Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 030157
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
857 PM CDT SAT MAY 2 2015

.UPDATE...
ISSUED AT 857 PM CDT SAT MAY 2 2015

ISOLATED TO SCATTERED SHOWERS ARE MOVING INTO THE AREA FROM THE
WEST AND IT APPEARS THEY WILL CONTINUE TO MOVE EAST THROUGH THE
NIGHT. MODELS CONTINUE TO SHOW THIS AREA WEAKENING AS IT MOVES
EAST, AND IR SATELLITE LOOP SEEMS TO SUPPORT THIS WITH CLOUD TOPS
WARMING ACROSS THE WHOLE AREA OF WHERE THE SHOWERS ARE. ITS ALSO
MOVING AWAY INTO A DRIER AIRMASS. HAVE TRIED TO MAKE SOME
ADJUSTMENTS TO POPS FOR REMAINDER OF THE NIGHT IN THE GRIDS. OTHER
PARAMETERS SHOULD BE OK OR RELATIVELY CLOSE TO CURRENT AND
EXPECTED CONDITIONS REMAINDER OF THE NIGHT.

OTHER SHOWERS AND THUNDERSTORMS HAVE BEEN DEVELOPING FURTHER WEST
IN THE PLAINS. HRRR MODEL SHOWS THESE MAKING THEIR WAY INT WESTERN
AND NORTHWESTERN IL TOMORROW MORNING. WILL BE TAKING A CLOSER LOOK
AT THIS OVER THE NEXT SEVERAL HOURS. ANOTHER UPDATE MAY BE NEEDED
LATER THIS EVENING BEFORE NEW FORECAST PACKAGE COMES OUT AT 4AM.

UPDATE TO FORECAST WILL BE COMING SHORTLY.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 255 PM CDT SAT MAY 2 2015

A WEAK SHORT WAVE OVER WESTERN IA WILL TRACK EAST TO THE IL/IA
BORDER BY MIDNIGHT AND WEAKEN AS IT MOVES ACROSS CENTRAL AND
NORTHERN IL OVERNIGHT. AN AREA OF SHOWERS AND ISOLATED THUNDERSTORMS
OVER NORTHERN MO AND SOUTHERN IA WILL CONTINUE TO TRACK EASTWARD
INTO WEST CENTRAL IL EARLY THIS EVENING BETWEEN 6-8 PM AND INTO
CENTRAL IL LATER THIS EVENING AND OVERNIGHT AS SHOWERS BECOME MORE
ISOLATED. HAVE 20-30% CHANCE OF SHOWERS AND ISOLATED THUNDERSTORMS
FROM I-55 NW AFTER SUNSET TONIGHT AND LINGERING ISOLATED LIGHT
SHOWERS UNTIL MID SUNDAY MORNING NORTH OF I-72 UNTIL WEAKENING SHORT
WAVE PASSES EAST OF IL INTO WESTERN IN BY MIDDAY SUNDAY. MID AND
HIGH CLOUDS WILL CONTINUE TO INCREASE FROM THE WEST LATE THIS
AFTERNOON AND EVENING WITH SOUTHEAST IL SEEING LESS CLOUD COVER
TONIGHT SINCE CLOSER TO HIGH PRESSURE RIDGE OVER SOUTHEAST STATES.
LOWS TONIGHT IN THE LOW TO MID 50S WITH COOLEST READINGS NEAR WABASH
RIVER WHERE LIGHTER WINDS AND LESS CLOUD COVER TONIGHT. SSW WINDS
7- 14 MPH AND GUSTS 15-20 MPH THIS AFTERNOON TO DIMINISH LESS THAN
10 MPH AFTER SUNSET AND VEER SSE.

.LONG TERM...(SUNDAY THROUGH SATURDAY)
ISSUED AT 255 PM CDT SAT MAY 2 2015

IOWA SHORTWAVE FORECAST BY MODELS TO TRACK ACROSS THE AREA OVERNIGHT
AND INTO THE MORNING HOURS OF SUNDAY BRINGING ISOLATED SHOWERS TO
PARTS OF THE FORECAST AREA. SOUNDINGS STILL SHOWING A VERY DRY
PROFILE BELOW 725 MB (~8500 FEET) INTO SUNDAY MORNING BEFORE THE
WAVE SHIFTS OFF TO OUR EAST DURING THE MORNING. WILL KEEP SLIGHTS
GOING FOR A FEW HOURS IN THE MORNING BEFORE THE WAVE MOVES OUT OF
THE AREA.

