Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 230534
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1134 PM CST THU JAN 22 2015

.UPDATE...
ISSUED AT 524 PM CST THU JAN 22 2015

BASED ON THE CURRENT RATE OF THE EASTWARD PROGRESSION OF THE BACK
EDGE OF THE STRATUS IN WESTERN IA...AND TRENDS OF THE HRRR AND RAP
THAT HAD A DECENT HANDLE ON THESE FEATURES...CLEARING WILL LIKELY
TAKE LONGER THAN ORIGINALLY EXPECTED. HAVE UPDATED THE FORECAST
FOR THE CLEARING TO REACH OUR WESTERN FORECAST AREA BORDER AROUND
MIDNIGHT...THEN CROSS THE MS RIVER AROUND 5 AM. THIS WOULD LEAVE
OUR ILLINOIS ZONES UNDER CLOUD COVER THROUGH THE NIGHT. FOR
NOW...HAVE MADE ONLY MINOR TWEAKS TO HOURLY TEMPERATURES...BUT
WILL NEED TO REASSESS FOR POSSIBLE WARMER LOWS WITH THE MORE
PERSISTENT CLOUD COVER.

&&

.SYNOPSIS...
ISSUED AT 346 PM CST THU JAN 22 2015

UPPER LEVEL TROUGH ALONG WITH A STRENGTHENING INVERSION AT 900 MB
TRAPPING THE LOW LEVEL MOISTURE BELOW...DESPITE SURFACE HIGH
PRESSURE OVER THE CWA. THIS HAS RESULTED IN AN EXTENSIVE AREA OF
STRATUS TODAY ACROSS THE CWA. 3 PM TEMPERATURES RANGED FROM THE
UPPER 20S TO MID 30S.

ELSEWHERE...SUBSIDENCE BEHIND THE DEPARTING TROUGH WAS CLEARING
THE SKIES IN WISCONSIN AND ALSO WESTERN IA/WESTERN MN. HOWEVER...THE
CLEARING HAS COME TO A GRINDING HALT IN SOUTHERN WI BUT CONTINUES
TO MAKE SLOW BUT STEADY PROGRESS EASTWARD IN WESTERN IA.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 346 PM CST THU JAN 22 2015

FORECAST FOCUS ON CLOUDS AND TEMPERATURES. WARMER ON FRIDAY.

TONIGHT...GRADUAL CLEARING FROM WEST TO EAST AS THE UPPER TROUGH
SHIFTS EAST AND THE FLOW BECOMES ANTI-CYCLONIC. THE SURFACE RIDGE
WILL BE SHIFTING TO OUR SOUTH ALLOWING WINDS TO BACK SOUTHWEST.
TEMPERATURES SHOULDN`T DROP TOO MUCH TONIGHT DUE TO SOUTHWEST WINDS
AND WEAK WARM AIR ADVECTION DEVELOPING. MINIMUM TEMPERATURES ARE
EXPECTED TO BE IN THE LOWER TO MID 20S...WITH THE COOLEST READINGS
IN FAR NW IL WHERE SEVERAL INCHES OF SNOW COVER EXISTS.

FRIDAY...SKIES WILL BE SUNNY IN THE MORNING THEN INCREASING CLOUDS
DURING THE AFTERNOON IN OUR NORTH...AS A WEAK SHORT WAVE DROPS
SOUTHEAST TOWARDS THE AREA IN THE NW FLOW ALOFT. WITH SOUTHWEST SURFACE
WINDS THIS SHOULD BOOST AFTERNOON TEMPERATURES INTO THE UPPER 30S
TO LOWER 40S AT MOST LOCATIONS.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 335 PM CST THU JAN 22 2015

CHANCE OF RAIN/SNOW LATE SAT NGT-SUN...OTHERWISE GENERALLY DRY WITH
TEMP MOSTLY NEAR TO ABOVE NORMAL.

FRIDAY NIGHT... WEAK AND QUICK MOVING UPPER AIR DISTURBANCE TO SWEEP
THROUGH THE GREAT LAKES WITH ATTENDANT SURFACE TROUGH PASSING
ACROSS CWA. WEAK FORCING AND LIMITED MOISTURE SHOULD PRECLUDE MUCH
MORE THAN JUST INCREASING CLOUDS AND POSSIBLY FEW FLURRIES OR PATCHY
DRIZZLE NORTHEAST IA INTO NORTHWEST IL DEPENDING ON ICE INTRODUCTION
AND DEPTH OF MOISTURE. MINIMAL COOLING POST TROUGH COUPLED WITH
CLOUDINESS LENDS SUPPORT FOR STAYING NEAR WARM SIDE OF GUIDANCE ON
LOWS AND GENERALLY IN THE UPPER 20S TO AROUND 30F.

