Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1106 PM CDT MON JUL 6 2015

.UPDATE...
ISSUED AT 905 PM CDT MON JUL 6 2015

BAND OF SHOWERS AND THUNDERSTORMS CONTINUES TO SLOWLY PUSH EAST
AND SOUTHEAST INTO PORTIONS OF WEST CENTRAL IL THIS EVENING. THE
INTENSITY HAS DROPPED OFF CONSIDERABLY DESPITE THE FACT THE
OBJECTIVE ANALYSIS INDICATES MIXED LAYER CAPES OF 1500-2000 J/KG.
HOWEVER...WITH THE LOSS OF DAYTIME HEATING AND SOME RATHER STOUT
LOW LEVEL LAPSE RATES...THE COMBINATION OF VERY WEAK SHEAR ALOFT
AND POOR MID LEVEL LAPSE RATES HAS LED TO AN OVERALL DECREASE IN
INTENSITY. THESE STORMS ARE STILL VERY CAPABLE OF PRODUCING
TORRENTIAL RAINFALL IN A SHORT PERIOD OF TIME WITH PRECIPITABLE
WATER VALUES OF OVER 2 INCHES ACROSS THE ILLINOIS RIVER VALLEY.
THE STORMS WILL CONTINUE TO MAKE SLOW PROGRESS EAST AND SOUTHEAST
OVERNIGHT AS THE COLD FRONT EDGES INTO OUR NORTHWEST COUNTIES
TOWARDS MORNING. CURRENT FORECAST HAS THE EVENING AND OVERNIGHT
TRENDS WELL IN HAND...AS A RESULT...MAKING ONLY MINOR ADJUSTMENTS
TO THE PRECIPITATION WORDING FOR THE OVERNIGHT HOURS. NO ZFP
UPDATE NEEDED AT THIS TIME. 

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 307 PM CDT MON JUL 6 2015

ISOLATED SHOWERS AND THUNDERSTORMS WERE DEVELOPING DURING PAST HOUR 
ALONG OUTFLOW BOUNDARY EAST OF THE IL RIVER FROM MCS OVER IA FROM 
NORTH OF LINCOLN TO EAST OF OTTAWA. HAVE STRONGER CONVECTION WITH 
HEAVY RAINS AROUND ST LOUIS METRO WHILE MORE WIDESPREAD 
SHOWERS/THUNDERSTORMS OVER IA...WI...NORTHERN IL AND NW MO. THIS 
CONVECTION IN A VERY UNSTABLE AIRMASS WITH CAPES 2-4 J/KG OVER 
CENTRAL/SE IL (3-4K J/KG WEST OF I-57 AT 19Z). BULK SHEAR IS WEAK 20 
KTS OR LESS OVER CWA SO ORGANIZED SEVERE WX . COLD FRONT WAS 
EXTENDING FROM 1007 MB SURFACE LOW PRESSURE OVER NW WI WITH COLD 
FRONT EXTENDING SW THRU CENTRAL IA/KS. ISOLATED TO SCATTERED SHOWERS 
AND THUNDERSTORMS TO CONTINUE TO DEVELOP DURING REST OF THIS 
AFTERNOON AND EARLY EVENING ESPECIALLY FROM I-57 WEST. COLD FRONT TO 
PUSH SE TOWARD I-55 BY 12Z/TUE WITH INCREASING CHANCES OF SHOWERS 
AND THUNDERSTORMS FROM NW TO SE DURING THE EVENING OVER CENTRAL IL 
AND INTO SOUTHEAST IL LATER TONIGHT INTO TUE. SPC HAS SLIGHT RISK OF 
SEVERE STORMS NW OF I-55 LATE THIS AFTERNOON AND EVENING FOR 
DAMAGING WIND GUSTS ALONG WITH HAIL. HEAVY RAINS AND FREQUENT 
LIGHTNING MAY ALSO OCCUR WITH SOME OF THESE THUNDERSTORMS. LOWS 
TONIGHT RANGE FROM MID 60S NW OF THE IL RIVER TO THE LOWER 70S SE OF 
I-55 WHICH STAYS IN WARM SECTOR THROUGH TONIGHT.

