today, down
marginally since Monday due to increased cloud cover, and
southerly winds around 10 mph will continue through the day.

.LONG TERM...(Tonight through Monday)
ISSUED AT 317 AM CDT Tue May 24 2016

Upper level flow from the southwest expected to persist most of the
week, with the upper low currently just south of San Francisco
expected to only reach western Kansas by Friday evening in a weaker
state. Once that low lifts northeast into the northern Plains this
weekend, another will dig southward across the western U.S. and keep
the southwest flow continuing. Net result will be an extended period
of warm and somewhat humid conditions lasting into the holiday
weekend. Individual ripples in the upper pattern will enhance rain
chances periodically, as surface boundaries to our north will not
move much. While it will not be a continuous washout, such a pattern
makes it difficult to pin down any dry periods in the forecast.
Thus, most of the forecast periods will continue to have at least a
chance of showers and thunderstorms.

Currently looks like most of this evening will be dry over the
forecast area, with an uptick in rain chances after midnight as an
MCS organizes to our northwest. GFS tracks its remnants more or less
on top of us, while the ECMWF and NAM keep most of them to our
north. Another thunderstorm cluster more likely to affect the CWA
Wednesday night, and likely PoP`s were kept from about Havana-Paris
northward. Latest SPC outlooks have backed off on the severe weather
chances over our area the next few days, as while there will be
decent instability, shear parameters are rather week. However, with
precipitable water values rising to around 1.5 inches, some of the
storms will produce locally heavy rainfall.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 628 AM CDT Tue May 24 2016

Generally VFR conditions expected for the next 24 hours...although
low probabilities of thunderstorms can`t be ruled out during the
afternoon for KPIA-KSPI, and again late in the night as showers
expected to spread eastward across central IL. Southerly winds
6-12 kts will persist through the period.

&&

.ILX Watches/Warnings/Advisories...
NONE.

&&

$$

SHORT TERM...Onton
LONG TERM...Geelhart
AVIATION...Onton




000
FXUS63 KILX 240818
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
318 AM CDT TUE MAY 24 2016

.SHORT TERM...(Today)
ISSUED AT 317 AM CDT Tue May 24 2016

For today, models are not depicting any coherent disturbance to
bring any substantial lift into central IL, as a shortwave over the
Dakotas and Iowa is expected to lift northeastward likely keeping
its influence out of our area, and another on over SE Missouri to
propagate eastward through southern IL, potentially grazing Clay and
Richland counties. Nevertheless, with increasing moisture resulting
in dewpoints reaching around 60 by afternoon...enough instability
will result with afternoon heating that isolated thunderstorms could
form along any leftover boundaries from convection in the region
overnight. Therefore, have trimmed thunderstorm chances to slight
category for today SW of a Bloomington-Effingham line. With several
hundred to 1500 J/KG CAPE progged west of the Illinois River, a
few of these could become strong with hail and gusty winds,
therefore SPC has outlooked these areas in a marginal risk for
severe thunderstorms.

Otherwise...highs today should reach the low 80s today, down
marginally since Monday due to increased cloud cover, and
southerly winds around 10 mph will continue through the day.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 317 AM CDT Tue May 24 2016

Upper level flow from the southwest expected to persist most of the
week, with the upper low currently just south of San Francisco
expected to only reach western Kansas by Friday evening in a weaker
state. Once that low lifts northeast into the northern Plains this
weekend, another will dig southward across the western U.S. and keep
the southwest flow continuing. Net result will be an extended period
of warm and somewhat humid conditions lasting into the holiday
weekend. Individual ripples in the upper pattern will enhance rain
chances periodically, as surface boundaries to our north will not
move much. While it will not be a continuous washout, such a pattern
makes it difficult to pin down any dry periods in the forecast.
Thus, most of the forecast periods will continue to have at least a
chance of showers and thunderstorms.

Currently looks like most of this evening will be dry over the
forecast area, with an uptick in rain chances after midnight as an
MCS organizes to our northwest. GFS tracks its remnants more or less
on top of us, while the ECMWF and NAM keep most of them to our
north. Another thunderstorm cluster more likely to affect the CWA
Wednesday night, and likely PoP`s were kept from about Havana-Paris
northward. Latest SPC outlooks have backed off on the severe weather
chances over our area the next few days, as while there will be
decent instability, shear parameters are rather week. However, with
precipitable water values rising to around 1.5 inches, some of the
storms will produce locally heavy rainfall.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1128 PM CDT Mon May 23 2016

Another mostly quiet 06Z aviation weather period across the
central Illinois terminals. Southerly winds will persist through
the period. A stray shower or thunderstorm can`t be ruled out
after sunrise Tuesday, especially west toward KPIA & KSPI, but
the probability is too low to carry in the TAFs at this time.
Assuming no rainfall occurs, VFR conditions will persist.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Onton
LONG TERM...Geelhart
AVIATION...Bak




000
FXUS63 KLOT 240625
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
125 AM CDT TUE MAY 24 2016

.UPDATE...
750 PM CDT

Couple tweaks to going forecast. First, removed pops western CWA
late tonight. Evening soundings from ILX/DVN both showed a very
dry air mass in place across the region. Upper ridge axis is over
the region...so thinking the activity in western Iowa should be
shunted north into MN and not pose much threat here overnight.
PWATs are progged to increase tomorrow as moisture axis flops
eastward, so threat for some sctd showers and thunderstorms will
will slowly ramp up by afternoon, especially western CWA. Grids
for tomorrow have been updated to lower pops some and also delay
arrival. Other tweak to going forecast was to lower low temps
tonight just a smidge over mainly eastern CWA. Dewpoints remain
very low and skies largely clear besides a bit of cirrus spilling
over top the upper ridge, so given the trend of the past couple
nights with lows really tanking in the dry air felt comfortable
dropping lows just a bit.

Updated forecast has been sent.

Izzi

&&

.SHORT TERM...
211 PM CDT

Through Tonight...

