Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 231750
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1150 AM CST TUE DEC 23 2014

.SYNOPSIS...
ISSUED AT 332 AM CST TUE DEC 23 2014

THE SURFACE AND UPPER LOW ARE LOCATED OVER IOWA EARLY THIS
MORNING...WITH A DRY SLOT STEADILY WORKING NORTHWARD THROUGH THE
CWA. A WARM WEDGE OF AIR IS LOCATED AT THE SURFACE ALONG AN
OCCLUDING FRONTAL BOUNDARY LOCATED ALONG INTERSTATE 80 AS OF 2 AM.
THIS SEPARATES THE COOL RAINS IN THE NORTHERN CWA WITH TEMPERATURES
IN THE MID TO UPPER 30S...FROM THE SOUTH HALF...WHICH IS SLOWLY
RISING THROUGH THE MID 40S. THE NORTH PORTION OF THE CWA IS LIKELY
GOING TO GET INTO THIS MILD AIR BRIEFLY EARLY TODAY BEFORE THE
BOUNDARY SLIPS SOUTH AGAIN.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 332 AM CST TUE DEC 23 2014

FOR NEARLY ALL OF THE CWA...TODAY WILL BE DRY DAY. THE MID LEVEL DRY
AIR SHOULD REMAIN OVER EASTERN IOWA AND ILLINOIS THROUGH THE
DAY...WITH THE SYSTEM LIFTING NORTH INTO WISCONSIN BY LATE
AFTERNOON. THIS SHOULD ALSO KEEP COLD ADVECTION AT BAY...MORE OR LESS
HOLDING THE SEASONAL CONDITIONS IN OUR NORTHWEST IN PLACE...WHILE
ALLOWING THE SOUTHEAST TO REMAIN IN THE 40S THROUGH THE DAY. THE
SOUTH MAY BRIEFLY SEE BREAKS IN THE OVERCAST EARLY TODAY...BUT ALL
MODELS INDICATE THE STRATUS FILLING BACK OVER THE ENTIRE AREA BY MID
DAY. UNDER THE CLOUDS...HEATING SHOULD NOT REALLY OCCUR...BUT A
GRADUAL DIURNAL INCREASE IN CEILING HEIGHT IN THE SOUTHEAST 1/2
SHOULD ALLOW FOR TEMPERATURES TO PEAK MID DAY IN THE UPPER
40S...WHICH IS ONLY ABOUT 2 T 3 DEGREES WARMER THAN THE 2 AM
TEMPERATURES. THUS FAR...THE DRY SLOT HAS NOT HAD ANY NOTABLE
DRIZZLE...AND WHILE POSSIBLE...WILL KEEP THIS WORDING OUT TODAY
UNTIL I SEE SOME DEVELOP SINCE THE FORCING IS ALREADY IN PLACE RIGHT
NOW. FOG THUS FAR WAS CONFINED TO THE PERIOD YESTERDAY AFTERNOON AND
EVENING BETWEEN THE TWO ROUNDS OF RAINFALL. LITTLE ADDITIONAL FOG
HAS DEVELOPED ALONG THE BOUNDARY OVERNIGHT...BUT WILL KEEP SOME
MENTION IN OUR NORTHWEST TODAY WHERE IT WOULD STILL BE MOST LIKELY
TO DEVELOP. WITH A CONVERGENT BOUNDARY OVER COOL GROUND AND
DEWPOINTS NEAR 40...THE POTENTIAL IS STILL THERE WHEN THE RAIN EXITS
IN THE NEXT FEW HOURS.