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 307 PM CDT MON JUL 6 2015

FRONT THAT IS MOVING INTO THE AREA TONIGHT WILL BE SITTING OVER 
SOUTHEASTERN PART OF THE STATE TUESDAY. THIS WILL BE THE FOCUS FOR 
MORE THUNDERSTORMS FOR TUESDAY AND TUESDAY NIGHT...THAT SHOULD 
EFFECT MOSTLY THE SOUTHERN HALF OF THE STATE...OR THE SOUTHERN PART 
OF THE CWA. THEN MODELS ARE SIMILAR IN FORECASTING ANOTHER WAVE 
LIFTING OUT OF THE SOUTHERN PLAINS ALONG THE FRONT AND ACROSS 
CENTRAL ILLINOIS WED THROUGH WED NIGHT...AND THEN MOVING EAST OF THE 
AREA EARLY THURSDAY. THUNDERSTORMS WITH MODERATE RAIN CAN BE 
EXPECTED TOMORROW AND TOMORROW NIGHT...BUT THEN HEAVY RAINFALL WILL 
BE POSSIBLE WHEN THE SFC LOW PRESSURE AREA MOVES ACROSS THE AREA FOR 
WED AND WED NIGHT. FLASH FLOOD WATCH MAY BE NECESSARY FOR THIS TIME 
PERIOD BUT THINK ANOTHER LOOK TONIGHT AND/OR TOMORROW IS 
WARRANTED...AFTER SEEING WHAT THE CONVECTION DOES WITH THE 
FRONT/OUFLOW BOUNDARY TOMORROW AND TOMORROW NIGHT. 

UNFORTUNATELY THE BOUNDARY REMAINS AROUND OR NEAR THE AREA THE
REST OF THE WEEK...WHICH WILL KEEP A CHANCE OR LIKELY PCPN IN THE
AREA THROUGH FRI NIGHT. THE FRONT SHOULD BE LIFTING FRI NIGHT AS
WELL...WHICH WILL PUSH THE CHANCE OF PCPN NORTH OF THE I-74 FRIDAY
NIGHT THROUGH SUNDAY. THEN MODELS BRING ANOTHER WEATHER SYSTEM
ACROSS ILLINOIS WITH MORE PCPN FOR SUNDAY NIGHT AND MONDAY.

AFTER THIS FRONT MOVES THROUGH THE AREA...TEMPS WILL COOL A LITTLE. 
BUT THEN THEY WILL WARM AGAIN FOR THE WEEKEND AND INTO NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1100 PM CDT MON JUL 6 2015

BAND OF SHOWERS AND ISOLATED THUNDERSTORMS CONTINUES TO MARCH
SLOWLY EAST AND SOUTHEAST LATE THIS EVENING AND WILL CONTINUE
TO DO SO INTO THE EARLY MORNING HOURS. A COLD FRONT OUT TO OUR
WEST WILL PUSH ACROSS THE ILLINOIS RIVER VALLEY BETWEEN 07Z AND
10Z...THE I-55 CORRIDOR BETWEEN 10Z-14Z AND POINTS FURTHER EAST
IN THE 14Z-18Z TIME FRAME. IT IS RIGHT ALONG AND BEHIND THE COLD
FRONT WHERE WE SEE CIGS DROP TO MVFR WITH SOME AREAS OF IFR CIGS
POSSIBLE TUESDAY MORNING. SOMEWHAT DRIER AIR WILL ADVECT SOUTH
INTO NORTH CENTRAL IL TUESDAY AFTERNOON AND WE SHOULD SEE CIGS
IMPROVE TO VFR AFTR 19Z...WITH THE MVFR CIGS HOLDING FURTHER
SOUTH UNTIL EVENING. SURFACE WINDS WILL GRADUALLY VEER INTO THE
SOUTHWEST AND WEST AT 8 TO 13 KTS OVERNIGHT AND INTO THE NORTHEAST
AT 10 TO 15 KTS AFTR FROPA TOMORROW MORNING AND HOLD FROM A
NORTHEAST DIRECTION INTO THE EVENING.

&&

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

$$

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

National Weather Service Glossary of Abbreviations