With a dry air mass and ample sunshine, temperatures across the
region are expected to rise into the lower to middle 80s this
afternoon.  A lake breeze boundary is slowly pushing inland this
afternoon and the IL lakefront never had the opportunity to warm up,
with the temperature at Northerly Island only reaching 64 F.  High
pressure centered over the eastern Great Lakes will continue to
slowly move to the east tonight as a cold front and associated sfc
trough approach the Middle and Upper Mississippi Valleys.  Low level
synoptic scale flow will gradually veer from Sexy to SWLY
overnight...bringing slightly higher sfc dewpoints and
increasing deep layer moisture into the WRN parts of the CWA by early
tomorrow morning, with the moister air reaching the I-39 corridor.
The increase in deep layer moisture will inhibit cooling overnight
tonight and min temps tomorrow morning should range from around 60 F
along the I-39 corridor to the lower to middle 50s over NWRN IN.
Showers and thunderstorms have developed over WRN IA/MO this
afternoon and should continue to slowly move to the east this
evening. A gradual increase elevated instability in the environment
ahead of the approaching sfc trough will keep the potential for some
convective activity to reach the Rockford area during the early
morning hours.  However...some of the guidance is suggesting that
there could be a decreasing trend to the convection during the
pre- dawn hours and then increase through the day tomorrow. So,
have maintained the increasing PoP trend during the late night
hours over the WRN portions of the CWA, but will cap PoPs in the
slight chance to chance range with a slight chance of thunder

Krein

&&

.LONG TERM...
219 PM CDT

Tuesday through Monday...

Orientation of current upper level ridge pattern will generally be
maintained for several days into the extended period as a SW
subtropical jet seen on WV imagery comes onshore near the Baja
Peninsula. Left exit region dynamics of this jet will help spawn low
pressure over the Central Plains and will be the main weather player
for the middle of this week.

The end of a 10-day dry spell will come midweek as low
pressure and a frontal boundary approach from the west on Tuesday.
Column saturation appears to take place quickly in the late morning
to afternoon...although favored areas for rain will be along the
front orientated NE to SW across the CWA. There is a small chance for
thunder to accompany the rain Tuesday...but convective indices are
very low-end. Showalter and lifted indices of -1 along with weak
effective shear and CAPE values under 500 J/KG will keep the thunder
threat very small and severe threat less than marginal values.
Warmth of 80F will continue during the mid-week as H85 temps
continue to warm-advect at 13-15c both Tuesday and Wednesday.

The cold front that moves through Tuesday night will continue to
bring precip chances. That front will lift back north as a warm front
on Wednesday. This will amplify the above listed indices to provide
a much stronger threat for thunderstorms and possible severe
weather. The warm H85 conditions will now be accompanied by an
effective moisture transport thanks to the 45kt LLJ. Expect
dewpoints in the mid-60s Wednesday which will help CAPE values rise
to above 2500 J/KG. Showalter and LI improve to -4C as well
Wednesday. 0-6km bulk shear remains at 20kt...so there is a limiting
factor to sustaining TS activity.

Warm SW flow continues on Thursday and the 850mb temps jump
to 18C. This also looks to be the one day with lower pops and sky
cover as NE IL remains in the warm sector ahead of another cold
front. These factors led to a 3 degree increase in the max temp
forecast to the mid-80s. Would not be surprised to see our first 90F
day of the season on Thursday given several hours of sunshine and
925mb temps of 24C. Unsettled weather continues through the weekend
as dewpoints stay up in the mid 60s with max temps near 80. There
will be a chance for convection each day with the main limiting
ingredient being just a trigger in the form of outflows...lake
breezes...or surface convergence.

MM

&&

.AVIATION...
FOR THE 06Z TAFS...

1210 am...Main concern this period is potential for thunderstorms
which appears to be mainly for rfd and far northwest IL. High
pressure remains over portions of the Ohio Valley and has slowed
the progression of thunderstorms over the plains. Models continue
with this trend suggesting that much of the area will be dry
through late tonight with the exception of possible convection
firing from eastern IA into southern WI later this afternoon into
this evening. If this were to occur...best timing for rfd will
likely be centered around 00z. Still fairly low confidence but
opted to maintain prob30 mention and adjust hours to currently
expected best timing. For the rest of the terminals...confidence
is low and expected coverage of anything that may develop is also
low and have continued dry forecast. There may be additional
isolated/scattered activity late tonight into Wednesday morning
but confidence here remains low.

Light south/southeasterly winds will turn more southerly or south/
southwesterly by morning. Wind speeds then increase into the
10-15kt range by mid/late morning and there could be a few higher
gusts at times. Low level winds currently in the 30-40kt range but
forecast soundings suggest these will diminish some by sunrise and
shortened duration of low level wind shear. cms

&&

.MARINE...

125 am...A weak cold front will slowly move southeast across
northern Lake Michigan late tonight. This front is expected to
become stationary across central portions of the lake by midday
Wednesday as low pressure begins moving north across the plains.
This front will then lift back north as a warm front Wednesday
night. As low level moisture increases across the region and
spreads over the cooler water...some fog is possible. A large
trough of low pressure is expected to persist over the plains
through early next week with prevailing southerly winds over the
lake. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO




000
FXUS63 KLOT 240510
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1210 AM CDT TUE MAY 24 2016

.UPDATE...
750 PM CDT

Couple tweaks to going forecast. First, removed pops western CWA
late tonight. Evening soundings from ILX/DVN both showed a very
dry air mass in place across the region. Upper ridge axis is over
the region...so thinking the activity in western Iowa should be
shunted north into MN and not pose much threat here overnight.
PWATs are progged to increase tomorrow as moisture axis flops
eastward, so threat for some sctd showers and thunderstorms will
will slowly ramp up by afternoon, especially western CWA. Grids
for tomorrow have been updated to lower pops some and also delay
arrival. Other tweak to going forecast was to lower low temps
tonight just a smidge over mainly eastern CWA. Dewpoints remain
very low and skies largely clear besides a bit of cirrus spilling
over top the upper ridge, so given the trend of the past couple
nights with lows really tanking in the dry air felt comfortable
dropping lows just a bit.

Updated forecast has been sent.

Izzi

&&

.SHORT TERM...
211 PM CDT

Through Tonight...

With a dry air mass and ample sunshine, temperatures across the
region are expected to rise into the lower to middle 80s this
afternoon.  A lake breeze boundary is slowly pushing inland this
afternoon and the IL lakefront never had the opportunity to warm up,
with the temperature at Northerly Island only reaching 64 F.  High
pressure centered over the eastern Great Lakes will continue to
slowly move to the east tonight as a cold front and associated sfc
trough approach the Middle and Upper Mississippi Valleys.  Low level
synoptic scale flow will gradually veer from Sexy to SWLY
overnight...bringing slightly higher sfc dewpoints and
increasing deep layer moisture into the WRN parts of the CWA by early
tomorrow morning, with the moister air reaching the I-39 corridor.
The increase in deep layer moisture will inhibit cooling overnight
tonight and min temps tomorrow morning should range from around 60 F
along the I-39 corridor to the lower to middle 50s over NWRN IN.
Showers and thunderstorms have developed over WRN IA/MO this
afternoon and should continue to slowly move to the east this
evening. A gradual increase elevated instability in the environment
ahead of the approaching sfc trough will keep the potential for some
convective activity to reach the Rockford area during the early
morning hours.  However...some of the guidance is suggesting that
there could be a decreasing trend to the convection during the
pre- dawn hours and then increase through the day tomorrow. So,
have maintained the increasing PoP trend during the late night
hours over the WRN portions of the CWA, but will cap PoPs in the
slight chance to chance range with a slight chance of thunder

Krein

&&

.LONG TERM...
219 PM CDT

Tuesday through Monday...

