Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 260553
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1153 PM CST SUN JAN 25 2015

.UPDATE...
ISSUED AT 940 PM CST SUN JAN 25 2015

CHALLENGING LOW TEMP FCST WITH SKIES CLEARING WITH EXCEPTION OF
FAR WEST/SOUTHWEST WHERE STRATUS LINGERS... AND WHERE SKIES
HAVE CLEARED SATELLITE SHOWS NOT FOR MUCH LONGER WITH HIGH
CLOUDS QUICKLY APPROACHING. ALSO... OVERNIGHT INTO MONDAY AM
AS THE FLOW IN 1500-2500 FT AGL LAYER SHIFTS TO WEST/SOUTHWEST
THIS SHOULD ADVECT IN STRATUS OVER MUCH OF CWA. BOTTOM LINE
GIVEN THE COMPLEX SKY COVER REST OF TONIGHT HARD TO MAKE ANY
ADJUSTMENTS TO LOWS AND ONLY TWEAKED DOWN FEW SITES FROM QUAD
CITIES N/NE WITHIN THE CLEAR WEDGE ATTIM.

AFTER LOOKING AT 18Z MODEL SUITE AND SOME OF THE LATEST HI-RES
AND INCOMING 00Z MODEL DATA IT IS LOOKING MORE LIKELY THAT
MORE OF THE CWA WILL SEE PERIOD OF SNOW ON MONDAY WITH LIGHT
ACCUMS AROUND 1 INCH OR LESS. MODELS SHOW ABOUT A 1-3 HR PERIOD
OF STRONG UPGLIDE OVER QUICK MOVING WARM FRONT AND STRONG THERMAL
GRADIENT. DEVELOPMENT 13Z-15Z PORTIONS OF WEST/NORTHWEST CWA THEN
SWEEPING EAST EXITING FAR EAST CWA BY AROUND 21Z. SOME OF THE
LATEST GUIDANCE IS INDICATING QUITE A VIGOROUS SHOT OF OMEGAS IN
THE DENDRITIC GROWTH ZONE WHICH COULD RESULT IN A QUICK HITTING
BURST OF DENDRITES AND RAPID SNOW ACCUM IN SOME AREAS. BASED ON
THIS HAVE BEGUN TRENDING FORECAST TOWARD EXPANDING AND INCREASING
SNOW CHANCES ON MONDAY. UPDATED GRIDS/ZFP/PFM SENT.

&&

.SYNOPSIS...
ISSUED AT 226 PM CST SUN JAN 25 2015

DEPARTING FAST MOVING CLIPPER SYSTEM NOW IN SOUTHERN ILLINOIS HAS
DEPOSITED 1 TO 2 INCHES OF SNOW OVER MOST LOCATIONS OVER NORTHERN
2/3 OF FORECAST AREA AND LESS THAN AN INCH OVER THE FAR SOUTH.
SATELLITE TRENDS SUPPORT SURFACE ANALYSIS OF AT LEAST PARTIAL
CLEARING TONIGHT WITH LIGHT WINDS WITH NEXT SYSTEM THAT IS WEAKER
AND FURTHER NORTH FROM DAKOTAS TO PASS DURING THE DAY MONDAY.
STRONG NOREASTER TO KEEP AREA QUIET AND SEASONABLY COOL THROUGH
WEDNESDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 226 PM CST SUN JAN 25 2015

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...GOOD TO FAIR WITH MAIN
ISSUE CLEARING TONIGHT THAT COULD ALLOW FOR MINS TO FALL LOWER THAN
FORECAST WITH PATCHY FOG DUE TO LIGHT WINDS FOR SEVERAL HOURS.
SECONDARY ISSUE IS SNOW AMOUNTS ON MONDAY OF A FEW TENTHS OVER NE
1/3 OF AREA DEPENDENT UPON IF BL MOISTURE LEVELS ARE THERE WHICH
IS MARGINAL.

