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000
FXUS63 KDVN 250937
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
337 AM CST SUN JAN 25 2015

.SYNOPSIS...
ISSUED AT 336 AM CST SUN JAN 25 2015

LATEST SFC ANALYSIS WAS INDICATING MAIN SFC LOW LOCATED JUST
SOUTHEAST OF THE DSM AREA...WITH PRESSURE FALLS AND TEMP GRADIENT
SUGGESTING IT TO CONTINUE TO PROPAGATE SOUTHEASTWARD INTO EXTREME
NORTHEASTERN MO BY AROUND 12Z THIS MORNING. THE SFC BOUNDARY THE
LOW IS FOLLOWING CURRENTLY DRAPED FROM NEAR SIGOURNEY IA...INTO WEST
CENTRAL IL. TEMPS IN THE UPPER 30S TO STILL AROUND 40 SOUTH OF IT...
AND LOW TO MID 30S NORTH OF IT WITH NORTHEASTERLY BL FLOW STARTING
TO ORGANIZE ACRS NW IL INTO NORTHEASTERN/EAST CENTRAL IA ATTM.
MAINLY LIGHT RAIN SPREADING EASTWARD ACRS THE WESTERN AND SOUTHERN
HALF OF THE DVN CWA AS WELL CURRENTLY. ALOFT...WATER VAPOR IMAGERY
INDICATING MAIN UPPER LOW NEAR SIOUX FALLS SD...WITH EXTRAPOLATION
OF IT/S PATHWAY TAKING IT TO THE EASTERN IA/MO BORDER REGION BY
SUNRISE. A FURTHER SOUTHWESTWARD DIGGING SYSTEM YET THAN MOST MODEL
SOLUTIONS SUGGESTED IT WOULD TRAVEL OVER THE PAST FEW DAYS OF MODEL
RUNS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 336 AM CST SUN JAN 25 2015

TODAY...BULK OF MESOSCALE SOLUTIONS AS WELL AS SYNOPTIC PROGS
CONTINUE TO DIG THE CLIPPER OUT OF NE MO THIS MORNING AND INTO
SOUTHERN IL BY EARLY AFTERNOON. ASSESSING LATEST ELEVATED
FRONTOGENETIC FORCING BANDS WITH THIS PATH...H7-H5 MB WAVE PATH...
CONVERGENT FLOW IN THE H925-H875 MB LAYER SUGGEST A CONTINUED
COMPRESSION OF UPSTREAM PRECIP BANDS INTO A MAIN DEF ZONE ACRS THE
NORTHWESTERN THIRD OF THE CWA FROM WEST OF CEDAR RAPIDS TO JUST
SOUTHWEST OF THE QUAD CITIES FROM 10Z-13Z OR SO THIS MORNING...THEN
SHIFTING SOUTH AND EAST GENERALLY ALONG AND 40-50 MILES SOUTH OF I80
THROUGH 15Z-16Z THIS MORNING. LOOKING AT THERMAL PROFILES AND
RELATIVELY WARM SFC LAYERS...PROBLEM WILL BE THAT MUCH OF THIS LIFT
CONTINUING TO WRING OUT RAIN OR RAIN-SNOW MIX WITH LITTLE SNOW ACCUM
ESPECIALLY WELL SOUTH OF I80 AS THE MORNING PROGRESSES. RAIN OR RAIN-
SNOW MIX TOP-DOWN COOLING INTO SNOW PROFILES AFTER 12Z-14Z NORTH OF
I80...AND NOT TO HWY 34 AND SOUTH TIL AFTER 15Z THIS MORNING. WARM
SFC TEMPS AND LATE TURNOVER DURING MID MORNING WILL LIMIT SNOW ACCUMS
TO A HALF INCH OR LESS OR JUST WET PAVEMENT/GROUND FROM FAIRFIELD IA
TO MONMOUTH IL AND SOUTHWARD. INCREASING/DEEPENING NORTHEASTERLY FLOW
WITH SOME DRIER FETCH...AS WELL AS THE SYSTEM/S FURTHER SOUTHWEST JOG
IN PROPAGATION SHOULD LIMIT THE NORTHEASTERN QUARTER TO EVEN THIRD OF
THE DVN CWA/DBQ EASTWARD TO NORTHEAST OF STERLING IL/ TO NOT MUCH
SNOW ACCUM AS WELL...TRACE TO HALF INCH. FOR AREAS THAT DO GET SOME
WET SNOW ACCUMS FROM 12Z-18Z...LATEST THINKING TAKING INTO ALL THE
PARAMETERS ABOVE INTO ACCOUNT...SUGGEST AN INCH TO 1.5 INCHES ALONG
AND 25 MILES EITHER SIDE OF AN AXIS FROM MARENGO IA...TO CID...
SOUTHEASTWARD THRU THE QUAD CITIES...AND TO PRINCETON IL. BANDED
NATURE OF THE EVENT COULD HAVE A LOCALIZED NARROW SWATH IN THIS
GENERAL AREA OF SOME AREAS OF 2-3 INCHES OF SO. ALL PRECIP CHANGING
TO SNOW IN THE SOUTHEASTERN CWA MIDDAY INTO EARLY THIS AFTERNOON
WITH MINOR ACCUMS BEFORE EXITING THE CWA TO THE SOUTHEAST BY MID
AFTERNOON. INTENSIFYING PRESSURE GRADIENT TO REALLY BOOST
NORTHEASTERLY SFC WINDS TO 15-30 MPH AND HIGHER GUSTS TODAY AND MAKE
FOR SOME LIMITED DRIFTING IN AREAS THAT CAN GET 1-2 INCHES...LIMITED
BECAUSE SNOW WILL BE WET IN NATURE AND COMPACTING. HIGHS DURING THE
MORNING WITH FALLING TEMPS AS THE DAY PROGRESSES.