Orientation of current upper level ridge pattern will generally be
maintained for several days into the extended period as a SW
subtropical jet seen on WV imagery comes onshore near the Baja
Peninsula. Left exit region dynamics of this jet will help spawn low
pressure over the Central Plains and will be the main weather player
for the middle of this week.

The end of a 10-day dry spell will come midweek as low
pressure and a frontal boundary approach from the west on Tuesday.
Column saturation appears to take place quickly in the late morning
to afternoon...although favored areas for rain will be along the
front orientated NE to SW across the CWA. There is a small chance for
thunder to accompany the rain Tuesday...but convective indices are
very low-end. Showalter and lifted indices of -1 along with weak
effective shear and CAPE values under 500 J/KG will keep the thunder
threat very small and severe threat less than marginal values.
Warmth of 80F will continue during the mid-week as H85 temps
continue to warm-advect at 13-15c both Tuesday and Wednesday.

The cold front that moves through Tuesday night will continue to
bring precip chances. That front will lift back north as a warm front
on Wednesday. This will amplify the above listed indices to provide
a much stronger threat for thunderstorms and possible severe
weather. The warm H85 conditions will now be accompanied by an
effective moisture transport thanks to the 45kt LLJ. Expect
dewpoints in the mid-60s Wednesday which will help CAPE values rise
to above 2500 J/KG. Showalter and LI improve to -4C as well
Wednesday. 0-6km bulk shear remains at 20kt...so there is a limiting
factor to sustaining TS activity.

Warm SW flow continues on Thursday and the 850mb temps jump
to 18C. This also looks to be the one day with lower pops and sky
cover as NE IL remains in the warm sector ahead of another cold
front. These factors led to a 3 degree increase in the max temp
forecast to the mid-80s. Would not be surprised to see our first 90F
day of the season on Thursday given several hours of sunshine and
925mb temps of 24C. Unsettled weather continues through the weekend
as dewpoints stay up in the mid 60s with max temps near 80. There
will be a chance for convection each day with the main limiting
ingredient being just a trigger in the form of outflows...lake
breezes...or surface convergence.

MM

&&

.AVIATION...
FOR THE 06Z TAFS...

1210 am...Main concern this period is potential for thunderstorms
which appears to be mainly for rfd and far northwest IL. High
pressure remains over portions of the Ohio Valley and has slowed
the progression of thunderstorms over the plains. Models continue
with this trend suggesting that much of the area will be dry
through late tonight with the exception of possible convection
firing from eastern IA into southern WI later this afternoon into
this evening. If this were to occur...best timing for rfd will
likely be centered around 00z. Still fairly low confidence but
opted to maintain prob30 mention and adjust hours to currently
expected best timing. For the rest of the terminals...confidence
is low and expected coverage of anything that may develop is also
low and have continued dry forecast. There may be additional
isolated/scattered activity late tonight into Wednesday morning
but confidence here remains low.

Light south/southeasterly winds will turn more southerly or south/
southwesterly by morning. Wind speeds then increase into the
10-15kt range by mid/late morning and there could be a few higher
gusts at times. Low level winds currently in the 30-40kt range but
forecast soundings suggest these will diminish some by sunrise and
shortened duration of low level wind shear. cms

&&

.MARINE...
219 PM CDT

South winds at 15-25kt continue across much of Lake Michigan through
tonight. A cold front will drop southward across the lake Tuesday
night and shift winds to a northerly direction. The front may stall
across the lake on Wednesday...offering convergent winds near the
south buoy. By early Thursday...the front should lift back north
as a warm front which will shift winds back to a southerly
direction. Thunderstorms will be possible each day across the lake
with the best chance being Wednesday into Thursday along the frontal
boundary. South winds are expected for several days into the weekend
with waves not becoming particularly high.

MM

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO




000
FXUS63 KILX 240430
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1130 PM CDT MON MAY 23 2016

.UPDATE...
Issued at 855 PM CDT Mon May 23 2016

Updated forecast earlier this evening to remove PoPs for the rest
of the night, and reduce them for much of Tuesday (especially in
the morning). 00Z KILX sounding remains exceptionally dry, and the
local airmass should still remain on the dry side well into
Tuesday. Convection across the Plains and upper Midwest continues
to dissipate as it tracks east toward Illinois, and most forecast
guidances suggests this trend will continue. Given the current
lack of moisture, forcing, or instability locally, do not see any
reason to argue with the latest guidance. There are a couple MCVs
that were in our vicinity based on radar loops, the closest over
south-central Missouri, but even the precipitation with these has
largely dissipated as they have tracked east.

Otherwise, only minor tweaks were needed to the hourly trends for
most other weather parameters.

&&

.SHORT TERM...(Tonight)
ISSUED AT 245 PM CDT Mon May 23 2016

A weak but persistent frontal boundary to the west of the
Mississippi River Valley will be driving the weather through the end
of the week. Currently caught between an upper low in the northern
high plains along the Canadian border...and another over the mid
Atlantic Coast...it is expected to slowly advance eastward
overnight.  As it approaches, the region will see increasing cloud
cover with southerly winds.  Precip chances will also increase
slightly before dawn NW of the Illinois River Valley.

.LONG TERM...(Tuesday through Monday)
ISSUED AT 245 PM CDT Mon May 23 2016

The upper level ridge that brought the very pleasant weather to our
area over the past several days will begin to deamplify as it shifts
off to our east later tonight into Tuesday, allowing a moist
southwest flow to set up over the region and hold through this
forecast period. What makes the forecast tough is the fact that
any frontal boundary that would enhance the shower and thunderstorm
chances in our area is forecast to remain well out to our west and
northwest thru the period as it becomes parallel to the upper level
flow. Meanwhile, models suggest upper level ridging builds over the
eastern U.S. later in the week which will continue to funnel deep
tropical moisture northeast into the Midwest. So it comes down to
timing of individual low amplitude shortwaves ejecting out of the
mean longwave trof over the western U.S. during the next 5 days and
then trying to time thunderstorms into our forecast area.

