Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 240545
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1145 PM CST MON FEB 23 2015

.SYNOPSIS...
ISSUED AT 253 PM CST MON FEB 23 2015

LATEST SFC ANALYSIS WAS INDICATING ARCTIC RIDGE AXIS SLIDING SOUTHWARD
TOWARD THE SOUTHEASTERN PLAINS/MID MS RVR AND OH RVR VALLEYS. THIS
WHILE SOUTHWESTERLY RETURN FLOW WAS ORGANIZING TO THE NORTH OF IT
ACRS THE NORTHERN PLAINS TO THE UPPER MS RVR VALLEY. ALOFT...WATER
VAPOR IMAGERY WAS INDICATING LEAD VORT MAX EMBEDDED IN STEEP
NORTHWESTERLIES DROPPING SOUTH ACRS THE LK WINNIPEG SOUTH CENTRAL
CANADA REGION...WHILE AN EVEN STRONGER WAVE NOTED FURTHER TO THE
NORTH JUST NORTHWEST OF HUDSON BAY.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 253 PM CST MON FEB 23 2015

TONIGHT...AS THE FIRST VORT MAX TAKES AIM AT SOUTHERN LK MI BY TUE
MORNING...IT/S TRAJECTORY TO CLIP THE NORTHEASTERN CWA AROUND
MIDNIGHT. BUT WITH SUCH DRY LOW TO MID LEVELS IN PLACE...ALL THIS
FEATURE TO DO IS INCREASE HIGH TO MID CLOUDS ACRS THE NORTHEASTERN
HALF OF THE CWA. WITH INCREASING LLVL SOUTHWESTERLIES BEHIND
DEPARTING RIDGE AXIS...12 HR LOWS TONIGHT WILL OCCUR DURING THE
EARLY EVENING FEW HRS AFTER SUNSET THEN STEADY TO SLOW RISE TREND
INTO TUE MORNING. DESPITE INCREASING SFC FLOW...WITH SUCH DRY AIR
AND LOW DPTS WILL UNDERCUT GUIDANCE LOWS SOME IN THE EAST HALF FOR
A BUFFER TO DROP TO BEFORE TEMPS STEADY OUT AGAIN. THIS COULD MAKE
FOR SOME EVENING WIND CHILLS DIPPING INTO AT LEAST THE MID TEENS
BELOW ZERO ACRS THE EASTERN THIRD OR MORE OF THE CWA. SFC WINDS
COULD REACH 10-20 MPH BY LATE NIGHT IN TIGHTENING RETURN FLOW
PRESSURE GRADIENT.

TUESDAY...AS THE NEXT MORE ROBUST UPPER WAVE CLIPPERS IT/S WAY ACRS
THE WESTERN GRT LKS AND TOWARD THE EASTERN OH RVR VALLEY BY TUE
EVENING...THE DVN CWA TO LIE ON IT/S WARM DRAW SIDE. MUCH OF THE CWA
COULD WARM WELL UP INTO THE 30S IN BRISK SFC WIND SOUTHWESTERLIES OF
15 TO 25 MPH AND GUSTS TO 30 MPH. ASSOCIATED SFC TROF WITH WAVE
ALOFT...TO SWEEP THROUGH BY LATE MORNING FOR WIND SWITCH TO THE
WEST OR NORTHWEST. IF ENOUGH LOWER LEVEL CU OR STRATOCU CAN EITHER
ADVECT IN BEHIND OR GET GENERATED BY THE PASSING LLVL TROF/VORT
ALOFT...THERE PROBABLY WILL BE SOME FLURRIES GETTING WRUNG OUT. NOT
SURE THE AFTERNOON LLVL LAPSE RATES AND MOISTURE WILL BE DEEP ENOUGH
FOR MORE ORGANIZED SNOW ROLLS DURING THE AFTERNOON...BUT CAN NOT RULE
IT OUT. WILL JUST ADVERTISE FLURRIES FOR NOW MAINLY ACRS THE
NORTHEASTERN HALF OF THE CWA.     ..12..

