Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 242115
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
315 PM CST SAT JAN 24 2015

.SYNOPSIS...
ISSUED AT 239 PM CST SAT JAN 24 2015

ANALYSIS AT 2 PM SHOWS TWO LOBES OF ENERGY DIVING SOUTHEAST FROM ALBERTA
INTO WESTERN NEBRASKA. STRONGEST ENERGY STILL IN CANADA CLEARLY SHOWS
SYSTEM TO DIG FURTHER SOUTH WITH SECOND VORT MAX TO CREATE LOTS OF PRECIPITATION
ALONG I-70 CORRIDOR MISSOURI INTO ILLINOIS TO LOWER FORCING WITH LEAD
ENERGY CENTER AND DEFORMATION ON NORTH SIDE OF SURFACE LOW OVER FORECAST
AREA. THIS WILL LEAD TO LIGHTER SNOW TOTALS LATE TONIGHT AND THROUGH
SUNDAY MID DAY. WEST WINDS WITH FAIR SKIES ALLOWING FOR TEMPERATURES
TO RISE WELL INTO THE 40S TO NEAR 50 DEGREES AT 2 PM IN WEST SECTIONS.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 239 PM CST SAT JAN 24 2015

SHORT TERM FORECAST CONFIDENCE ASSESSMENT...FAIR OR AVERAGE WITH MAIN
ISSUE RISK OF LOCALIZED 3 INCH SNOW TOTALS BETWEEN HIGHWAY 34 AND SOUTH
OF I-80 IF SECOND ENERGY CENTER CAUSES A DECENT DEFORMATION ZONE LATE
MORNING. ALSO QUESTION OF HOW QUICKLY RAIN CHANGES TO SNOW WITH PROFILES
SUGGESTING ANY SUSTAINED PRECIPITATION SHOULD CHANGE TO SNOW WITHIN
AN HOUR OR SO DUE TO EVAPORATIVE COOLING. ANOTHER ISSUE IS STRENGTH
OF WINDS AND FALLING TEMPERATURES BY SATURDAY AFTERNOON WITH SOME GUSTS
TO NEAR 35 MPH POSSIBLE THAT MAY ALLOW FOR MINOR DRIFTING OF SNOW.

TONIGHT...SKIES TO BECOME CLOUDY WITH LIGHT SPRINKLES OR LIGHT SHOWERS
DEVELOPING OR MOVING INTO NW SECTIONS SHORTLY BEFORE MIDNIGHT. AGAIN
ANY DECENT PRECIPITATION SHOULD MIX WITH OR CHANGE TO SNOW AS COVERAGE
INCREASES FROM NW TO SE OVERNIGHT WITH SNOW LINE LIKELY TO BE SOUTH
OF HIGHWAY 30 BY 6 AM. TEMPERATURES SHOULD BE NEAR 32 DEGREES AND COMBINED
WITH OUR GROUND SOILS ABOVE FREEZING LIMITING SNOW ACCUMULATIONS ON
ROADS INITIALLY. INDICATIONS OF A TENTH OR TWO OF SNOW ALONG HIGHWAY
30 BY DAYBREAK TO NEAR 1 INCH ALONG AND NORTH OF HIGHWAY 20 IN IOWA.
TEMPERATURES SHOULD REMAIN ABOVE FREEZING FOR MINS ALONG AND SOUTH
OF I-80 CORRIDOR.