We may see a remnant MCS track into our western areas tomorrow
morning but the further east it goes during the day, the less
support it will have to maintain itself. It still appears the better
instability and shear will be to our west tomorrow with mainly
scattered coverage expected in our area during the day. The setup
appears to become more favorable for nocturnal convection later
tomorrow night into Wednesday morning as some decent 850 mb theta-e
advection sets up just to our southwest as the low level jet veers
more into a southwest to west direction after 06z creating some
favorable moisture convergence over central Illinois. Those storms
should affect a good portion of the forecast area by dawn Wednesday
with steep 700-500 mb lapse rates but marginal, at best, deep
layer shear with values around 20 kts suggesting more of a threat
from hail and heavy rainfall as PWAT values increase to between
1.25 to 1.50 inches Wednesday morning.

After that, confidence will be rather low for timing and coverage of
additional storms on Wednesday, even though there is a distinct
shortwave that is forecast to track across the area by later in the
day Wednesday. Will the atmosphere be worked over enough from the
morning convection to prevent any redevelopment in the afternoon?
What may occur would be a situation where convection redevelops over
our area Wednesday night/Thursday morning as a 40-45 kt LLJ sets up
over central Illinois, and brings another round of storms into our
area late at night or just before dawn Thursday. Unfortunately, we
do not see any significant break in the pattern that would allow
a period or two without the chance for precip, so there will be POPs
through the upcoming holiday weekend. It certainly not a situation
that produces all day rainfall, but the potential is there for
scattered storms, some of which could be strong-severe and definitely
bring the threat for some heavy rainfall to parts of our area thru
the period. Temperatures will remain above normal through the rest
of the week and into the weekend as daytime highs should climb into
the 80s with even some early morning lows that may have a tough time
dropping below the upper 60s later this week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1128 PM CDT Mon May 23 2016

Another mostly quiet 06Z aviation weather period across the
central Illinois terminals. Southerly winds will persist through
the period. A stray shower or thunderstorm can`t be ruled out
after sunrise Tuesday, especially west toward KPIA & KSPI, but
the probability is too low to carry in the TAFs at this time.
Assuming no rainfall occurs, VFR conditions will persist.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...BAK
SHORT TERM...HJS
LONG TERM...Smith
AVIATION...BAK




000
FXUS63 KILX 240155
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
855 PM CDT MON MAY 23 2016

.UPDATE...
Issued at 855 PM CDT Mon May 23 2016

Updated forecast earlier this evening to remove PoPs for the rest
of the night, and reduce them for much of Tuesday (especially in
the morning). 00Z KILX sounding remains exceptionally dry, and the
local airmass should still remain on the dry side well into
Tuesday. Convection across the Plains and upper Midwest continues
to dissipate as it tracks east toward Illinois, and most forecast
guidances suggests this trend will continue. Given the current
lack of moisture, forcing, or instability locally, do not see any
reason to argue with the latest guidance. There are a couple MCVs
that were in our vicinity based on radar loops, the closest over
south-central Missouri, but even the precipitation with these has
largely dissipated as they have tracked east.

Otherwise, only minor tweaks were needed to the hourly trends for
most other weather parameters.

&&

.SHORT TERM...(Tonight)
ISSUED AT 245 PM CDT Mon May 23 2016

A weak but persistent frontal boundary to the west of the
Mississippi River Valley will be driving the weather through the end
of the week. Currently caught between an upper low in the northern
high plains along the Canadian border...and another over the mid
Atlantic Coast...it is expected to slowly advance eastward
overnight.  As it approaches, the region will see increasing cloud
cover with southerly winds.  Precip chances will also increase
slightly before dawn NW of the Illinois River Valley.

.LONG TERM...(Tuesday through Monday)
ISSUED AT 245 PM CDT Mon May 23 2016

The upper level ridge that brought the very pleasant weather to our
area over the past several days will begin to deamplify as it shifts
off to our east later tonight into Tuesday, allowing a moist
southwest flow to set up over the region and hold through this
forecast period. What makes the forecast tough is the fact that
any frontal boundary that would enhance the shower and thunderstorm
chances in our area is forecast to remain well out to our west and
northwest thru the period as it becomes parallel to the upper level
flow. Meanwhile, models suggest upper level ridging builds over the
eastern U.S. later in the week which will continue to funnel deep
tropical moisture northeast into the Midwest. So it comes down to
timing of individual low amplitude shortwaves ejecting out of the
mean longwave trof over the western U.S. during the next 5 days and
then trying to time thunderstorms into our forecast area.

We may see a remnant MCS track into our western areas tomorrow
morning but the further east it goes during the day, the less
support it will have to maintain itself. It still appears the better
instability and shear will be to our west tomorrow with mainly
scattered coverage expected in our area during the day. The setup
appears to become more favorable for nocturnal convection later
tomorrow night into Wednesday morning as some decent 850 mb theta-e
advection sets up just to our southwest as the low level jet veers
more into a southwest to west direction after 06z creating some
favorable moisture convergence over central Illinois. Those storms
should affect a good portion of the forecast area by dawn Wednesday
with steep 700-500 mb lapse rates but marginal, at best, deep
layer shear with values around 20 kts suggesting more of a threat
from hail and heavy rainfall as PWAT values increase to between
1.25 to 1.50 inches Wednesday morning.

After that, confidence will be rather low for timing and coverage of
additional storms on Wednesday, even though there is a distinct
shortwave that is forecast to track across the area by later in the
day Wednesday. Will the atmosphere be worked over enough from the
morning convection to prevent any redevelopment in the afternoon?
What may occur would be a situation where convection redevelops over
our area Wednesday night/Thursday morning as a 40-45 kt LLJ sets up
over central Illinois, and brings another round of storms into our
area late at night or just before dawn Thursday. Unfortunately, we
do not see any significant break in the pattern that would allow
a period or two without the chance for precip, so there will be POPs
through the upcoming holiday weekend. It certainly not a situation
that produces all day rainfall, but the potential is there for
scattered storms, some of which could be strong-severe and definitely
bring the threat for some heavy rainfall to parts of our area thru
the period. Temperatures will remain above normal through the rest
of the week and into the weekend as daytime highs should climb into
the 80s with even some early morning lows that may have a tough time
dropping below the upper 60s later this week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 653 PM CDT Mon May 23 2016

Another mostly quiet 00Z aviation weather period across the
central Illinois terminals. Southerly winds will persist through
the period. A stray shower or thunderstorm can`t be ruled out
during the day Tuesday, especially west toward KPIA & KSPI, but
the probability is too low to carry in the TAFs at this time.
Assuming no rainfall occurs, VFR conditions will persist.