TONIGHT...THE PUSH OF COLD AIR SHOULD NOT GET GOING TO WELL AFTER
MIDNIGHT...THUS...WHILE ONLY A SLIGHT CHANCE OF PCPN IS EXPECTED
WEST...IT SHOULD STILL BE MIXED IN NATURE AND VERY VERY LIGHT. THE
NEXT SYSTEM EXPECTED TO MOVE TO THE EAST OF THE CWA WEDNESDAY SHOULD
NOT IMPACT OUR AREAS TONIGHT...AS ANY WRAP AROUND MOISTURE PROCESSES
SHOULD NOT BE ESTABLISHED THROUGH 6 AM. IN OUR BORDER AREAS TO THE
EAST...AND WEST...WHICH ARE CLOSER TO DEEPER SATURATION...I HAVE
ELECTED TO INCLUDE SLIGHT CHANCES FOR RAIN/SNOW MIX LATE TONIGHT.
ERVIN

.LONG TERM...(WEDNESDAY THROUGH NEXT MONDAY)
ISSUED AT 332 AM CST TUE DEC 23 2014

WEDNESDAY AND THURSDAY...MAIN FCST CHALLENGE THIS PERIOD CONTINUES TO
BE THE POTENTIAL CHRISTMAS EVE DAY STORM ALONG AND EAST OF THE
DVN CWA...AS WELL AS PLENTY OF MODEL INCONSISTENCY/VARIANCES
BETWEEN THE SOLUTIONS AND RUNS. ASSESSING THE VARIOUS 12Z MODEL
RUNS AND LOOKING AT 00Z UPPER AIR ANALYSIS WITH EXTENT OF UPPER
WAVE/JET ENERGY DUMPING DOWN THE WEST SIDE OF THE MID CONUS L/W
TROF...FEEL THE 00Z RUN ECMWF AND THE EASTWARD ADJUSTMENT OF BOTH
SFC AND UPPER LOW PROPAGATION ON WED PROBABLY MORE CORRECT. THE
RECENT 06Z NAM WHICH SIDES WITH THE LATEST EURO OR EVEN A BIT SLOWER
AN FURTHER EAST MAY BE LATCHING ON TO SYNOPTIC ENERGY SAMPLING AND
HAS EVEN MORE OF A HANDLE OR AT LEAST A CORRECT TRENDING. THE GFS
AGAIN SEEMS TOO BULLISH ON IT/S WESTWARD GYRATION INTO WED EVENING
WHICH WOULD PRODUCE 2-3+ INCHES OF SNOW ACRS MUCH OF BUREAU AND
PUTNAM COUNTIES. THE LATEST NAM/ECMWF GENERALLY SUGGEST AROUND A 998
MB SFC LOW IN THE VCNTY OR NORTH OF NASHVILLE TN AT 12Z WED...
DEEPENING TO 992 MB ACRS SOUTHEASTERN IND BY 18Z...THEN OFF TO
NORTHWESTERN OH OR EXTREME SOUTHEASTERN LOWER MI AT AROUND 988/987 MB
OR SO. H85 TO H7 MB LOW PROGRESSION UTILIZING THESE SOLUTIONS SUGGEST
DEF ZONE PRECIP BAND TO ROLL UP WELL TO THE EAST OF THE DVN CWA WED
INTO WED EVENING...WITH MAYBE JUST SOME LIGHT PRECIP IN THE FAR
EASTERN CWA FOR PORTIONS OF THE DAY. BULK OF TH AREA COULD REMAIN
LARGELY DRY. THERMAL PROFILES STILL SUGGEST A RAIN-SNOW MIX IN THE
EASTERN FCST AREA FOR PART OF THE MORNING...TOP-DOWN COOLING TO ALL
SNOW BY AFTERNOON FOR WHATEVER PRECIP CAN MAKE IT THIS FAR WEST.
SFC/BOUNDARY LAYER MOISTURE-SATURATION PROFILES AS WELL AS RECENTLY
WARMED GROUND WILL MAKE FOR ANY SNOW ACCUMULATION TO BE TOUGH TO
DO...MAYBE WET SLUSHY ACCUMULATION OF LESS THAN AN INCH ACRS PUTNAM
AND THE EAST HALF OF BUREAU COUNTIES AND JUST EAST OF FREEPORT IN NW
IL. AGAIN STRESSING THE WET NATURE TO THE SNOW AND MUCH OF IT
MELTING UPON CONTACT WITH THE SFC...HIGH TEMPS IN THE MID OR EVEN
30S. ANY LINGERING PRECIP WILL LOOK TO EXIT THE FAR EASTERN DVN CWA
BY 6-7 PM CST WED EVENING. LOWS WED NIGHT INTO THU MORNING NOT ALL
THAT EXTREME DESPITE POST-STORM IN WRAPPING COOL ADVECTION...LOWS IN
THE MID 20S TO AROUND 30 FOR MOST OF THE CWA. PASS BULGE OF SFC
RIDGING TO ALLOW LLVL RETURN FLOW AND TEMP REBOUND LATER CHRISTMAS
DAY/AFTERNOON...ALONG WITH SOME MUCH NEEDED SUNSHINE FOR HIGHS BACK
INTO THE UPPER 30S TO MID 40S.