.LONG TERM...(TUESDAY NIGHT THROUGH NEXT MONDAY)
ISSUED AT 253 PM CST MON FEB 23 2015

QUIET AND COLD CONDITIONS WILL BE SEEN ACROSS THE AREA TUESDAY NIGHT
AS THE ARCTIC HIGH SLOWLY MOVES INTO THE GREAT LAKES. TEMPERATURES
WILL AVERAGE BELOW NORMAL. ATTENTION THEN TURNS TO THE APPROACHING
CLIPPER SYSTEM.

BASED ON THE PROXIMITY OF THE ARCTIC HIGH...WEDNESDAY MORNING WILL
START OUT DRY. BY MID TO LATE MORNING SOME FLURRIES OR VERY LIGHT
SNOW SHOULD BEGIN MOVING INTO THE WESTERN AREAS AND SLOWLY SPREAD
EAST DURING THE AFTERNOON. THE BETTER FORCING/MOISTURE RUNS FROM
SOUTHERN IOWA INTO MISSOURI. HOWEVER...THERE SHOULD BE A RESPECTABLE
BAND OF SNOW THAT SLOWLY MOVES FROM CENTRAL IOWA INTO SOUTHEAST
IOWA/NORTHEAST MISSOURI DURING THE AFTERNOON. DRIER AIR FEEDING IN
FROM THE NORTH SHOULD RESULT IN A SHARP GRADIENT BETWEEN NO
SNOW/SNOW AND ACCUMULATING SNOW.

THE FORCING/MOISTURE SLOWLY WEAKENS WEDNESDAY AFTERNOON AND INTO
WEDNESDAY EVENING. THUS THE SOUTHWEST THIRD OF THE AREA WILL HAVE
THE BETTER CHANCES AT SEEING ACCUMULATING SNOW. THE SNOW SHOULD
QUICKLY END FROM NORTHWEST TO SOUTHEAST BY LATE WEDNESDAY NIGHT.

AS FOR SNOW AMOUNTS...AN INCH OF SNOW SHOULD OCCUR SOUTH OF A VINTON
IA TO MONMOUTH IL LINE. AMOUNTS OF 2 TO 3 INCHES MAY BE POSSIBLE
SOUTH OF A WILLIAMSBURG IA TO KEOKUK IA LINE. NORTH OF A VINTON TO
MONMOUTH LINE AMOUNTS LESS THAN AN INCH ARE POSSIBLE THAT WILL TAPER
QUICKLY DOWN TO ONLY TRACE AMOUNTS.

THURSDAY WILL BE QUIET AND DRY AS THE NEXT ARCTIC HIGH BEGINS
BUILDING INTO THE MIDWEST. TEMPERATURES WILL CONTINUE TO BE 20
DEGREES BELOW NORMAL.

THURSDAY NIGHT ON...
THURSDAY NIGHT THROUGH FRIDAY NIGHT THE MODEL CONSENSUS HAS ANOTHER
ARCTIC HIGH MOVING THROUGH THE MIDWEST PRODUCING QUIET AND COLD
CONDITIONS. TEMPERATURES WILL AVERAGE WELL BELOW NORMAL. ATTENTION
THEN TURNS TO THE WEEKEND STORM SYSTEM.

SATURDAY THROUGH SUNDAY NIGHT. CONFIDENCE THAT THERE WILL BE A STORM
IS HIGH. HOWEVER...THERE IS A WIDE RANGE OF SOLUTIONS ON WHERE THE
STORM WILL TRACK SO CONFIDENCE ON PRECIPITATION TYPE...TIMING...AND
AMOUNTS ARE QUITE LOW. THE POSSIBILITY DOES EXIST THAT THIS STORM
SYSTEM MAY SLOW DOWN AND ARRIVE SATURDAY AFTERNOON OR NIGHT.

CONSIDERABLE COLD AIR WILL BE ACROSS THE AREA SATURDAY AND SATURDAY
NIGHT SO THE PRECIPITATION TYPE SHOULD BE ALL SNOW. THUS SNOW SHOULD
DEVELOP OR SPREAD INTO THE AREA SATURDAY AND OVERSPREAD MOST IF NOT
ALL OF THE AREA SATURDAY NIGHT.