&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...BAK
SHORT TERM...HJS
LONG TERM...Smith
AVIATION...BAK




000
FXUS63 KLOT 240052
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
752 PM CDT MON MAY 23 2016

.UPDATE...
750 PM CDT

Couple tweaks to going forecast. First, removed pops western CWA
late tonight. Evening soundings from ILX/DVN both showed a very
dry air mass in place across the region. Upper ridge axis is over
the region...so thinking the activity in western Iowa should be
shunted north into MN and not pose much threat here overnight.
PWATs are progged to increase tomorrow as moisture axis flops
eastward, so threat for some sctd showers and thunderstorms will
will slowly ramp up by afternoon, especially western CWA. Grids
for tomorrow have been updated to lower pops some and also delay
arrival. Other tweak to going forecast was to lower low temps
tonight just a smidge over mainly eastern CWA. Dewpoints remain
very low and skies largely clear besides a bit of cirrus spilling
over top the upper ridge, so given the trend of the past couple
nights with lows really tanking in the dry air felt comfortable
dropping lows just a bit.

Updated forecast has been sent.

Izzi

&&

.SHORT TERM...
211 PM CDT

Through Tonight...

With a dry air mass and ample sunshine, temperatures across the
region are expected to rise into the lower to middle 80s this
afternoon.  A lake breeze boundary is slowly pushing inland this
afternoon and the IL lakefront never had the opportunity to warm up,
with the temperature at Northerly Island only reaching 64 F.  High
pressure centered over the eastern Great Lakes will continue to
slowly move to the east tonight as a cold front and associated sfc
trough approach the Middle and Upper Mississippi Valleys.  Low level
synoptic scale flow will gradually veer from Sexy to SWLY
overnight...bringing slightly higher sfc dewpoints and
increasing deep layer moisture into the WRN parts of the CWA by early
tomorrow morning, with the moister air reaching the I-39 corridor.
The increase in deep layer moisture will inhibit cooling overnight
tonight and min temps tomorrow morning should range from around 60 F
along the I-39 corridor to the lower to middle 50s over NWRN IN.
Showers and thunderstorms have developed over WRN IA/MO this
afternoon and should continue to slowly move to the east this
evening. A gradual increase elevated instability in the environment
ahead of the approaching sfc trough will keep the potential for some
convective activity to reach the Rockford area during the early
morning hours.  However...some of the guidance is suggesting that
there could be a decreasing trend to the convection during the
pre- dawn hours and then increase through the day tomorrow. So,
have maintained the increasing PoP trend during the late night
hours over the WRN portions of the CWA, but will cap PoPs in the
slight chance to chance range with a slight chance of thunder

Krein

&&

.LONG TERM...
219 PM CDT

Tuesday through Monday...

Orientation of current upper level ridge pattern will generally be
maintained for several days into the extended period as a SW
subtropical jet seen on WV imagery comes onshore near the Baja
Peninsula. Left exit region dynamics of this jet will help spawn low
pressure over the Central Plains and will be the main weather player
for the middle of this week.

The end of a 10-day dry spell will come midweek as low
pressure and a frontal boundary approach from the west on Tuesday.
Column saturation appears to take place quickly in the late morning
to afternoon...although favored areas for rain will be along the
front orientated NE to SW across the CWA. There is a small chance for
thunder to accompany the rain Tuesday...but convective indices are
very low-end. Showalter and lifted indices of -1 along with weak
effective shear and CAPE values under 500 J/KG will keep the thunder
threat very small and severe threat less than marginal values.
Warmth of 80F will continue during the mid-week as H85 temps
continue to warm-advect at 13-15c both Tuesday and Wednesday.

The cold front that moves through Tuesday night will continue to
bring precip chances. That front will lift back north as a warm front
on Wednesday. This will amplify the above listed indices to provide
a much stronger threat for thunderstorms and possible severe
weather. The warm H85 conditions will now be accompanied by an
effective moisture transport thanks to the 45kt LLJ. Expect
dewpoints in the mid-60s Wednesday which will help CAPE values rise
to above 2500 J/KG. Showalter and LI improve to -4C as well
Wednesday. 0-6km bulk shear remains at 20kt...so there is a limiting
factor to sustaining TS activity.

Warm SW flow continues on Thursday and the 850mb temps jump
to 18C. This also looks to be the one day with lower pops and sky
cover as NE IL remains in the warm sector ahead of another cold
front. These factors led to a 3 degree increase in the max temp
forecast to the mid-80s. Would not be surprised to see our first 90F
day of the season on Thursday given several hours of sunshine and
925mb temps of 24C. Unsettled weather continues through the weekend
as dewpoints stay up in the mid 60s with max temps near 80. There
will be a chance for convection each day with the main limiting
ingredient being just a trigger in the form of outflows...lake
breezes...or surface convergence.

MM

&&

.AVIATION...
For the 00Z TAFS...

Lake breeze should make it through ORD shortly after 00Z with an
expected wind shift to east before winds ease late this evening
and gradually become light south. Winds should pick up a bit by
mid-late morning Tuesday from the south with no lake breeze
expected at the terminals. Very small chance of shra/tsra tomorrow
afternoon...but threat appears too low to include in Chicago area
terminals. Did keep a PROB30 for RFD in the afternoon where
chances are best...though still pretty low.

Izzi

&&

.MARINE...
219 PM CDT

South winds at 15-25kt continue across much of Lake Michigan through
tonight. A cold front will drop southward across the lake Tuesday
night and shift winds to a northerly direction. The front may stall
across the lake on Wednesday...offering convergent winds near the
south buoy. By early Thursday...the front should lift back north
as a warm front which will shift winds back to a southerly
direction. Thunderstorms will be possible each day across the lake
with the best chance being Wednesday into Thursday along the frontal
boundary. South winds are expected for several days into the weekend
with waves not becoming particularly high.

MM

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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000
FXUS63 KILX 232357
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
657 PM CDT MON MAY 23 2016

.SHORT TERM...(Tonight)
ISSUED AT 245 PM CDT Mon May 23 2016

A weak but persistent frontal boundary to the west of the
Mississippi River Valley will be driving the weather through the end
of the week. Currently caught between an upper low in the northern
high plains along the Canadian border...and another over the mid
Atlantic Coast...it is expected to slowly advance eastward
overnight.  As it approaches, the region will see increasing cloud
cover with southerly winds.  Precip chances will also increase
slightly before dawn NW of the Illinois River Valley.

.LONG TERM...(Tuesday through Monday)
ISSUED AT 245 PM CDT Mon May 23 2016

The upper level ridge that brought the very pleasant weather to our
area over the past several days will begin to deamplify as it shifts
off to our east later tonight into Tuesday, allowing a moist
southwest flow to set up over the region and hold through this
forecast period. What makes the forecast tough is the fact that
any frontal boundary that would enhance the shower and thunderstorm
chances in our area is forecast to remain well out to our west and
northwest thru the period as it becomes parallel to the upper level
flow. Meanwhile, models suggest upper level ridging builds over the
eastern U.S. later in the week which will continue to funnel deep
tropical moisture northeast into the Midwest. So it comes down to
timing of individual low amplitude shortwaves ejecting out of the
mean longwave trof over the western U.S. during the next 5 days and
then trying to time thunderstorms into our forecast area.

