Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 192343
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
543 PM CST FRI DEC 19 2014

.SYNOPSIS...
ISSUED AT 312 PM CST FRI DEC 19 2014

UPPER-LEVEL LOW WILL SLOWLY MOVE FROM SOUTHERN MANITOBA
THIS AFTN TO WESTERN ONTARIO THROUGH SATURDAY. THE TROUGH AXIS
ATTENDANT TO THIS FEATURE EXTENDS INTO NORTHERN NEBRASKA AND WILL
SWING THROUGH IOWA SATURDAY MORNING. THERE IS A LOT OF LOW-LEVEL
MOISTURE LOCATED IN THE SOUTHWESTERLY FLOW PRECEDING THE TROUGH
WHERE WIDESPREAD STRATUS IS FOUND ACROSS THE EASTERN PLAINS AND
MIDWEST.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 312 PM CST FRI DEC 19 2014

TONIGHT...TREND AFTER MIDNIGHT WILL BE FOR INCREASING CLOUDS
WITH CEILINGS LOWERING TO NEAR OR BELOW 1000 FEET AGL AS LOW-LEVEL
TROUGH APPROACHES AND INCREASES RH IN THE NEAR SFC-850 MB LAYER. NAM
AND SREF PRODUCE A FEW HUNDREDTHS OF PRECIPITATION THROUGH THE
OVERNIGHT PERIOD BUT FEEL THIS IS OVERDONE. IF LIGHT PRECIP WERE TO
OCCUR...IT WOULD MOST LIKELY BE LIGHT PATCHY FREEZING DRIZZLE SINCE
SATURATED CLOUD LAYER IS AT -8/-9 C OR WARMER...ALTHOUGH A FEW
SNOWFLAKES WOULD ALSO BE POSSIBLE. AT THIS POINT...NOT EXPECTING
WIDESPREAD -FZDZ. HOWEVER WITH TEMPS IN THE MID 20S TO NEAR 30 F
DEFINITELY A SITUATION TO MONITOR. HAVE SLIGHT CHANCE FOR -FZDZ
AFTER 3 AM ACROSS THE AREA WITH THE SLIGHT CHANCE CONTINUING
THROUGH EARLY SATURDAY MORNING.

SATURDAY...DEFINED VORTICITY MAX WILL MOVE EAST OF THE AREA BY
MIDDAY WHICH WILL SIGNIFICANTLY DRY OUT MID-LEVELS. LARGE-SCALE
SUBSIDENCE WILL DEVELOP AN INVERSION BETWEEN 900-850 MB...TRAPPING
LOWER LEVEL MOISTURE BENEATH IT. THUS IT WILL BE DIFFICULT TO GET
MUCH CLEARING THROUGH THE AFTN AND INTO THE NIGHTTIME.  925-850 MB
WAA WILL PROVIDE WEAK LIFT WITHIN A SATURATED ENVIRONMENT...
THEREFORE PATCHY DRIZZLE WILL BE POSSIBLE DURING THE MID/LATE AFTN.
HIGHS WILL BE IN THE MID 30S ON AVG.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 312 PM CST FRI DEC 19 2014

FORECAST PROBLEM OF THE DAY REMAINS THE STORM SYSTEM APPROACHING
THE AREA EARLY THIS WEEK AND WHAT KIND OF SENSIBLE WEATHER WE WILL
EXPERIENCE. LIKE YESTERDAY THERE IS GOOD AGREEMENT BETWEEN THE
MODELS THAT THE MIDWEST AND GREAT LAKES WILL SEE A STORM SYSTEM
MONDAY TH RU CHRISTMAS EVE...BUT SPECIFICS ARE DYNAMIC AND THUS
HARD TO NAIL DOWN.

THE SAME AS YESTERDAY...A SERIES OF SHORTWAVE TROFS AND VORT MAXES
WILL MOVE THROUGH THE FLOW THIS WEEKEND WITH A TROF APPROACHING
THE AREA AT THE BEGINNING OF THE EXTENDED PERIOD. GUIDANCE IS IN
GOOD AGREEMENT WITH THE POSSIBILITY OF MEASURABLE QPF WITH THE
SYSTEM ON SATURDAY NIGHT/SUNDAY AM. AT THIS TIME MODEL SOUNDINGS
SUGGEST A MIST EVENT WITH FREEZING MIST ACROSS THE NORTHERN AND
WESTERN ZONES. TEMPERATURES WARM TO ABOVE FREEZING ON SUNDAY
AFTERNOON AND TURNS TO ALL RAIN. IMPACTS FROM THIS SYSTEM COULD
LINGER THRU EARLY AFTERNOON ON SUNDAY.