OUR ATTENTION THEN TURNS TO A NORTHERN STREAM SHORTWAVE THAT WILL
DRAG A COLD FRONT SOUTHEAST INTO THE LOWER GREAT LAKES LATE SUNDAY
AND INTO MONDAY INCREASING THE CHANCES FOR MORE WIDESPREAD SHOWERS
AND STORMS...ESPECIALLY OVER THE NORTHERN HALF OF THE FORECAST AREA
WHERE THE BOUNDARY IS FORECAST TO BECOME STATIONARY. AFTER OUR SLIGHT
CHANCES SUNDAY MORNING...THE REST OF THE DAY LOOKS QUIET AND WARM
WITH A GUSTY SOUTH TO SOUTHWEST WIND HELPING TO PUSH AFTERNOON TEMPS
INTO THE UPPER 70S TO LOWER 80S. POPS START TO RAMP UP SUNDAY NIGHT
ACROSS THE FAR NORTHWEST AS THE BOUNDARY EDGES SLOWLY SOUTHEAST WITH
MODELS TRENDING SLOWER WITH THE FRONTAL BOUNDARY AND QPF ALONG IT.
MAY HAVE TO SLOW THE ONSET OF THE SHOWERS EVEN MORE IF THESE TRENDS
CONTINUE. BETTER LOW LEVEL JET SUPPORT AND 850 MB THETA-E ADVECTION
REMAINS OUT TO OUR NORTHWEST LATE SUNDAY NIGHT WITH MOST MODELS
SUGGESTING THAT A CLUSTER OF STORMS...AT LEAST WHAT`S LEFT OF
THEM...WILL APPROACH OUR FAR NORTHWEST COUNTIES WELL AFTER
MIDNIGHT SUNDAY NIGHT.

THE SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TO SPREAD SLOWLY
SOUTHEAST ON MONDAY AND INTO MONDAY NIGHT WITH THE HIGHER THREAT
BEING AGAIN WHERE THE BOUNDARY IS EXPECTED TO BECOME STATIONARY...
WHICH AT THIS TIME LOOKS TO BE NORTH OF I-72. FORECAST SOUNDINGS
SHOWING MIXED LAYER CAPES OF AROUND 1500 J/KG MONDAY AFTERNOON INTO
EARLY MONDAY EVENING WITH THE STRONGER 500 MB WIND FLOW TO OUR NORTH
WITH 30-35 KTS FORECAST. SPC HAS A LARGE AREA OF MARGINAL RISK FOR
SEVERE STORMS MONDAY AFTERNOON AND EVENING STRETCHING FROM THE
SOUTHERN PLAINS UP ACROSS THE NORTHERN HALF OF OUR CWA. SEVERE
PARAMETERS BORDERLINE AT THIS TIME BUT WITH THE BOUNDARY IN THE AREA
AND FORECAST CONVECTIVE TEMPS AROUND 80...MULTI-CELL STORMS SHOULD
DEVELOP DURING THE AFTERNOON AND CONTINUE INTO THE EVENING WITH THE
POSSIBILITY FOR SOME GUSTY WINDS...HAIL AND HEAVY RAINFALL WITH SOME
OF THE MORE ORGANIZED CLUSTERS OF STORMS THAT FORM ALONG THE STALLED
FRONTAL BOUNDARY.

MODELS SUGGEST THE BOUNDARY WILL SHIFT NORTH OF THE AREA STARTING ON
TUESDAY AS UPPER LEVEL HEIGHTS BUILD IN RESPONSE TO A RATHER
VIGOROUS UPPER WAVE THAT WILL BE PUSHING ACROSS THE SOUTHERN ROCKIES
AND EVENTUALLY SWING NORTHEAST INTO THE PLAINS BY MID TO LATE IN THE
UPCOMING WORK WEEK. WILL INDICATE A BIT OF A LULL IN THE SHOWER AND
STORM CHANCES UNTIL LATE THURSDAY OR FRIDAY WHEN THE WAVE WILL
APPROACH OUR AREA. TEMPERATURES LOOK TO BE ABOVE NORMAL THRU THE
WORK WEEK WITH AFTERNOON HIGHS CLIMBING INTO THE UPPER 70S TO LOWER
80S...WHILE EARLY MORNING LOWS ONLY DROP OFF INTO THE UPPER 50S TO
LOWER 60S TUESDAY MORNING...WITH MOST OF OUR AREA SEEING LOW
TEMPERATURES IN THE LOW TO MID 60S FOR THE REMAINDER OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 614 PM CDT SAT MAY 2 2015

HIGH CLOUDS HAVE OVERSPREAD THE TAF SITES THIS EVENING AND AM
EXPECTING MID CLOUDS TO ADVECT INTO THE AREA AS A WEAK WAVE MOVES
INTO THE AREA FROM THE WEST. SHOWERS IS ASSOCIATED WITH THIS WAVE
IN NORTHEASTERN MO AND WEST CENTRAL ILLINOIS. HRRR AND OTHER SHORT
TERM MODELS SHOW THESE LIGHT SHOWERS DISSIPATING AS THEY MOVE EAST
INTO DRIER AIRMASS OVER ILLINOIS. SO WILL BRING IN LOWER CLOUDS
AROUND 8KFT THIS EVENING WITH VCSH. HRRR INDICATES THE SCATTERED
SHOWERS COULD LAST UNTIL MORNING, SO WILL KEEP VCSH UNTIL THEN.
THEN SKY COVER BECOMES SCATTERED MID CLOUDS OR CLEAR FOR
TOMORROW. SOUTHWEST WINDS WILL BECOME SOUTHERLY AS THE WEAK WAVE
MOVES INTO THE AREA AND CONTINUE DURING THE OVERNIGHT HOURS.
SOUTH-SOUTHWEST WINDS WILL BE ON THE BACK SIDE OF THE WAVE
TOMORROW AND PRESSURE GRADIENT WILL TIGHTEN SOME, SO EXPECTING
SOME GUSTS OF 22-25KTS DURING THE LATE MORNING AND INTO THE
AFTERNOON.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...AUTEN
SHORT TERM...07
LONG TERM...SMITH
AVIATION...AUTEN


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