We may see a remnant MCS track into our western areas tomorrow
morning but the further east it goes during the day, the less
support it will have to maintain itself. It still appears the better
instability and shear will be to our west tomorrow with mainly
scattered coverage expected in our area during the day. The setup
appears to become more favorable for nocturnal convection later
tomorrow night into Wednesday morning as some decent 850 mb theta-e
advection sets up just to our southwest as the low level jet veers
more into a southwest to west direction after 06z creating some
favorable moisture convergence over central Illinois. Those storms
should affect a good portion of the forecast area by dawn Wednesday
with steep 700-500 mb lapse rates but marginal, at best, deep
layer shear with values around 20 kts suggesting more of a threat
from hail and heavy rainfall as PWAT values increase to between
1.25 to 1.50 inches Wednesday morning.

After that, confidence will be rather low for timing and coverage of
additional storms on Wednesday, even though there is a distinct
shortwave that is forecast to track across the area by later in the
day Wednesday. Will the atmosphere be worked over enough from the
morning convection to prevent any redevelopment in the afternoon?
What may occur would be a situation where convection redevelops over
our area Wednesday night/Thursday morning as a 40-45 kt LLJ sets up
over central Illinois, and brings another round of storms into our
area late at night or just before dawn Thursday. Unfortunately, we
do not see any significant break in the pattern that would allow
a period or two without the chance for precip, so there will be POPs
through the upcoming holiday weekend. It certainly not a situation
that produces all day rainfall, but the potential is there for
scattered storms, some of which could be strong-severe and definitely
bring the threat for some heavy rainfall to parts of our area thru
the period. Temperatures will remain above normal through the rest
of the week and into the weekend as daytime highs should climb into
the 80s with even some early morning lows that may have a tough time
dropping below the upper 60s later this week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 653 PM CDT Mon May 23 2016

Another mostly quiet 00Z aviation weather period across the
central Illinois terminals. Southerly winds will persist through
the period. A stray shower or thunderstorm can`t be ruled out
during the day Tuesday, especially west toward KPIA & KSPI, but
the probability is too low to carry in the TAFs at this time.
Assuming no rainfall occurs, VFR conditions will persist.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...HJS
LONG TERM...Smith
AVIATION...BAK




000
FXUS63 KLOT 232347 CCA
AFDLOT

Area Forecast Discussion...CORRECTED
National Weather Service Chicago/Romeoville, IL
647 PM CDT MON MAY 23 2016

.SHORT TERM...
211 PM CDT

Through Tonight...

With a dry airmass and ample sunshine, temperatures across the
region are expected to rise into the lower to middle 80s this
afternoon.  A lake breeze boundary is slowly pushing inland this
afternoon and the IL lakefront never had the opportunity to warm up,
with the temperature at Northerly Island only reaching 64 F.  High
pressure centered over the eastern Great Lakes will continue to
slowly move to the east tonight as a cold front and associated sfc
trough approach the Middle and Upper Mississippi Valleys.  Low level
synoptic scale flow will gradually veer from SELY to SWLY
overnight...bringing slightly higher sfc dewpoints and
increasing deep layer moisture into the WRN parts of the CWA by early
tomorrow morning, with the moister air reaching the I-39 corridor.
The increase in deep layer moisture will inhibit cooling overnight
tonight and min temps tomorrow morning should range from around 60 F
along the I-39 corridor to the lower to middle 50s over NWRN IN.
Showers and thunderstorms have developed over WRN IA/MO this
afternoon and should continue to slowly move to the east this
evening. A gradual increase elevated instability in the environment
ahead of the approaching sfc trough will keep the potential for some
convective activity to reach the Rockford area during the early
morning hours.  However...some of the guidance is suggesting that
there could be a decreasing trend to the convection durg the pre-
dawn hours and then increase through the day tomorrow.  So, have
maintained the increasing PoP trend during the late night hours over
the WRN portions of the CWA, but will cap PoPs in the slight chance
to chance range with a slight chance of thunder

Krein

&&

.LONG TERM...
219 PM CDT

Tuesday through Monday...

Orientation of current upper level ridge pattern will generally be
maintained for several days into the extended period as a SW
subtropical jet seen on WV imagery comes onshore near the Baja
Peninsula. Left exit region dynamics of this jet will help spawn low
pressure over the Central Plains and will be the main weather player
for the middle of this week.

The end of a 10-day dry spell will come midweek as low
pressure and a frontal boundary approach from the west on Tuesday.
Column saturation appears to take place quickly in the late morning
to afternoon...although favored areas for rain will be along the
front orientated NE to SW across the CWA. There is a small chance for
thunder to accompany the rain Tuesday...but convective indices are
very low-end. Showalter and lifted indices of -1 along with weak
effective shear and CAPE values under 500 J/KG will keep the thunder
threat very small and severe threat less than marginal values.
Warmth of 80F will continue during the mid-week as H85 temps
continue to warm-advect at 13-15c both Tuesday and Wednesday.

The cold front that moves through Tuesday night will continue to
bring precip chances. That front will lift back north as a warm front
on Wednesday. This will amplify the above listed indices to provide
a much stronger threat for thunderstorms and possible severe
weather. The warm H85 conditions will now be accompanied by an
effective moisture transport thanks to the 45kt LLJ. Expect
dewpoints in the mid-60s Wednesday which will help CAPE values rise
to above 2500 J/KG. Showalter and LI improve to -4C as well
Wednesday. 0-6km bulk shear remains at 20kt...so there is a limiting
factor to sustaining TS activity.

Warm SW flow continues on Thursday and the 850mb temps jump
to 18C. This also looks to be the one day with lower pops and sky
cover as NE IL remains in the warm sector ahead of another cold
front. These factors led to a 3 degree increase in the max temp
forecast to the mid-80s. Would not be surprised to see our first 90F
day of the season on Thursday given several hours of sunshine and
925mb temps of 24C. Unsettled weather continues through the weekend
as dewpoints stay up in the mid 60s with max temps near 80. There
will be a chance for convection each day with the main limiting
ingredient being just a trigger in the form of outflows...lake
breezes...or surface convergence.

MM

&&

.AVIATION...
For the 00Z TAFS...

Lake breeze should make it through ORD shortly after 00Z with an
expected wind shift to east before winds ease late this evening
and gradually become light south. Winds should pick up a bit by
mid-late morning Tuesday from the south with no lake breeze
expected at the terminals. Very small chance of shra/tsra tomorrow
afternoon...but threat appears too low to include in Chicago area
terminals. Did keep a PROB30 for RFD in the afternoon where
chances are best...though still pretty low.