TONIGHT...OVERALL PARTLY CLOUDY WITH LIGHT NORTHERLY WINDS THIS EVENING
BECOMING CALM FOR SEVERAL HOURS. THIS WOULD SUGGEST WITH FRESH SNOW
OF GOING COLDER THAN GUIDANCE WITH PATCHY FOG POSSIBLE AFTER MIDNIGHT
FOR LATER SHIFTS TO ASSESS. IDEAL CONDITIONS COULD SEE MINS UP TO
5 DEGREES OR MORE COLDER IN FAVORED LOW LYING AREAS. INCREASING CLOUDS
TOWARD DAYBREAK SUGGEST MOST MINS TO OCCUR BEFORE 6 AM.

MONDAY...WEAK AND FAST MOVING WARM FRONT TO SUGGEST FLURRIES AND A
CHANCE OF LIGHT SNOW OVER NE 1/3 OF AREA WITH TRACE TO MAY NEAR A
HALF INCH IN FAR NE SECTIONS OF ILLINOIS. MAX TEMPS TO SHOW A STRONG
GRADIENT WITH AROUND 30F IN FAR NE TO UPPER 40S SW WITH MORE SUNSHINE
AND SW WINDS.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 226 PM CST SUN JAN 25 2015

OVERVIEW...A LONGWAVE TROUGH WILL DEVELOP OVER THE EASTERN U.S.
KEEPING THE MIDWEST IN NORTHWEST FLOW ALOFT THROUGH TUESDAY. THEN A
RETURN TO A SPLIT UPPER-LEVEL FLOW IS FORECAST ALONG WITH TEMPS
ABOUT 10 F DEGREES ABOVE AVERAGE IN THE 30S/40S ON WEDNESDAY WITH A
SLIGHT COOL DOWN FOR THURSDAY. A CLIPPER SYSTEM MAY BRING LIGHT
PRECIP TO E IOWA/W ILLINOIS WEDNESDAY NIGHT INTO THURSDAY. THERMAL
PROFILES SUGGEST RAIN INITIALLY POSSIBLY ENDING AS SNOW SHOWERS.

MONDAY NIGHT...HAVE SLIGHT CHANCES FOR -FZDZ WITH LOW STRATUS
OVERHEAD AND LACK OF SATURATION AT -10 C OR COLDER. THINKING ANY
LIGHT PRECIP WOULD BE PATCHY BUT WILL HAVE TO MONITOR.

MAX TEMPS TUESDAY THROUGH THURSDAY...BLENDED THE ECMWF IN WITH THE
CONSENSUS BLEND TO ESSENTIAL TIGHTEN THE MAX T GRADIENT ACROSS THE
CWA...MAKING IT WARMER OVER THE SW AND COOLER OVER THE NE WHERE
STRATUS WILL BE MORE STUBBORN AND SNOW FIELD IS MORE PREVALENT.
INCORPORATED THE CONSALL WITH THE SUPERBLEND ON THU TO NUDGE MAX
TEMPS DOWN ACROSS NORTHERN THIRD OF FORECAST AREA. NORTHERLY FLOW
AND POTENTIAL STRATUS WOULD SUGGEST COOLER TEMPS.

TUESDAY...IMPRESSIVE MID-LEVEL RIDGE FORMING OVER THE CENTRAL U.S.
UPSTREAM OF THE STRONG EAST COAST TROUGH. WAA WILL CONTINUE TO
INCREASE 1000-500 MB THICKNESS THROUGH THE DAY...REACHING NEAR 546
DAM BY THE EVENING. CURRENT FORECAST IS FOR MID 40S IN THE SW DVN
CWA TO THE LOWER 30S NEAR FREEPORT WHERE STRATUS MAY HANG ON LONGER.
OTHERWISE...DRY CONDITIONS EXPECTED.

