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000
FXUS63 KDVN 301730 AAB
AFDDVN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1130 AM CST FRI JAN 30 2015

.UPDATE...
ISSUED AT 1049 AM CST FRI JAN 30 2015

MODELS HAVE CONFIRMED THE POTENTIAL FOR WIDESPREAD HEAVY SNOW AND
HAVE GONE OUT WITH A WINTER STORM WATCH FOR SATURDAY NIGHT THROUGH
SUNDAY AFTERNOON. THE NORTHWARD SHIFT IN THE AXIS OF HEAVY SNOW
BEGUN IN LAST NIGHT/S MODEL RUNS APPEARS TO BE CONFIRMED BY THE
NAM...AND TO A LESSER EXTENT THE GFS THIS MORNING. CANNOT RULE OUT
NEEDING ANOTHER TIER OF COUNTIES NORTH IN EAST CENTRAL IA.
THE ONSET TIME OF MEASURABLE SNOW MAY BEGIN A LITTLE EARLIER THAN
THE WATCH TIMING OVER OUR WESTERN COUNTIES SATURDAY AFTERNOON.
ALSO...HAZARDOUS CONDITIONS DUE TO BLOWING SNOW AND POSSIBLE
ADDITIONAL ACCUMULATIONS MAY CONTINUE INTO SUNDAY EVENING IN THE
EAST. OVERALL...WANTED TO REDUCE COMPLEXITY WITH A BROAD-BRUSH
APPROACH TO THE INITIAL WATCH ISSUANCE.

IN THE SHORT TERM...TWEAKS HAVE BEEN MADE TO THE FORECAST FOR
TODAY TO ADJUST SKY AND TEMPERATURE TRENDS.

&&

.SYNOPSIS...
ISSUED AT 252 AM CST FRI JAN 30 2015

SYNOPSIS...500 MB FLOW BECOMES ZONAL TODAY INTO SATURDAY MORNING AS
A MID-LEVEL VORTICITY MAX APPROACHES MONTANA AND A CUT-OFF LOW
SLIDES THROUGH THE SOUTHWEST U.S. INTO NW MEXICO. MOISTURE ADVECTION
AHEAD OF THE CUT-OFF LOW WILL INTERACT WITH THE NORTHERN STREAM
SHORTWAVE TO BRING WIDESPREAD PRECIP TO THE AREA LATER ON SATURDAY.
DRY CONDITIONS ARE FORECAST BEFORE THIS TIME WITH SEASONAL TEMPS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 252 AM CST FRI JAN 30 2015

TODAY...THE MORNING SHOULD START OUT WITH PARTLY TO MOSTLY SUNNY
CONDITIONS PER SIGNIFICANT CLEARING APPARENT ON THE 0845Z GOES IR
(3.9 MICRON) IMAGE. ALTHOUGH...MAY HAVE AN INCREASE IN MID-LEVEL
CIRRUS ACROSS NE THIRD OF THE FORECAST AREA FROM THE LATE MORNING
INTO THE AFTN. 500 MB RH PLOTS SHOW THIS FEATURE...CURRENTLY OVER S
MANITOBA/E NORTH DAKOTA/NW MINNESOTA...DROPPING IN FROM THE NW WITH
SATURATION BETWEEN 70-80%.

1000-500 MB THICKNESSES OF 528-534 DAM AND 850 MB TEMPS OF -4 TO -6
C WILL TRANSLATE INTO A SEASONAL LATE JANUARY DAY ACROSS E IOWA/W
ILLINOIS. FORECAST HIGHS RANGE FROM MID 30S SW OF BURLINGTON TO MID
20S NEAR DUBUQUE/FREEPORT. 1036 MB SFC HIGH WILL KEEP THE AREA DRY.

TONIGHT...SW RETURN FLOW AROUND THE SFC HIGH WILL ENSUE. PRIMARY
RESULT OF THIS WILL BE INCREASING MID-LEVEL CLOUDS AND THE
DEVELOPMENT OF STEADY BUT LIGHT SW WINDS AROUND 10 KTS. LOWS WILL BE
WARMEST OVER THE WEST IN THE MID 20S AND COOLEST OVER THE NORTHEAST
IN THE UPPER TEENS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 252 AM CST FRI JAN 30 2015