TONIGHT...NORTHEASTERLY COLD AIR ADVECTION...SOME TEMPORARY SKY
CLEARING...WINDS DROPPING OFF WITH PASSING SFC RIDGE LOBE TO MAKE
FOR A MUCH COOLER NIGHT TONIGHT ESPECIALLY IN AREAS WITH FRESH SNOW
COVER. LOWS WELL DOWN IN THE TEENS IN THE NORTH AND NORTHEAST...TO
AROUND 20 IN THE SOUTH.    ..12..


.LONG TERM...(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 336 AM CST SUN JAN 25 2015

ANOTHER RATHER BENIGN MILD WEEK IS ON THE WAY FOR THE MIDWEST...AS
THE PRIMARY CLIPPER TRACK REMAINS NORTH OF IOWA. THIS PLACES OUR CWA
IN GLANCING BLOWS OF BOTH WAA LIGHT SNOW EVENTS...AND ON THE EDGE OF
THE COLD AIR QUICKLY FOLLOWING BEHIND SEVERAL CLIPPERS THROUGH THE
WEEK. THE MODEL BLEND KEEPS POPS VERY LOW APPROPRIATELY FOR THESE
EVENTS...AS THE MAIN SYNOPTIC CONVERGENCE...AND LIKELY DEEP
SATURATION SHOULD BE WELL NORTH OF OUR CWA.

MONDAY WILL SEE WAA THROUGH THE DAY...AND THIS SHOULD RESULT IN
CLOUDS...ESPECIALLY NORTH AND EAST. THE ECMWF CONTINUES TO SHOW SOME
LIGHT QPF...BUT WITH SATURATION GREATLY IN QUESTION FOR THIS FAST
MOVING EVENT...WILL HOLD POPS TO UNDER 30 PERCENT IN THE NORTHEAST
ONLY. TEMPERATURES MONDAY SHOULD RESPOND DUE TO THE LACK OF
WIDESPREAD SNOW COVER...AND I HAVE CHOSEN NOT TO GO BELOW GUIDANCE
AS I NORMALLY WOULD FOLLOWING A SNOW EVENT. IN THE END...AFTER
TODAYS MILD START...AND WET SNOW...I JUST AM NOT SURE THAT REMAINING
SNOW COVER WILL SURVIVE THE WAA MONDAY MORNING ENOUGH TO HOLD
TEMPERATURES DOWN UNDER GUIDANCE.