Izzi

&&

.MARINE...
219 PM CDT

South winds at 15-25kt continue across much of Lake Michigan through
tonight. A cold front will drop southward across the lake Tuesday
night and shift winds to a northerly direction. The front may stall
across the lake on Wednesday...offering convergent winds near the
south buoy. By early Thursday...the front should lift back north
as a warm front which will shift winds back to a southerly
direction. Thunderstorms will be possible each day across the lake
with the best chance being Wednesday into Thursday along the frontal
boundary. South winds are expected for several days into the weekend
with waves not becoming particularly high.

MM

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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000
FXUS63 KLOT 232339
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
639 PM CDT MON MAY 23 2016

.SHORT TERM...
211 PM CDT

Through Tonight...

With a dry airmass and ample sunshine, temperatures across the
region are expected to rise into the lower to middle 80s this
afternoon.  A lake breeze boundary is slowly pushing inland this
afternoon and the IL lakefront never had the opportunity to warm up,
with the temperature at Northerly Island only reaching 64 F.  High
pressure centered over the eastern Great Lakes will continue to
slowly move to the east tonight as a cold front and associated sfc
trough approach the Middle and Upper Mississippi Valleys.  Low level
synoptic scale flow will gradually veer from SELY to SWLY
overnight...bringing slightly higher sfc dewpoints and
increasing deep layer moisture into the WRN parts of the CWA by early
tomorrow morning, with the moister air reaching the I-39 corridor.
The increase in deep layer moisture will inhibit cooling overnight
tonight and min temps tomorrow morning should range from around 60 F
along the I-39 corridor to the lower to middle 50s over NWRN IN.
Showers and thunderstorms have developed over WRN IA/MO this
afternoon and should continue to slowly move to the east this
evening. A gradual increase elevated instability in the environment
ahead of the approaching sfc trough will keep the potential for some
convective activity to reach the Rockford area during the early
morning hours.  However...some of the guidance is suggesting that
there could be a decreasing trend to the convection durg the pre-
dawn hours and then increase through the day tomorrow.  So, have
maintained the increasing PoP trend during the late night hours over
the WRN portions of the CWA, but will cap PoPs in the slight chance
to chance range with a slight chance of thunder

Krein

&&

.LONG TERM...
219 PM CDT

Tuesday through Monday...

Orientation of current upper level ridge pattern will generally be
maintained for several days into the extended period as a SW
subtropical jet seen on WV imagery comes onshore near the Baja
Peninsula. Left exit region dynamics of this jet will help spawn low
pressure over the Central Plains and will be the main weather player
for the middle of this week.

The end of a 10-day dry spell will come midweek as low
pressure and a frontal boundary approach from the west on Tuesday.
Column saturation appears to take place quickly in the late morning
to afternoon...although favored areas for rain will be along the
front orientated NE to SW across the CWA. There is a small chance for
thunder to accompany the rain Tuesday...but convective indices are
very low-end. Showalter and lifted indices of -1 along with weak
effective shear and CAPE values under 500 J/KG will keep the thunder
threat very small and severe threat less than marginal values.
Warmth of 80F will continue during the mid-week as H85 temps
continue to warm-advect at 13-15c both Tuesday and Wednesday.

The cold front that moves through Tuesday night will continue to
bring precip chances. That front will lift back north as a warm front
on Wednesday. This will amplify the above listed indices to provide
a much stronger threat for thunderstorms and possible severe
weather. The warm H85 conditions will now be accompanied by an
effective moisture transport thanks to the 45kt LLJ. Expect
dewpoints in the mid-60s Wednesday which will help CAPE values rise
to above 2500 J/KG. Showalter and LI improve to -4C as well
Wednesday. 0-6km bulk shear remains at 20kt...so there is a limiting
factor to sustaining TS activity.

Warm SW flow continues on Thursday and the 850mb temps jump
to 18C. This also looks to be the one day with lower pops and sky
cover as NE IL remains in the warm sector ahead of another cold
front. These factors led to a 3 degree increase in the max temp
forecast to the mid-80s. Would not be surprised to see our first 90F
day of the season on Thursday given several hours of sunshine and
925mb temps of 24C. Unsettled weather continues through the weekend
as dewpoints stay up in the mid 60s with max temps near 80. There
will be a chance for convection each day with the main limiting
ingredient being just a trigger in the form of outflows...lake
breezes...or surface convergence.

MM

&&

.AVIATION...
For the 00Z TAFS...

Lake breeze should make it through ORD shortly after 00Z with an
expected wind shit to east before winds ease late this evening
and gradually become light south. Winds should pick up a bit by
mid-late morning Tuesday from the south with no lake breeze
expected at the terminals. Very small chance of shra/tsra tomorrow
afternoon...but threat appears too low to include in Chicago area
terminals. Did keep a PROB30 for RFD in the afternoon where
chances are best...though still pretty low.

Izzi

&&

.MARINE...
219 PM CDT

South winds at 15-25kt continue across much of Lake Michigan through
tonight. A cold front will drop southward across the lake Tuesday
night and shift winds to a northerly direction. The front may stall
across the lake on Wednesday...offering convergent winds near the
south buoy. By early Thursday...the front should lift back north
as a warm front which will shift winds back to a southerly
direction. Thunderstorms will be possible each day across the lake
with the best chance being Wednesday into Thursday along the frontal
boundary. South winds are expected for several days into the weekend
with waves not becoming particularly high.

MM

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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000
FXUS63 KILX 231129
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
629 AM CDT MON MAY 23 2016

.SHORT TERM...(Today)
ISSUED AT 238 AM CDT Mon May 23 2016

A high pressure ridge in the mid levels today will continue to bring
clear skies. With high pressure at the surface now centered over the
eastern Ohio River Valley region, southeasterly to southerly winds
will develop to around 6-12 mph by afternoon, along with occasional
gusts 10-20 mph. The stronger winds will be toward western IL. With
moisture still relatively dry today (dewpoints near 50), highs
reaching the low to mid 80s will continue to feel relatively mild.
The warmer mid 80s will be generally west of I-57 where stronger
southerly flow advects warmer air from the south into the area.

.LONG TERM...(Tonight through Sunday)
ISSUED AT 238 AM CDT Mon May 23 2016

Upper level pattern has begun its transition to a flow more out of
the southwest, as the ridge overhead breaks down through the day.
This will lead to a more humid air mass moving in beginning on
Tuesday. With a frontal boundary becoming nearly stationary not too
far to the north, periods of showers and thunderstorms will occur
most of the week, although tonight should be largely dry except late
in the far west.

