Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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431
FXUS63 KDVN 081733
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1133 AM CST MON FEB 8 2016

...AVIATION UPDATE...

.SYNOPSIS...
ISSUED AT 321 AM CST MON FEB 8 2016

SPS CURRENTLY IN EFFECT FOR ALL BUT BUREAU AND PUTNAM COUNTIES
TO HIGHLIGHT POTENTIAL FOR RAPID DROPS IN VISIBILITIES DUE TO THE
COMBINATION OF LIGHT TO MODERATE SNOW SHOWERS AND WIND GUSTS
BETWEEN 30-40 MPH.

TEMPS WILL SLOWLY FALL THIS MORNING THEN REMAIN STEADY THROUGH THE
AFTN. HIGHS ARE FORECAST IN THE UPPER TEENS NW DVN CWA TO MID 20S
OVER THE SE.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 321 AM CST MON FEB 8 2016

TODAY...

EXPECTED IMPACTS...MAIN IMPACT PERIOD IS THROUGH THE LATE MORNING
WHEN SNOW SHOWERS...PRODUCING POWDERY SNOW...WILL BE MOST NUMEROUS
AND NW WINDS WILL REMAIN STRONG...GUSTING BETWEEN 30-40 MPH. THESE
TWO ELEMENTS TOGETHER WILL CAUSE VISIBILITY RESTRICTIONS TO LESS
THAN A MILE IN LOCALIZED AREAS.

FORCING FOR PRECIPITATION...A 500MB VORT MAX SITUATED OVER SE
MINNESOTA IS FORECAST TO MOVE SOUTHWARD OVER THE NEXT SEVERAL
HOURS SPREADING AN AREA OF MID-LEVEL SYNOPTIC ASCENT VIA PVA OVER
EASTERN IOWA/WESTERN ILLINOIS/AND NE MISSOURI.

NUMEROUS SNOW SHOWERS ARE FORECAST THROUGH THE MID MORNING. SOME
WILL BE CONVECTIVE IN NATURE EARLY THIS MORNING GIVEN THE NEAR DRY
ADIABATIC 900-850MB LAPSE RATES/PRESENCE OF SBCAPE UP TO 25
J/KG/AND COLLOCATION WITH A ZONE OF 925-850MB FRONTOGENETIC
RESPONSE.

A DEEP DENDRITIC SNOW GROWTH ZONE AROUND 200MB SUPPORTS FORMATION
OF POWDERY SNOW WITH SLRS BETWEEN 15-TO-20 TO 1. HOWEVER...STRONG
WINDS SHOULD KEEP THE SLRS IN CHECK AS DENDRITIC AGGREGATES WILL
TEND TO FRAGMENT AS THEY FALL TOWARD THE SFC.

SNOW ACCUMULATIONS...AROUND A HALF INCH FOR MOST OF THE DVN CWA
WITH POCKETS NEAR AN INCH THROUGH THIS AFTN. ADDITIONAL LIGHT
SNOWFALL IS LIKELY TONIGHT INTO TUESDAY ESPECIALLY IN THE
COUNTIES ALONG AND EAST OF MISSISSIPPI.

TONIGHT...GUSTY NW WINDS WILL CONTINUE...WELL-MIXED DRY ADIABATIC
BOUNDARY LAYER IS SHOWN ON BUFKIT FORECAST SOUNDINGS WITH MIXING
UP TO 875MB. NW WINDS WILL GUST BETWEEN 25-35 MPH INTO TUESDAY
MORNING.

LACK OF ORGANIZED/DEEP FORCING FOR ASCENT WILL PRECLUDE
WIDESPREAD SNOW SHOWERS BUT ENOUGH LOW-LEVEL SATURATION AND WEAK
FORCING FOR SCT LIGHT SNOW SHOWERS AND FLURRIES TO CONTINUE ON AND
OFF THROUGH THE NIGHT. ADDITIONAL ACCUMULATIONS FOR MOST AREA
SHOULD BE AT OR BELOW A HALF INCH INTO TUESDAY MORNING. UTTECH.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 321 AM CST MON FEB 8 2016

LIGHT SNOW IS EXPECTED TO LINGER TUESDAY...MAINLY ACROSS NORTHWEST
ILLINOIS. A NORTHWEST WIND WILL GUST AROUND 25 MPH...BUT NO
SIGNIFICANT TRAVEL ISSUES ARE EXPECTED. STRONG COLD AIR ADVECTION
WILL CONTINUE IN THE AMPLIFYING UPPER FLOW. TUESDAY NIGHT MAY BE THE
COLDEST PERIOD OF THE WEEK...WITH LOWS IN THE SINGLE DIGITS ABOVE
AND BELOW ZERO. WIDESPREAD WIND CHILL VALUES OF 10 TO 20 BELOW ZERO
ARE FORECAST...WITH POTENTIAL FOR ADVISORY CRITERIA ACROSS THE
NORTHWEST COUNTIES LATE TUESDAY NIGHT INTO WEDNESDAY MORNING. EXPECT
GRADUALLY MODERATING TEMPS BEGINNING THURSDAY...WITH THE POSSIBLE
EXCEPTION OF A BRIEFLY COLDER PERIOD ON SATURDAY.

AS IS CUSTOMARY WITH NORTHWEST FLOW...THE VARIOUS SYNOPTIC SCALE
MODELS ARE LATCHING ON TO SEVERAL PIECES OF ENERGY AT TIMES. THE
00Z/08 GFS/GEM SUPPORT A WAVE ON WEDNESDAY NIGHT...WHILE THE 00Z/08
EC/GEM SUPPORTS A MORE VIGOROUS SHORT WAVE TROUGH ON WEDNESDAY
NIGHT. THE EC ALSO BRINGS ANOTHER WEAK SYSTEM THROUGH THE AREA ON
SUNDAY. AFTER COLLABORATION WITH NEIGHBORS...HAVE OPTED TO MAINTAIN
THE CONSENSUS BLEND...WITH ONLY CHANCE POPS ON SUNDAY FOR NOW. THERE
IS STILL PLENTY OF TIME TO RESOLVE THE MODEL DIFFERENCES OVER THE
NEXT SEVERAL DAYS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1131 AM CST MON FEB 8 2016

WIDESPREAD MVFR CONDITIONS WERE ACROSS EASTERN IOWA AND NORTHERN
ILLINOIS WITH LIGHT SNOW. MVFR CONDITIONS WILL CONTINUE THROUGH
18Z/09 WITH POCKETS OF VFR CONDITIONS. SNOW SHOWERS WILL CONTINUE
THROUGH 01Z/09 THAT MAY BRIEFLY CREATE IFR CONDITIONS IF THEY
IMPACT A TAF SITE. A NEW ROUND OF SNOW SHOWERS ARE EXPECTED TO
DEVELOP AFT 16Z/09.

&&

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

$$

SYNOPSIS...UTTECH
SHORT TERM...UTTECH
LONG TERM...RP KINNEY
AVIATION...08



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