THUS THE MODEL CONSENSUS SATURDAY/SATURDAY NIGHT HAS SLIGHT
CHANCE/CHANCE POPS AND CHANCE/LIKELY POPS RESPECTIVELY.

ON SUNDAY...TWO OF THE MODELS ARE SUGGESTING AN INFLUX OF WARM AIR
ALOFT INTO THE SOUTHERN THIRD OF THE AREA. AT THE LOW LEVELS...
RELATIVELY DRIER AND COLDER AIR WILL CONTINUE TO FLOW INTO THE AREA.
THUS THE THERMAL PROFILES SUPPORT THE POTENTIAL FOR THE ATMOSPHERIC
COLUMN TO COOL AS PRECIPITATION CONTINUES. THUS THE POTENTIAL IS
THERE FOR A MIX OF SLEET AND FREEZING RAIN OCCURRING WITH THE WARMER
AIR ALOFT ACROSS ABOUT THE SOUTH THIRD OF THE AREA WHILE SNOW
CONTINUES ACROSS THE NORTHERN HALF.

COLDER AIR MOVING IN BEHIND THE STORM SUNDAY NIGHT WOULD CHANGE ANY
MIXED PRECIPITATION BACK TO ALL SLOW AND PRECIPITATION WOULD THEN
SLOWLY END FROM WEST TO EAST OVERNIGHT.

SO...THE MODEL CONSENSUS HAS LIKELY POPS ON SUNDAY AND CHANCE POPS
SUNDAY NIGHT.

SNOW AMOUNTS FROM THE VARIOUS MODELS RANGE FROM A DUSTING TO
POTENTIALLY HEAVY AMOUNTS. GIVEN THE WIDE RANGE BETWEEN THE MODEL
SOLUTIONS...IT WOULD NOT BE PRUDENT TO CONSIDER PRELIMINARY AMOUNTS
THIS FAR OUT. ADDITIONALLY...THERE ARE INDICATIONS THAT THE OVERALL
FLOW PATTERN ACROSS NORTH AMERICA WILL BE CHANGING STARTING THIS
WEEKEND. WHEN THIS OCCURS...PREDICTABILITY BY THE MODELS DROPS.

REGARDLESS...THIS STORM SYSTEM SHOULD BE WATCHED WITH CAUTION AS THE
WEEK PROGRESSES.

ON MONDAY...THE MODEL CONSENSUS HAS DRY CONDITIONS AS A CANADIAN
HIGH BUILDS INTO THE MIDWEST. TEMPERATURES WILL CONTINUE TO AVERAGE
BELOW NORMAL.     ..08..

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1139 PM CST MON FEB 23 2015

GENERALLY VFR CONDITIONS TO CONTINUE FOR AT LEAST THE NEXT 24 HOURS
EXCEPT POSSIBLE PERIODS OF HIGH END MVFR CONDITIONS AFTER FRONTAL
PASSAGE AT DBQ/CID TUESDAY AFTERNOON. PARTLY CLOUDY SKIES OF HIGH
CLOUDS OVERNIGHT WITH SW WINDS INCREASING TO 10 TO 20+ KTS BY THE
LATE OVERNIGHT HOURS. GENERALLY MOSTLY CLOUDY SKIES CAN BE EXPECTED
TUESDAY WITH WINDS SHIFTING TO THE WEST AND THEN NORTHWEST AT 15
TO 25+ KTS BY MID TO LATE AFTERNOON. ANY CLOUD BASES SHOULD BE
3-8+K AGL BEFORE FRONTAL PASSAGE WITH AGAIN...MARGINAL MVFR POSSIBLE
NORTH OF I-80 IN THE AFTERNOON. SKIES TO CLEAR TUESDAY EVENING WITH
WINDS DIMINISHING TO 5 TO 10 KTS.

&&

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

&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...08
AVIATION...NICHOLS






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