FXUS63 KILX 230550
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1150 PM CST TUE DEC 22 2009
.DISCUSSION...
ISSUED 841 PM CST TUE DEC 22 2009
PCPN HAS BEGUN IN SOME AREAS OF CWA THIS EVENING. BASED ON NEW NAM
MODEL RUN...THIS SHOULD CONTINUE AND EXPAND THROUGHOUT THE WHOLE
AREA OVERNIGHT. RADAR TRENDS FOR LSX SEEM TO SUPPORT THIS. TEMPS
ARE REMAINING STEADY INSPITE OF EASTERLY FLOW WILL LOWER DEWPOINTS AND
PCPN BEGINNING. STILL THINK TEMPS WILL FALL ENOUGH FOR SOME AREAS
NORTH OF I-74 TO EXPERIENCE SOME FREEZING DRIZZLE...SO WILL KEEP
IN FORECAST WITH NO CHANGES WITH ADVISORY OVERNIGHT. ALSO...
TEMPS OUTSIDE OF CITIES COULD BE COUPLE OF DEGREES COOLER...SO
FZDZ OR FZRA STILL POSSIBLE OVERNIGHT IN ADVISORY AREA. HAVE
INCREASED POPS FOR NOW TO BEFORE MIDNIGHT SO UPDATE WILL BE FORTHCOMING.
AUTEN
&&
.AVIATION...
ISSUED 1150 PM CST TUE DEC 22 2009
CONDITIONS IFR OR WORSE AT ALL SITES AND EXPECT THAT TO CONTINUE
NEXT 24HRS AT ALL SITES. PIA AND BMI ARE STARTING WITH DZ BUT WILL
CHANGE TO ALL RAIN BY MORNING. EASTERLY WINDS WILL INCREASE
TOMORROW AND THEN DECREASE IN THE EVENING AROUND 00Z.
AUTEN
&&
.PREV DISCUSSION...
ISSUED 210 PM CST TUE DEC 22 2009
SHORT TERM...TONIGHT THROUGH FRIDAY
...LIGHT ICING POSSIBLE NORTH OF INTERSTATE 74 TONIGHT INTO
WEDNESDAY MORNING WITH AN INCREASING FLOOD THREAT OVER CENTRAL
EAST CENTRAL AND SOUTHEAST ILLINOIS LATE WEDNESDAY THROUGH THU
EVENING...
MAJOR WINTER STORM THE MAIN FORECAST ISSUE THIS PERIOD AND ITS
OVERALL AFFECT IN OUR AREA INTO FRIDAY. MODELS IN DECENT AGREEMENT
WITH THE DETAILS OF THE POTENT STORM SYSTEM FORECAST TO SLOWLY
PUSH OUT OF THE SOUTHERN PLAINS LATE TOMORROW INTO XMAS EVE.
PRIMARY CONCERN WL INITIALLY BE WITH SOME LIGHT ICING MAINLY NORTH
OF INTERSTATE 74 TONIGHT INTO WED MRNG...FOLLOWED BY A FLOOD THREAT
STARTING LATE TOMORROW THRU THU EVENING WITH MODELS CONTINUING TO
INDICATE CENTRAL ILLINOIS IN STORE FOR 2 TO 3 INCHES OF RAIN BY
THE TIME THE SYSTEM DRY SLOT PUSHES ACRS THE AREA LATER THU EVENING.
MODEL FORECAST SOUNDINGS LATER THIS EVENING INTO WED MRNG SUGGEST
AREAS NORTH OF A GALESBURG TO PEORIA TO DANVILLE LINE MAY SEE A
PERIOD OF FREEZING DRIZZLE AS SFC TEMPS WL BE AT OR JUST BELOW
FREEZING. DO EXPECT WITH STRONG LOW LEVEL WARM ADVECTION TO CONTINUE
ACRS THE AREA ON WEDNESDAY...THAT SFC TEMPS SHOULD RISE ABOVE
FREEZING IN OUR EXTREME NORTHERN AREAS DURING THE MORNING HOURS.