SATURDAY AND SUNDAY... MODELS STILL VARY WITH TRACK OF FAIRLY VIGOROUS
CLIPPER SYSTEM LATE SATURDAY NIGHT ALTHOUGH STARTING TO SEE SOME
TRENDS AND CLUSTERING WITH 12Z MODEL SUITE. MOST NOTABLY THE GEM HAS
TRENDED MUCH FURTHER SOUTH FROM UPPER PENINSULA OF MI TO CENTRAL WI WHICH
IS CLOSER TO TRACK OF UKMET AND OPERATIONAL GFS. THE OPERATIONAL GFS IS
ACTUALLY A LITTLE FURTHER SOUTH OF ENSEMBLE MEAN AND NEARLY ALL OF THE
MEMBERS. MEANWHILE THE ECMWF CONTINUES TO REMAIN THE FURTHEST SOUTH TAKING
THE CLIPPER SYSTEM ACROSS THE CWA. A MORE NORTHEAST TRACK WOULD RESULT
IN TAPERED PCPN CHCS FROM WEST TO EAST WITH RAIN BEING THE MORE DOMINANT
PRECIPITATION TYPE WITH SOME LIGHT SNOW OR FLURRIES POSSIBLE IN
WRAP-AROUND. MEANWHILE A TRACK FURTHER SOUTHWEST SUCH AS SHOWN BY ECMWF
COULD RESULT IN MORE SNOW WITH LIGHT ACCUMULATIONS. WITH THE MAIN SYSTEM
IN QUESTION STILL OFF THE BRITISH COLUMBIA COASTLINE AND NOT WELL SAMPLED
YET BY RAOB NETWORK IT COULD TAKE ANOTHER 12-24 HRS BEFORE THAT OCCURS AND
BEFORE WE START SEEING BETTER MODEL CONSISTENCY WITH THE TRACK. FOR NOW
THOUGH WILL CONTINUE WITH CHANCE OF PCPN OVERNIGHT SATURDAY NIGHT
THROUGH SUNDAY... WITH MAINLY RAIN WITH SOME MIX OF SNOW NORTH TRANSITIONING
TO MIX OR SNOW SUNDAY. FEELING IS A MORE SOUTHERLY TRACK PERHAPS CLOSER
TO ECMWF OR BLENDED WITH GFS REASONABLE. AS PREVIOUS SHIFTS HAVE MENTIONED
THE ORIENTATION OF THE LEFT EXIT REGION OF 150+ KT JET WITH COMPACT
SHORTWAVE TROUGH FAVORS MORE DIGGING OF SYSTEM WHICH FITS CONCEPTUALLY WITH
SYSTEM ENTERING LONGWAVE TROUGH. THIS WOULD SUPPORT MORE SOUTHERLY TRACK
WHICH IS ALSO HINTED BY GFS ENSEMBLE WITH ITS LARGEST STANDARD DEVIATION
IN 500 MB HEIGHTS OVER EASTERN IA/NORTHWEST IL SUNDAY 12Z.

TEMPS SATURDAY AND SUNDAY WILL DEPEND ON TRACK OF CLIPPER SYSTEM... BUT
IN GENERAL MUCH OF THE PERIOD SHOULD BE ABOVE FREEZING AND ABOVE NORMAL
WITH AREA RESIDING IN WARM SECTOR AHEAD OF SYSTEM. EXCEPTION BEING
SUNDAY NIGHT IN WAKE OF DEPARTING SYSTEM AS NORTHERLY WINDS WILL USHER IN
COLDER AIR AND EXPECT LOWS SUNDAY NIGHT TO DIP DOWN WELL INTO THE 20S.

MONDAY THROUGH THURSDAY... MAINLY DRY WITH SOME SUGGESTION OF ANOTHER
CLIPPER SYSTEM AROUND TUESDAY AND POSSIBLY THURSDAY BUT CONFIDENCE ON
TRACK AND IMPACT TOO LOW FOR MENTIONABLE POPS AS IT APPEARS AT THIS TIME.
TEMPS TO TAKE A BIT OF A HIT MONDAY INTO TUESDAY WITH COLDER AIR AND
MAY NEED TO BE LOWERED A BIT MORE CLOSER TO NORMAL WITH ECMWF AND GFS
SHOWING 850 TEMPS AROUND -4C TO -10C FROM WEST TO EAST SUPPORTIVE OF
GRADIENT IN TEMPS AS WELL. ANOTHER ROUND OF MP AIRMASS SHOWN BY GFS AND
ECMWF TO RETURN TO MIDWEST MID-LATE WEEK WHICH SHOULD SEND TEMPS BACK
ABOVE NORMAL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1133 PM CST THU JAN 22 2015

A PERSISTENT DECK OF LOW CLOUDS WITH BASES AROUND 1200 TO 2000 FT
AGL WAS COVERING MOST OF IL AND THE EASTERN HALF OF IA THIS
EVENING...RESULTING IN WIDESPREAD MVFR CONDITIONS. THE BACK EDGE
OF THE CLOUDS OVER CENTRAL IA CONTINUES TO SLOWLY EDGE
EASTWARD...BUT ITS PROGRESS HAS SLOWED SOME THIS EVENING. THE
LATEST FORECASTS HAVE DELAYED THE EXPECTED CLEARING TREND AND
TRANSITION TO VFR CONDITIONS BY SEVERAL HOURS...NOT REACHING CID
UNTIL WELL AFTER MIDNIGHT AND THEN THE MS RIVER SITES CLOSER TO
SUNRISE. VFR CONDITIONS AND INCREASING SOUTHWEST WINDS ARE THEN
EXPECTED FOR THE REMAINDER OF FRIDAY.

&&

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

$$

UPDATE...SHEETS
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...05
AVIATION...SHEETS






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