SUNDAY...SURFACE LOW TO MOVE SOUTH WITH INCREASING NE WINDS OF 15 TO
30+ MPH OVER ALL THE AREA BY NOON. LIGHT TO MODERATE SNOW OF 1 TO 3
HOURS EXPECTED MOST AREAS AS SYSTEM SLIDES SOUTH. MOST LOCATIONS ALONG
AND SOUTH OF HIGHWAY 30 TO ALONG HIGHWAY 34 SHOULD RECEIVE 1 TO 2 INCHES
WITH RISK OF ISOLATED 3 INCHES POSSIBLE WITH SECOND DEFORMATION ZONE
SOUTH OF I-80 LATE MORNING INTO EARLY AFTERNOON FOR LATER SHIFTS TO
MONITOR DUE TO SECOND ENERGY CENTER PHASING WITH FIRST ENERGY CENTER
THAT ARRIVES LATE TONIGHT. HIGHS NEAR 8 AM MOST LOCATIONS WITH FALLING
TEMPERATURES INTO THE 20S ALONG WITH INCREASING NE WINDS THAT MAY ALLOW
FOR MINOR DRIFTING OF THE WET SNOW WITH 10-12 TO 1 RATIOS EXPECTED.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 239 PM CST SAT JAN 24 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. A CLIPPER SYSTEM
MAY BRING LIGHT PRECIP TO THE MIDWEST WEDNESDAY NIGHT. THERMAL
PROFILES SUGGEST RAIN INITIALLY POSSIBLY CHANGING TO SHOW SHOWERS
BY THURSDAY MORNING.

MONDAY...THERE WILL BE A LARGE LOW PRESSURE SYSTEM DEVELOPING ALONG
THE EAST COAST. THE MIDWEST WILL BE ON THE WESTERN SIDE OF THE
LONGWAVE MID/UPPER-LEVEL TROUGH. WAA WILL BE ONGOING THROUGH THE DAY
AS 850 MB TEMPS WARM TO NEAR -2 C AND 1000-500 MB THICKNESSES RISE
TO ~540 DAM. 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. FORECAST MAX TEMPS RANGE
FROM MID 40S SW TO UPPER 20S NE.

MAX TEMPS MONDAY THROUGH WEDNESDAY...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.

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 NEAR 50 F IN THE SW DVN
CWA TO THE MID 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. LOWER 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 AND REACH W IOWA BY THE LATE AFTN/EVENING.
THIS METEOROLOGICAL SETUP PUTS E IOWA AND W ILLINOIS IN THE WARM
SECTOR...1000-500 MB THICKNESS MAY PEAK AS HIGH AS 552 DAM AND 850
TEMPS NEAR +6 C WITHIN A S/SE SFC WIND FLOW.

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 THE ORIGINAL EAST COAST LOW INTO CENTRAL
CANADA. THIS MAY BE THE FIST SIGN OF A SIGNIFICANT PATTERN CHANGE TO
COLDER TEMPS...POSSIBLY COMMENCING NEXT WEEKEND.

FOR WHAT IT IS WORTH...BOTH THE GFS AND ECMWF HAVE 1000-500 MB
THICKNESS VALUES SUB-510 DAM BY NEXT SUN NIGHT/MON. IN LINE WITH
THIS RAW MODEL OUTPUT...THE CPC OUTLOOK FOR THE FIRST WEEK OF
FEBRUARY HAS A ~70% PROBABILITY FOR BELOW NORMAL TEMPS OVER E
IOWA/WESTERN ILLINOIS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 239 PM CST SAT JAN 24 2015

FAIR SKIES...VFR CONDITIONS WITH LIGHT WESTERLY WINDS THIS AFTERNOON
WILL GIVE WAY THIS EVENING TO BKN-OVC CLOUDS WITH CIGS AOA 6K AGL THROUGH
MIDNIGHT WITH ISOLATED TO SCATTERED LIGHT RAIN AND SNOW THAT IS HANDLED
AS A PROB30 GROUP BETWEEN 25/03-10Z AS A FAST MOVING CLIPPER SYSTEM
MOVES SOUTHEAST FROM THE DAKOTAS. BETWEEN 25/10Z AND 25/15Z AREAS OF
LIGHT TO MODERATE SNOW AND IFR CONDITIONS TO BE COMMON AS SURFACE LOW
MOVES SOUTHEAST INTO SE IOWA. WINDS WILL SHIFT TO THE NORTHEAST AT 10-20
KTS. CONDITIONS WILL BEGIN TO IMPROVE FROM NORTHWEST TO SOUTHEAST AFTER
25/17Z AS THE SNOW ENDS AND SKIES BEGIN TO CLEAR WITH VFR CONDITIONS
AT ALL TERMINALS BY 25/21Z.

&&

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

&&

$$

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






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