731
FXUS63 KDVN 181126
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
526 AM CST FRI JAN 18 2019
..12Z AVIATION UPDATE
SYNOPSIS
ISSUED AT 320 AM CST FRI JAN 18 2019
CANADIAN HIGH PRESSURE WAS CENTERED OVER THE UPPER MIDWEST EARLY
THIS MORNING. THE SURFACE RIDGE AXIS IS BUILDING INTO THE AREA
PROVIDING THE PROVERBIAL CALM BEFORE THE STORM, WITH EVEN SOME
DECREASE IN STRATUS NOTED ACROSS PORTIONS OF NORTHEAST AND EAST
CENTRAL IOWA. MEANWHILE, THE UPPER LEVEL SHORTWAVE SET TO BRING
ACCUMULATING SNOW TO THE REGION OVER THE NEXT 24+ HOURS IS
CURRENTLY PROGRESSING THROUGH THE ROCKIES.
SHORT TERM
(TODAY THROUGH SATURDAY)
ISSUED AT 320 AM CST FRI JAN 18 2019
BOTTOM LINE UP FRONT...
HAVE UPGRADED THE REST OF THE WINTER STORM WATCH TO A WINTER STORM
WARNING. DECISION TO UPGRADE WAS BASED LARGELY ON IMPACTS RATHER
THAN CRITERIA WARNING AMOUNTS.
SNOWFALL TIMING... CONFIDENCE IS MODERATE. SEEING A LITTLE SLOWING
OF THE FORCING AND SATURATION. IN GENERAL, STILL EXPECTING SNOW TO
DEVELOP NORTH/WEST OF QUAD CITIES THIS AFTERNOON AND LASTLY INTO
OUR FAR EAST/SOUTHEAST COUNTIES BY EARLY EVENING. SNOW CONTINUES
OVERNIGHT TAPERING OFF FROM NW TO SE LATE TONIGHT THROUGH
MID MORNING SATURDAY.
SNOWFALL AMOUNTS... CONFIDENCE IS MODERATE. ACCUMULATIONS ARE
FORECAST IN THE RANGE OF 4-8 INCHES, WITH THE HIGHER AMOUNTS
LIKELY FOCUSING IN A BAND(S) NORTH/WEST-SOUTHWEST OF THE QC METRO.
WINDS... INCREASING TO 15 TO 25 MPH WITH GUSTS TO 35 MPH, WITH THE
STRONGEST WINDS FAVORING THE SE 2/3RDS OF CWA OVERNIGHT INTO
MUCH OF SATURDAY BEFORE SLOWLY DIMINISHING LATE IN THE DAY INTO
SATURDAY NIGHT.
MAIN IMPACTS...
1) PERIODS OF LOW VISIBILITY AND POSSIBLY NEAR WHITEOUT FOR BRIEF
PERIODS OF TIME IN BLOWING SNOW AND DURING MODERATE TO LOCALLY
HEAVY SNOWFALL RATES.
2) EVOLVING DRIER/FLUFFY NATURE OF SNOW WITH THE BRISK/GUSTY WINDS
MAY LEAD TO CONSIDERABLE DRIFTING OF SNOW HAMPERING REMOVAL EFFORTS.
3) WIND CHILLS LOWERING INTO THE SINGLE DIGITS ABOVE/BELOW ZERO.
LONG TERM
(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 320 AM CST FRI JAN 18 2019
SATURDAY NIGHT THROUGH SUNDAY NIGHT
COLD WEATHER WILL BE THE MAIN STORY FOR THE SECOND HALF OF THE
WEEKEND. WE'LL HAVE BELOW NORMAL TEMPS, BUT NOTHING TOO UNUSUAL FOR
MID JANUARY. FORECAST LOWS ARE IN THE SINGLE DIGITS ABOVE AND
BELOW ZERO. THE GOOD NEWS IS WINDS WILL BE LIGHT, KEEPING WIND
CHILLS GENERALLY BETWEEN -10 TO -5 F. WITH THE FRESH SNOW COVER
AND LOW-LEVEL INVERSION, TEMPS WILL STRUGGLE TO REBOUND INTO THE
LOW TO MID TEENS SUNDAY AFTERNOON.