LONG TERM FORECAST CONFIDENCE ASSESSMENT...FAIR TO POOR OR AVERAGE TO
BELOW AVERAGE WITH WEEKEND QPF/SNOW TOTALS AND IMPACTS ON TEMPERATURES
BEYOND DAY 3 THE MAIN ISSUES. MOISTURE CONTINUITY...RUN TO RUN AND BOUNDARY
TOOLS AND SUGGEST TRACK A BIT TOO FAR NORTH AND AMOUNTS MOSTLY A BIT
TOO HIGH. PHASING ISSUE POORLY HANDLED AS NOT SAMPLED YET AND THIS WOULD
NEED TO OCCUR FOR SNOW TOTALS OF 6+ INCHES AND DAY SHIFT WILL BE ABLE
TO CONFIRM AS SW AND NW ENERGIES WILL BE IN THE UPPER AIR NETWORK. IF
AREA RECEIVES WIDESPREAD 4+ INCH AMOUNTS THEN TEMPERATURES REST OF NEXT
WEEK ARE LIKELY TOO MILD BY 5 OR MORE DEGREES IN MANY PERIODS...ESPECIALLY
LOWS WITH LIGHT WINDS AND FAIR SKIES.

OVERVIEW...INITIALIZATION AND VERIFICATION IS FAIR TO POOR WITH SOUTHERN
PLAINS BL MOISTURE OVERDONE BY SEVERAL DEGREES ON SURFACE DEWPOINTS.
RUN TO RUN VERIFICATION SUPPORTS A 70/30 MIX OF GFS WITH GEM-NH WITH
HI-RES ECMWF 20-30 PERCENT TOO HIGH ON QPF AMOUNTS AND TOO FAR NW.

SATURDAY...AREAS OF RAIN AND SNOW TO OVERSPREAD THE REGION WITH EVAPORATIVE
COOLING TO CONVERT ALL PRECIPITATION TO SNOW WITH SUSTAINED FORCING
AS COLUMN COOLS. LATER SHIFTS MAY BE ABLE TO CHANGE AREAS THAT HAVE
LIKELY TO CATEGORICAL POPS TO JUST SNOW DUE TO THE EVAPORATIVE COOLING.
HIGHS OF 35 TO 40 ARE DEPENDING ON PRECIPITATION ARRIVING LATER IN THE
DAY.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...PHASING OF SW AND NW ENERGY SUGGEST
PERIODS OF LIGHT TO MODERATE SNOW WITH 12-15 TO 1 RATIOS. LOCAL TOOLS
BASED ON MOISTURE BUDGET THAT IS SLIGHTLY LOWER THAN BLENDED GUIDANCE
SUPPORTS AREAS OF 4 TO 6+ INCH AMOUNTS WITH RISK OF 8 INCHES. UPPER
ENERGY AND JET ANALYSIS SUGGEST SOUTHERN 1/2 OF AREA CURRENTLY PREFERRED
TO SEE HIGHEST AMOUNTS WITH 2-4 INCHES NORTH OF HIGHWAY 30 CORRIDOR.
AGAIN THE PHASING OF THE ENERGY FROM THE NORTH AND SOUTH SHOULD BE
BETTER KNOWN TODAY AND WILL PASS THE DECISION ON ANY HEADLINE TO DAY
SHIFT. AT THIS TIME...AXIS OF HEAVIEST SNOWS +/- 40 NM EITHER SIDE
OF A OTM-MUS-VYS AXIS. MINS SATURDAY NIGHT SHOULD BE ON WARM SIDE
OF GUIDANCE WITH NEARLY STEADY TEMPERATURES ON SUNDAY AS NORTH WINDS
INCREASE TO 15 TO 25+ MPH. MINS MONDAY AM IN SINGLE DIGITS ARE DEPENDENT
OF SNOW ENDING BY MIDNIGHT WITH CLEARING SKIES.

MONDAY THROUGH THURSDAY...GENERALLY DRY WITH SOME LIGHT SNOW LATE TUESDAY
INTO WEDNESDAY AND BELOW NORMAL TEMPERATURES. DECENT SNOW PACK SUGGEST
LATER SHIFTS WILL NEED TO TRIM TEMPERATURES MOST PERIODS BY 2 TO 5 DEGREES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1124 AM CST FRI JAN 30 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD WITH NO PRECIP AT
THE TAF SITES. AN APPROACHING WINTER STORM SHOULD STAY OUT OF THE
AREA THROUGH THE PERIOD. THERE IS A SLIGHT CHANCE THAT BRL COULD
SEE SOME -RA AROUND 18Z ON SATURDAY. CU CLOUDS COULD DEVELOP TODAY
IN THE MVFR CEILING HEIGHT RANGE...HOWEVER DO NOT EXPECT ANY CEILING
ISSUES.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
     AFTERNOON FOR CEDAR-CLINTON-DES MOINES-HENRY IA-IOWA-
     JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA-MUSCATINE-SCOTT-VAN
     BUREN-WASHINGTON.

IL...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
     AFTERNOON FOR BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-
     MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-WARREN-WHITESIDE.

MO...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
     AFTERNOON FOR CLARK-SCOTLAND.

&&

$$

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