ON MONDAY THE BETTER VORT MAX DIGS A TROF INTO THE CENTRAL UNITED
STATES LEADING TO AN ACTIVE WEEK IN TERMS OF WEATHER. MODELS
AGREE ON ONE THING AND THAT IS THERE IS A CHANCE FOR PRECIP MONDAY
THROUGH CHRISTMAS EVE. THE WAY WE GET THERE IS DIFFERENT WITH EACH
MODEL. CURRENT CONSENSUS GUIDANCE SUGGESTS MIST TRANSITIONING INTO
RAIN THROUGH TUESDAY 6Z..THEN A CHANCE OF SNOW MIXES IN WITH THE
RAIN IN OUR WESTERN ZONES. AS THE SYSTEM OCCLUDES...WE SEE SNOW ON
THE BACK END. WINDS LOOK TO BE GUSTY...ESPECIALLY ON TUESDAY PM
INTO WEDNESDAY. LOOKING AT SPECIFIC MODELS....THE GEM HAS THE
INITIAL LOW IN N WI AND THEN IT OCCLUDES AND DEVELOPS A LOW ACROSS
AR AND TN. THIS SOLUTION WOULD SUGGEST THAT MORE SNOW ACROSS OUR
EASTERN ZONES WOULD BE POSSIBLE. THE GFS HAS AN ELONGATED LOW
OVER IA AND MN...AND THEN DEVELOPS ANOTHER LOW OVER CHICAGO...IN
THIS CASE THE WHOLE CWA WOULD SEE SNOW. THE ECMWF IS EVEN MORE
DIFFERENT WHERE IT GOES NEGATIVELY TILTED ON WED AND DROPS MOST OF
THE SNOW TO OUR EAST. WHAT IM TRYING TO SAY IS THAT WE ARE NO
CLOSER TO A MODEL CONSENSUS THAN WE WERE YESTERDAY. THE SENSIBLE
WEATHER IS STILL UP IN THE AIR WITH THE MODELS CHANGING. I STILL
HAVE LOW CONFIDENCE IN THE SENSIBLE WEATHER FOR THE SYSTEM AS ANY
CHANGE IN STORM TRACK...DEVELOPMENT ETC..COULD LEAD TO A CHANGE IN
THE AFFECTS. AGAIN...THERE WILL BE A SYSTEM AFFECTING THE AREA
EARLY THIS WEEK AND THOSE WITH TRAVEL PLANS SHOULD CONTINUE TO PAY
ATTENTION TO FUTURE FORECASTS.

LOOKING TO CHRISTMAS DAY...THE DAY LOOKS DRY. ANOTHER STORM SYSTEM
APPROACHES THE AREA ON FRIDAY. THIS SYSTEM COULD BRING US A CHANCE
OF SNOW FOR THE LATTER PART OF THE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 543 PM CST FRI DEC 19 2014

A VERY SLOW MOVING RIDGE OF HIGH PRESSURE OVER WI AND IL WILL
SLOWLY MOVE EAST TONIGHT...ALLOWING LOW CLOUDS AND MVFR
CONDITIONS TO ITS WEST TO GRADUALLY BUILD EASTWARD TONIGHT AND
SATURDAY. CONFIDENCE IN THE TIMING OF THIS TRANSITION REMAINS
LOW...BUT THIS APPEARS MOST LIKELY TO OCCUR BETWEEN 03Z AND 06Z
THIS EVENING. THE FLIGHT RESTRICTIONS WILL MORE LIKELY DUE TO
LOWER CIGS FROM 1500 TO 2500 FT AGL...WHILE THERE IS A LOWER
POTENTIAL FOR LIGHT FOG TO DEVELOP AND LOWER VISIBILITIES INTO A
4SM TO 6SM RANGE AS WELL. THERE REMAINS A LOW POSSIBILITY FOR
LIGHT DRIZZLE OR FREEZING DRIZZLE...BUT CONFIDENCE OF ANY SIGNIFICANT
PRECIPITATION IS TOO LOW TO MENTION IN THE FORECAST. THE LOW
CLOUDS AND MVFR CONDITIONS WILL LINGER THROUGH SATURDAY WHILE
LIGHT SURFACE WINDS TURN MORE CONSISTENTLY FROM THE SOUTH.

&&

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

$$

SYNOPSIS...UTTECH
SHORT TERM...UTTECH
LONG TERM...GIBBS
AVIATION...SHEETS






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