THERE IS ALSO A CHANCE FOR A BAND OF LIGHT SNOW TO DRIFT IN FROM
THE NW ON SUNDAY AS 850MB WARM AIR ADVECTION RAMPS UP, BUT MODELS
ARE NOT IN VERY GOOD AGREEMENT ON THE PLACEMENT. CHANCES WILL
LIKELY HAVE TO BE INCREASED IN LATER FORECAST UPDATES. MODEL
SOUNDINGS HAVE A VERY DEEP DGZ, EXTENDING FROM THE SURFACE TO ~3
KM. IF THIS OCCURS, SNOW TO LIQUID RATIOS WOULD PROBABLY EXCEED
25:1 AND IT WOULDN'T TAKE MUCH TO GET A FEW INCHES OF VERY FLUFFY
SNOW IN A NARROW SWATH. OVERALL, CONFIDENCE IS LOW ON THE
PLACEMENT -- WE SHOULD HAVE A BETTER IDEA LATER TODAY OR TONIGHT.
MONDAY ON
ACTIVE WINTER WEATHER IS EXPECTED INTO NEXT WEEK. ANOTHER AREA OF
LOW PRESSURE IS FORECAST TO PASS THROUGH THE UPPER MISSISSIPPI
VALLEY MONDAY NIGHT AND TUESDAY. LATEST MODEL BLEND SURFACE AND
850MB TEMPS MODERATE TO ABOVE FREEZING OVER ROUGHLY THE SOUTH
HALF OF THE CWA, WHICH COULD BRING THE RAIN/SNOW LINE INTO AT
LEAST THE SOUTHERN FORECAST AREA.
DEPENDING ON THE EVENTUAL TRACK AND STRENGTH OF THIS LOW, ANOTHER
ROUND OF ACCUMULATING SNOW IS POSSIBLE FOR PARTS OF THE AREA. RIGHT
NOW THE GFS AND ECMWF FAVOR THE NORTHERN AND WESTERN SECTIONS.
THE MAIN DIFFERENCE BETWEEN THE TWO MODELS IS THE ECMWF IS A
LITTLE FURTHER SOUTH WITH THE LOW TRACK AND IS A SLIGHTLY COLDER
SOLUTION. MAKE SURE TO KEEP UP WITH THE LATEST FORECASTS THROUGH
THE WEEKEND.
BELOW NORMAL TEMPERATURES ARE EXPECTED FOR THE MIDDLE AND END OF
NEXT WEEK. THE NEXT CHANCE FOR LIGHT SNOW FROM A WEAK CLIPPER SYSTEM
IS NEXT THURSDAY. UTTECH
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 509 AM CST FRI JAN 18 2019
SATELLITE TRENDS SHOW THE BACK EDGE OF THE MVFR STRATUS HAS SLOWED
CONSIDERABLY, AND NOW APPEARS UNLIKELY TO REACH THE TERMINALS AHEAD
OF AN APPROACHING WINTER STORM. THIS STORM WILL SPREAD SNOW AND
IFR CONDITIONS INTO CID AND DBQ MID TO LATE AFTERNOON, REACHING MLI
AND BRL EARLY EVENING. WIDESPREAD LIFR CONDITIONS THEN LIKELY
BY LATE EVENING THROUGH OVERNIGHT WITH ACCUMULATING SNOW AND GUSTY
NORTHEAST WINDS CAUSING SOME DRIFTING SNOW AND POSSIBLE BLOWING
SNOW, WHICH MAY CONTRIBUTE TO REDUCTIONS IN VISIBILITY. THE SNOW
SHOULD TAPER OFF LATE TONIGHT THROUGH MID MORNING SATURDAY, BUT GUSTY
WINDS WILL LIKELY LEAD TO CONTINUING BLOWING SNOW WITH PERIODIC
VISIBILITY RESTRICTIONS ON SATURDAY.
DVN WATCHES/WARNINGS/ADVISORIES
IA...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST
SATURDAY FOR CEDAR-CLINTON-DES MOINES-HENRY IA-IOWA-JACKSON-
JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA-MUSCATINE-SCOTT-VAN
BUREN-WASHINGTON.
WINTER STORM WARNING FROM NOON TODAY TO NOON CST SATURDAY FOR
BENTON-BUCHANAN-DELAWARE-DUBUQUE-JONES-LINN.
IL...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST
SATURDAY FOR CARROLL-JO DAVIESS-ROCK ISLAND-STEPHENSON-
WHITESIDE.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 3 PM CST SATURDAY
FOR BUREAU-HANCOCK-HENDERSON-HENRY IL-MCDONOUGH-MERCER-
PUTNAM-WARREN.
MO...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO NOON CST
SATURDAY FOR CLARK-SCOTLAND.
SYNOPSIS...MCCLURE
SHORT TERM...MCCLURE
LONG TERM...UTTECH
AVIATION...MCCLURE
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