EITHER WAY MONDAYS TEMPERATURES GO...THERE WILL NOT BE SNOW AROUND
FOR TUESDAY. TUESDAY THROUGH WEDNESDAY WILL SEE MORE SIGNIFICANT
WAA...AHEAD OF A SYSTEM THAT IS GAIN PARTIALLY PHASED WITH ENERGY
OVER-TOPPING THE WESTERN UPPER RIDGE...AND ENERGY COMING SOUTHEAST
FROM SOUTHERN CANADA. THIS PARTIAL PHASING IS EXPECTED TO CREATE
BROAD LOW PRESSURE IN THE PLAINS TUESDAY...AND A SURFACE LOW THROUGH
IOWA WEDNESDAY. WHILE THE DETAILS OF THIS MAY CHANGE SOME DUE TO THE
COMPLICATED NATURE OF THIS PHASING INTERACTION...IT IS GOOD BET THAT
48 HOURS OF WAA WILL BRING OUR TEMPERATURES WELL ABOVE NORMAL...MUCH
LIKE YESTERDAY. AFTER HIGHS IN THE MID 30S NORTHEAST TO LOWER 40S
SOUTHWEST TUESDAY...WEDNESDAY SHOULD SEE THE WARMEST HIGHS OF THE
WEEK WITH LOWER 40S NORTH TO LOWER 50S SOUTH.

MODELS ARE GREATLY VARIED ON UPPER SUPPORT FOR RAIN/SNOW WEDNESDAY
NIGHT INTO THURSDAY. OUR POPS ARE VERY LOW...BUT THE SYSTEM COULD BE
WORTH ADDING MORE POTENTIAL FOR SNOW IF THE ECMWF IS CORRECT IN
SIGNIFICANT SYSTEM PHASING THIS FAR WEST. OTHERWISE...OUR FORECAST
REMAINS DRY.  LOOKING TO NEXT WEEKEND...THE GFS KEEPS THE CLIPPER
TRACK AND COLD AIR DISPLACED WELL TO THE NORTH OF IOWA...WHILE THE
ECMWF HAS A STRONG COLD FRONT WITH A 1050MB SFC HIGH BUILDING IN FOR
SATURDAY NIGHT.  CERTAINLY CONFIDENCE ON THAT TRANSITION IS
LOW...BUT IT SHOULD BE NOTED THAT BOTH THE GFS AND ECMWF ONLY OFFER
A VERY BRIEF SHOT OF COLD AIR BEFORE MILD AIR SPREADS BACK OVER THE
MIDWEST. FOR NOW...IT LOOKS LIKE OUR TRANSITION TO FEBRUARY WILL BE
A CONTINUATION OF THE PAST MILD WEEK.
ERVIN

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1143 PM CST SAT JAN 24 2015

VFR CONDITIONS TO START THE OVERNIGHT WITH BKN-OVC CLOUDS WITH CIGS
AOA 6KFT AGL ALONG WITH SPRINKLES AND SCATTERED LIGHT RAIN WEST OF
THE MISSISSIPPI RIVER. CONDITIONS WILL DETERIORATE TO MVFR/IFR
LATE TONIGHT AND SUNDAY AM WITH ANY LIGHT RAIN CHANGING TO SNOW
(ROUGHLY 25/10Z-25/16Z FROM N TO S)... WITH PERIOD OF LIGHT TO
POSSIBLY MODERATE SNOW BEFORE ENDING LATE AM THROUGH EARLY AFTN AS
CLIPPER SYSTEM DEPARTS. WINDS WILL CONTINUE BACKING TO E/NE
THROUGH DAYBREAK THEN INCREASE FROM NORTHEAST SUNDAY AT 10-20 KTS.
CONDITIONS SHOULD BEGIN IMPROVING TO VFR BY MID TO LATE SUNDAY
AFTN WITH VFR CONDITIONS SUNDAY NIGHT AND N/NE WINDS AROUND 10KTS.

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...ERVIN
AVIATION...05