Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDVN 240952
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
352 AM CST TUE FEB 24 2015

.SYNOPSIS...
ISSUED AT 252 AM CST TUE FEB 24 2015

SOUTHWEST SURFACE WINDS HELPED KEEP OVERNIGHT TEMPERATURES STEADY
TO SLOWLY RISING ACROSS THE AREA. 3 AM TEMPERATURES WERE IN THE 6
TO 13 DEGREE RANGE ACROSS EASTERN IOWA AND NORTHWEST ILLINOIS.
SCATTERED MID AND HIGH LEVEL CLOUDS WERE STARTING TO MOVE INTO THE
AREA FROM THE NORTH.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 252 AM CST TUE FEB 24 2015

THE MAIN FORECAST ISSUE IN THE SHORT TERM PERIOD IS TEMPERATURES.
THE FORECAST FOR AFTERNOON HIGHS IS RATHER TRICKY DUE TO THE COMPETING
FACTORS OF STRONG SOUTHWEST WINDS AND INCREASING CLOUD COVER.
REVIEWING MESOSCALE MODEL LAYER RH PROGS...COMPARED TO UPSTREAM
CLOUD TRENDS...BELIEVE THE CLOUD COVER WILL BE WIDESPREAD ENOUGH TODAY
TO TEMPER THE LATE FEBRUARY INSOLATION. ON THE OTHER HAND...THE
CONSENSUS BLEND GUIDANCE HAS BEEN RUNNING A BIT TOO COOL...AND
WITH THE LOW LEVEL MIXING...I THINK IT`S REASONABLE TO GO 1-3
DEGREES ABOVE THE BLEND...ESPECIALLY SOUTH WHERE THERE IS LITTLE
OR NO LINGERING SNOW COVER. THIS YIELDS HIGHS NEAR 30 AT
FREEPORT...THEN WARMING INTO THE 35-38 DEGREE RANGE SOUTH OF U.S.
HIGHWAY 34. WITH THE PASSAGE OF THE SURFACE TROUGH TODAY...THERE
MAY BE SOME STRAY FLURRIES IN FAR NORTHWEST ILLINOIS...BUT NOTHING
OF SIGNIFICANCE. HIGH PRESSURE WILL BUILD INTO THE AREA
TONIGHT...WITH LOWS IN THE SINGLE DIGITS NORTH TO TEENS SOUTH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 252 AM CST TUE FEB 24 2015

WEDNESDAY...SFC LOW OVER SOUTHERN ALBERTA TUE MORNING WILL BE GUIDED
BY A WEAK BUT CONSISTENT COUPLED JET FEATURE AND WILL MOVE
SOUTHEASTWARD REACHING ROUGHLY SE NEBRASKA BY MIDDAY WED. THE LOW
WILL BRING A SWATH OF ACCUMULATING SNOW TO THE MIDWEST. THE EXACT
TRACK OF THE LOW IS IN QUESTION AND IS DEPENDENT ON THE POSITIONING
OF THE 850 MB BAROCLINIC ZONE.

TIMING...LOOKS LIKE SNOW WILL SPREAD INTO THE WESTERN CWA DURING THE
LATE MORNING OR EARLY AFTN ON WED AND EXIT THE EASTERN/SOUTHEASTERN
FORECAST AREA EARLY THU MORNING.

MODEL DISCREPANCIES...ECMWF/GEM/SREF PUSH THE SNOW SHIELD FURTHER TO
THE EAST AND NORTHEAST COMPARED TO THE NAM/GFS. 925-850
FRONTOGENESIS AND FN RESPONSE FIELDS KEEP THE STRONGEST ASSOCIATED
FORCING W/SW OF THE FORECAST AREA. HOWEVER...THE ECMWF FOR EXAMPLE
HAS STRONGER 850 MB CONVERGENCE MOVING ACROSS THE CWA ALONG WITH
MODERATE 300 MB DIVERGENCE UNDER THE JET ENTRANCE REGION.

POTENTIAL AMOUNTS...HIGHEST QPF AND SNOWFALL WILL OCCUR OVER THE
WESTERN/SOUTHWESTERN CWA. CURRENT FORECAST QPF IS BETWEEN 0.10-0.30
INCHES. USING A ~15:1 SLR PER COBB OUTPUT AND A FAVORABLE DENDRITIC
GROWTH ZONE OF +100 MB...YIELDS 2-4 INCHES OF SNOW WEST AND SOUTH OF
A CEDAR RAPIDS-TO-MACOMB LINE WITH A TRACE TO 2 INCHES TO THE EAST
(LIGHTEST NEAR THE WI BORDER).

STILL TIME FOR THE TRACK OF THIS SYSTEM TO SHIFT SO FORECAST MAY
CHANGE SOME BEFORE WED. THERE COULD BE A NARROW ZONE WHERE HIGHER
TOTALS OCCUR BUT NEED MORE CONSISTENT MODEL SOLUTIONS TO BE ABLE TO
DETERMINE IF THAT BAND WILL CROSS INTO THE DVN CWA FROM THE WEST.

THURSDAY AND FRIDAY...TEMPS DURING THIS PERIOD WILL BE CONTINGENT ON
HOW MUCH SNOW FALLS ON WEDNESDAY. RIGHT NOW HIGHS WILL GENERALLY BE
IN THE TEENS AND LOWS BELOW ZERO.

SATURDAY AND SUNDAY...SIGNIFICANT PATTERN CHANGE WILL OCCUR DURING
THIS TIME AS UPPER JET DIGS OUT A LARGE TROUGH OVER THE WESTERN U.S.
WHICH WILL CAUSE A BIG SHIFT IN THE ORIENTATION OF THE 850 MB
BAROCLINIC ZONE TO A SW-NE DIRECTION.

THERE HAS BEEN A CONSISTENT SIGNAL OF SIGNIFICANT LOW/MID LEVEL
MOISTURE ADVECTION FROM THE SW U.S. AND FROM THE GULF OF MEXICO FOR
SAT NIGHT INTO SUN. THEREFORE...A PERIOD OF SNOW IS LIKELY WITH
AMOUNTS UNCERTAIN THIS FAR OUT. WITH THE LACK OF A STRONG SHORTWAVE
TROUGH/VORTICITY MAX...MODELS DEVELOP LINEAR-LOOKING FRONTAL PRECIP
AND DO NOT DEVELOP A COHERENT SFC LOW WHICH WOULD PUT SOMEWHAT OF A
LIMIT ON THIS SYSTEM. DAYTIME TEMPS WILL BE IN THE 20S ON SAT AND
THE UPPER 20S TO MID 30S ON SUN.

MONDAY...CHANCE OF SNOW CONTINUES BUT MODELS STRUGGLE WITH WHEN TO
EJECT ORGANIZED 500 MB VORTICITY MAX OUT OF THE FOUR CORNERS AREA.
ECMWF HAS MORE OF A DEVELOPED SYSTEM ON MONDAY WHILE THE GFS IS DRY.
EITHER WAY BELOW AVG TEMPS EXPECTED WITH HIGHS IN THE MID 20S TO
LOWER 30S.

&&

.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...RP KINNEY
SHORT TERM...RP KINNEY
LONG TERM...UTTECH
AVIATION...NICHOLS





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.