Main concern will be the potential for any strong to severe
thunderstorms through the period. While CAPE values increase
nicely across the western CWA Tuesday and Wednesday, 0-6km bulk
shear values are expected to only be around 25-30 knots,
suggesting more of an environment conducive to pulse-type
strong/severe storms. There is also some uncertainty as to the
influence on any previous convection in terms of boundaries or
ability to clear out enough to help destabilize the atmosphere.
Some indications also are seen on the ECMWF of one or more MCS
systems late in the week, especially Thursday night with the
stationary front much closer to us.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 629 AM CDT Mon May 23 2016

VFR conditions expected across the central Illinois terminals
through the 12Z TAF valid time. Low probability of thunderstorm
activity possible toward the end of the period from KSPI-KPIA
westward so have included VCTS in TAFs. Winds will trend
southeasterly with time as high pressure slowly pulls eastward
from the area. Wind speeds becoming 7-10 kts after 15Z...with late
morning/afternoon gusts to around 15 kts possible for KPIA-KSPI.
Cloud cover should be minimal through most of the forecast period,
with increasing mid and upper cloud cover late in the forecast
period.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

$$

SHORT TERM...Onton
LONG TERM...Geelhart
AVIATION...Onton




000
FXUS63 KLOT 230610
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
110 AM CDT MON MAY 23 2016

.SHORT TERM...
138 PM CDT

Through Monday Night...

Sunshine and warmth will be the main story in the near term as high
pressure is sprawled across the Great Lakes and portions of the mid
to upper Mississippi Valley. The ridge axis is centered just to
our north this afternoon allowing a light northeast breeze to keep
the lake front cooler while temperatures inland warm into the low
80s. The ridge axis will slide to our southeast overnight
allowing southerly flow to overspread the forecast area tomorrow.
Temperatures tomorrow are expected to be similar to today...except
the warmth should spread across much of the Chicago metro with
south flow. Parts of Lake County and northern Cook County will be
the main areas of concern where an afternoon lake breeze will
keep temperatures cooler.

Monday night...low level jet ramps up across portions of the mid
Missouri Valley which will be the focus for initial nocturnal
convection.  As the low level jet veers late into the overnight
hours...several models indicate that convection will spread into
northwest and north central Illinois late Monday night. With the
main instability axis focused well to our west and veering/weakening
low level jet by the time precip approaches the local area...would
anticipate any convection to be weakening if and when it enters the
CWA. Maintained some slight chance/low chance PoPs mainly along and
west of the I-39 corridor and focused them towards the pre-dawn
hours early Tuesday morning.

Deubelbeiss

&&

.LONG TERM...
217 PM CDT

Tuesday through Sunday...

Main forecast concerns/challenges are with periodic chances for
thunderstorms through the period.

The period will begin with approaching thunderstorm chances
Tuesday morning, as upper level ridge shifts to the east and as
steering flow helps to shift over more energetic flow across the
region. The stronger forcing coinciding with surface reflection
and frontal boundary will be further to the north over northern
Wisconsin Tuesday morning and even Tuesday afternoon. However,
guidance showing some thunderstorm development pushing through
eastern Iowa into west/northwest Illinois in the morning. This
scenario seems reasonable during that time, given eastward
shifting instability and moisture axis. Guidance continues to vary
to the extent of this development in the afternoon as it pushes
further east, with some guidance dry for most of the CWA in the
afternoon. Confidence lowers in the afternoon with thunderstorm
chances as it would appear any lingering development would follow
instability/moisture axis to the south of the cwa. Decent
instability and moisture in place for much of northern Illinois
would support any guidance showing thunderstorm chances for the
remaining cwa in the afternoon, and so have maintained slight
chance/chance wording for the entire cwa Tuesday afternoon. Flow
in the mid/upper levels is rather weak during this time, and think
thunderstorm organization would be limited if it occurred but with
dewpoints reaching the lower 60s and increasing instability, will
continue to monitor for the possibility for isolated strong storms
with any development Tuesday afternoon. With low confidence on
precip chances Tuesday, lower confidence with high temps as well.
However, airmass would support lower 80s, and have maintained that
in the grids.

After a possible lull in activity Tuesday evening, approaching
boundary from the north and increasing LLJ/shortwave energy will
likely support development once again later in the night into
Wednesday morning. Guidance showing frontal boundary continuing
south into northeast Illinois by Wednesday morning, with this
providing highly variable temp conditions Wednesday. Did lower
high temps for areas near the lake in northeast Illinois Wednesday
but if front were to have a stronger push, then think temps could
be even lower than the low to mid 60s now forecast. Higher
confidence for thunderstorm development on Wednesday now with a
frontal boundary anticipated to in be in place across the CWA.
Large scale ascent appears to be present for most of the day with
rather energetic flow aloft and have maintained likely pops for
the day, but possible ongoing thunderstorms in the morning is
providing lower confidence for thunderstorm intensity later in the
day. With dewpoints likely pooling along boundary, any location
south of the boundary that sees clearing will see instability ramp
up. So despite lower confidence, will need to continue to monitor
for additional chances for at least strong thunderstorms on
Wednesday. No real significant changes to remainder of the
forecast into late in the work week and weekend with mild/moist
conditions and energetic mid levels supportive of continued
chances of thunderstorms.

Rodriguez

&&

.AVIATION...
FOR THE 06Z TAFS...

1210 am...Only concern this period will be wind directions and
possible lake breeze this afternoon. Light southeasterly winds
will turn more southerly around/shortly after sunrise. Directions
will then turn back to the south/southeast or southeasterly at the
Chicago area terminals by afternoon. A lake breeze will likely
develop...but confidence is low regarding how far inland it will
move...including at gyy where winds may become more easterly or
northeasterly in the afternoon. Speeds will likely remain in the
10-12 kt range this afternoon. Winds will then turn back
southerly after sunset with speeds diminishing under 10kts. cms

&&

.MARINE...

110 am...High pressure centered over the eastern lakes this
morning will move southeast to the Carolinas Tuesday morning. The
gradient will tighten this afternoon into tonight ahead of cold
front with southerly winds increasing to 15 to 25 kt. Speeds will
begin to diminish Tuesday afternoon with the cold front moving
across northern parts of Lake Michigan Tuesday evening and then
moving to the southern part of Lake Michigan by Wednesday morning.
Winds will shift northerly behind the front but the gradient is
not particularly strong so not expecting more then 10-20 kt...at
most. As low pressure moves across the northern plains Wednesday
night into Thursday...this frontal boundary will lift back north
across the lake as a warm front with southerly winds then expected
into this weekend. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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