WEDNESDAY...SW TO NE TEMP GRADIENT ACROSS THE MIDWEST LOOKS TO PEAK
ON WED. MID 60S ARE FORECAST AS CLOSE AS W MISSOURI. A SHORTWAVE
TROUGH WILL MOVE INTO THE CENTRAL/NORTHERN PLAINS AND RESULTANT SFC
LOW WILL FORM DOWNSTREAM...REACHING THE KANSAS CITY AREA BY THE
EVENING. THIS METEOROLOGICAL SETUP PUTS E IOWA AND W ILLINOIS IN A
WAA FLOW IN ADVANCE OF THE SFC LOW. 1000-500 MB THICKNESS WILL PEAK
AS HIGH AS 552 DAM AND 850 TEMPS NEAR +4-6 C.

THERE ARE CHANCES FOR LIGHT PRECIP MAINLY IN THE FORM OF RAIN WED
NIGHT. CAA ON THE BACK SIDE OF THE SFC LOW SHOULD COOL THE THERMAL
PROFILE ENOUGH FOR ANY RESIDUAL SHOWERS TO CHANGE TO LIGHT SNOW.

THURSDAY AND FRIDAY...500 MB FLOW BECOMES MORE ZONAL AS MID-LEVEL
VORT. MAX DIVES DOWN TOWARD CALIFORNIA/ARIZONA AND ANOTHER ONE
ROTATES SOUTHWARD AROUND A QUASI-STATIONARY HUDSON BAY LOW INTO W
ONTARIO. THIS MAY BE THE FIST SIGN OF A SIGNIFICANT PATTERN CHANGE
TO COLDER TEMPS...POSSIBLY COMMENCING NEXT WEEKEND. THE CPC OUTLOOK
FOR THE FIRST WEEK OF FEBRUARY HAS A ~70% PROBABILITY FOR BELOW
NORMAL TEMPS OVER E IOWA/WESTERN ILLINOIS.

SATURDAY AND SUNDAY...THERE ARE MAJOR DIFFERENCES BETWEEN THE
GFS AND ECMWF REGARDING THE SHIFT TO COLDER TEMPS. THE ECMWF BRINGS
AN ARCTIC FRONT THROUGH ON SAT WITH 1000-500 MB THICKNESSES FALLING
TO SUB-504 DAM BY SUN. THE GFS HAS THE COLD FRONT COMING THROUGH
NEXT MON BUT IS MUCH WEAKER. CURRENT FORECAST ALIGNS WITH THE
CONSENSUS BLEND WITH SLIGHTLY BELOW AVG TEMPS BY SUN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1145 PM CST SUN JAN 25 2015

CIGS EXPECTED TO CONTINUE LOWERING INTO MVFR OVERNIGHT INTO EARLY
MONDAY AM AHEAD OF WARM FRONT... AND GENERALLY REMAIN MVFR
THROUGHOUT THE REST OF THE TAF CYCLE WITH PASSAGE OF WARM FRONT
FOLLOWED BY SURFACE TROUGH PASSAGE. MEANWHILE...FAST MOVING
CLIPPER SYSTEM WILL DIVE FROM MANITOBA INTO THE OHIO VALLEY BY
TUESDAY AM. THIS SYSTEM COUPLED WITH STRONG WARM ADVECTION SHOULD
PRODUCE PERIOD OF LIGHT SNOW ACROSS PORTIONS OF EASTERN IA AND
NORTHWEST IL BY MID MORNING THROUGH EARLY AFTERNOON. STRONG LIFT
IN THE DENDRITIC GROWTH ZONE SUPPORTS POTENTIAL FOR SOME SCATTERED
ROBUST SNOW SHOWERS WHICH COULD DROP VISIBILITY BRIEFLY BELOW 1
MILE. WINDS WILL INCREASE FROM SOUTH AND VEER TO S/SW AROUND 10
KTS MONDAY AM THEN BEGIN VEERING FURTHER TO WEST AND EVENTUALLY
NORTHWEST WITH SFC TROUGH PASSAGE LATER AFTERNOON INTO EARLY EVENING.


&&

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

$$

UPDATE...05
SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...UTTECH
AVIATION...05





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