FRIDAY THROUGH NEXT MONDAY...THE FRIDAY WAVE EJECTING OUT OF
LINGERING SOUTHWESTERN CONUS TROFFINESS STILL LOOKS ON TRACK BY
BULK OF LATEST MEDIUM RANGE RUNS/ENSEMBLES TO PULL UP OUT OF THE
SOUTHERN PLAINS AND PROPAGATE FROM ACRS SOUTHWESTERN INTO
NORTHEASTERN IA...PLACING THE LOCAL AREA IN THE WARM SECTOR AND
PROBABLY DRY SLOT. THE EURO CONTINUE TO BE THE MOST BULLISH ON MILD
HIGH TEMPS FRI WITH MUCH OF THE CWA IN THE UPPER 40S TO LOWER 50S
AND NOT ALL THAT FAR AWAY/5-8 DEGREES OR SO/ FROM RECORD HIGHS FOR
DEC 26TH FOR SEVERAL CLIMATE SITES. A LOW CHC FOR SOME WRAP AROUND
PRECIP BEHIND PASSING WAVE FRI NIGHT ALONG WITH SOME COLD AIR
ADVECTION THAT MAY MAKE FOR SOME MIXED PRECIP POTENTIAL...BUT FEEL
AGAIN THAT THE ECMWF AN IT/S MAINLY DRY FCST LOCALLY FOR FRI NIGHT
PROBABLY THE WAY TO GO. BAROCLINICITY LAYS OUT IN SOUTH-WESTERLIES
BEHIND THE PASSING FRI NIGHT LOW PRESSURE SYSTEM...FROM THE SOUTHERN
PLAINS TO THE GRT LKS. THE ECMWF DOES EJECT OUT ANOTHER WAVE ALONG
THIS ZONE AND WHILE THE BULK OF THE PRECIP CURRENTLY PROGGED TO
REMAIN TO THE SOUTH OF THE DVN CWA...SOME LIGHT SNOW PRODUCING A
DUSTING TO HALF INCH MAY CLIP THE SOUTHEASTERN THIRD OF THE CWA ON
SAT. SFC RIDGING TO FOLLOW FOR A DRY AND SEASONABLY SUNDAY...THEN
DEEP AND LARGE SCALE L/W TROFFINESS TRIES TO RE-ADJUST FROM THE GRT
BSN TO THE NORTHWESTERN GRT LKS EARLY NEXT WEEK. THERE MAY BE
ANOTHER WX SYSTEM TO EVENTUALLY AFFECT PORTIONS OF THE CWA TOWARD
NEW YEARS...BUT CONFIDENCE AND TIMING LOW AT THIS POINT.    ..12..

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1150 AM CST TUE DEC 23 2014

PERIODS OF IFR FOR CIGS WILL CONTINUE THROUGH THIS AFTN AT KCID
AND KDBQ. THESE TERMINALS ARE ON THE COOLER SIDE OF A EASTWARD
MOVING FRONTAL BOUNDARY. WINDS WILL VEER FROM SW TO NW AFTER 06Z
TONIGHT AND THE STRATUS DECK WILL MOVE EASTWARD THROUGH THE
OVERNIGHT. PRECIP CHANCES ARE LIMITED BUT DID INCLUDE VCSH AT
KMLI/KBRL WED MORNING. CIGS MAY IMPROVE AT KCID AND KDBQ AFTER
15Z/WED AS DRIER AIR WORKS IN BUT REMAIN NEAR IFR AT KMLI/KBRL.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...12
AVIATION...UTTECH





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