HOWEVER...INCREASING EASTERLY SURFACE WINDS WILL BE MAKING IT A
STRUGGLE TO SEE MUCH IN THE WAY OF ANY SIGNIFICANT RISE IN TEMPS
UNTIL LATER IN THE MORNING OR DURING THE AFTERNOON. WILL ISSUE A
WINTER WEATHER ADVSY FOR FREEZING DRIZZLE LATER THIS EVENING INTO
WED MRNG FOR THE AREAS MENTIONED ABOVE. 12KM NAM-WRF SOUNDINGS
CONTINUE TO SHOW NOT MUCH MOISTURE ABOVE 800 MB SUGGESTING A THREAT
MORE TWDS DRIZZLE/FREEZING DRIZZLE THRU MOST OF THE NIGHT...WITH
THE DEEPER MOISTURE TRANSPORT NOT EXPECTED UNTIL LATER WEDNESDAY.
STRONG MOISTURE TRANSPORT AND 850 MB THETA-E ADVECTION GETS GOING
TO OUR SOUTH TMRW MRNG AND SHIFTS INTO OUR AREA DURING THE DAY
BRINGING PERIODS OF MODERATE TO LOCALLY HEAVY RAINFALL INTO THU
AFTN AND EVENING. SOME THUNDER POSSIBLE AS WELL ACRS THE SOUTH
HALF OF THE FORECAST AREA WHICH WILL ONLY SERVE TO AGGRAVATE THE
FLOOD POTENTIAL IN OUR AREA. PRECIP WATER VALUES UP TO 1.25 INCHES
TO OUR SOUTH WHICH IS WELL ABOVE NORMAL FOR THIS TIME OF YEAR.
FROST DEPTH OBSERVATIONS ACRS THE AREA INDICATE DEPTHS OF BETWEEN
3 TO 5 INCHES...THUS THE 2 TO 3 INCHES OF RAIN EXPECTED OVER THE
AREA WL ALL GO RUNOFF INTO AREA STREAMS AND RIVERS. INITIAL SFC
WAVE TO SHIFT INTO WRN IOWA BY THU MRNG WITH AN EVEN STRONGER
SURFACE LOW FORECAST TO DEVELOP OVR NRN LOUISIANA AND TRACK
STRAIGHT NWD INTO WRN IL BY THU NIGHT BRINGING ADDITIONAL MODERATE
TO LOCALLY HEAVY RAINS INTO OUR AREA. ISSUING A FLOOD WATCH FOR
ALL OF OUR AREA STARTING AT NOON ON WED AND CONTINUING THRU THU
EVENING WHEN MODELS CONTINUE TO INDICATE THE MID LEVEL DRY SLOT WL
SHUT DOWN THE SIGNIFICANT RAINS IN OUR AREA.
MODELS SLOWING THE TRACK OF THE SFC AND UPPER SYSTEMS ON FRIDAY
RESULTING IN A CONTINUATION OF PRECIP CHANCES DURING XMAS DAY.
STRONG COLD ADVECTION...GUSTY WEST WINDS AND PERIODS OF SNOW
SHOWERS WILL BE THE STORY FOR XMAS DAY WITH FALLING TEMPERATURES.
LONG TERM...SATURDAY THROUGH TUESDAY
AS MENTIONED ABOVE...MODELS ADVERTISING A SLOWER SOLUTION TO THE
DEEP UPPER LOW AND ATTENDANT SFC LOW THIS PERIOD. WITH THE EXPECTED
UPPER LEVEL WAVES PIN-WHEELING AROUND THE LOW AND CONTINUED COLD
ADVECTION OVER AREA...SHOULD HAVE PERIODIC SNOW SHOWERS OVER
REGION FOR FRIDAY NIGHT INTO SUNDAY. HAVE THEREFORE ADDED POPS
FOR CHANCE OF SNOW SHOWERS THROUGH THAT TIME FRAME.
EXPECT THE UPPER LOW TO MOVE OFF BY MONDAY...WITH SOME POSSIBLE
BREAKUP OF CLOUDINESS...BUT STILL RATHER COLD. NEXT POTENTIAL STEM
TO WATCH MAY BE AFFECTS OF THE DEVELOPING LOW ALONG THE GULF...FOR
MID NEXT WEEK.
SMITH (SHORT TERM)/GOETSCH (LONG TERM)
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.
WINTER WEATHER ADVISORY UNTIL NOON CST WEDNESDAY FOR ILZ027>031-
037-038-045-046.
&&
$$
