Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 231152
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
552 AM CST FRI JAN 23 2015

.SYNOPSIS...
ISSUED AT 326 AM CST FRI JAN 23 2015

LATEST SFC ANALYSIS WAS INDICATING ELONGATED RIDGE COMPLEX ACRS THE
CENTRAL PLAINS...UP ACRS MUCH OF IL/IND/OH...WHILE TROFFINESS ACRS
THE NORTHERN PLAINS WAS TIGHTENING SOUTH-SOUTHWESTERLY RETURN FLOW
ACRS THE UPPER MS RVR VALLEY. STUBBORN SLOW MOVING STRATOCU DECK
EDGING EASTWARD STARTING TO MAKE SOME MORE HEADWAY...WITH CURRENT
EXTRAPOLATION PUTTING IT/THE WESTERN CLEARING EDGE GENERALLY ALONG
THE MS RVR BY 8-830 AM CST OR SO. TEMPS UNDER IT HELD IN THE UPPER
20S TO AROUND 30...WHILE AREAS THAT CLEAR BEFORE SUNRISE DIP INTO THE
LOWER 20S OR EVEN UPPER TEENS. ALOFT...THE CURRENT WATER VAPOR
IMAGERY LOOP WAS INDICATING THE MAIN WAVE IN THE NORTHERN STREAM
PUSHING EAST-SOUTHEAST OF THE LK WINNIPEG REGION OF CANADA...WITH
SECONDARY VORT MAX TAILING DOWN ACRS THE DAKOTAS ATTM.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CST FRI JAN 23 2015

TODAY...WILL BANK ON THE CLOUDS KEEPING THERE EASTWARD MOVEMENT AND
POSSIBLY ACCELERATING AFTER SUNRISE AND AS LLVL SOUTHWESTERLY FLOW
INCREASES THIS MORNING. BUT WILL LINGER THE DECK ACRS THE FAR
EASTERN CWA THROUGH THE MID-LATE MORNING PER SOME OF THE HIRES LLVL
RH PROGS HAVE PICKED UP UPON THE SLOWER PROGRESSION AND DELAYED
INCREASE IN THE LLVL SOUTHWESTERLIES ACRS THE EAST HALF OF IL UNTIL
THEN. THEN AS THE MAIN CANADIAN WAVE TAKES AIM AND DIGS TOWARD THE
NORTHEASTERN GRT LKS/SOUTHEASTERN JAMES BAY REGION BY THIS EVENING...
THE CWA WILL BECOME INCREASINGLY IN THE WARM SECTOR OF THIS SYSTEM.
EVEN CONSERVATIVE MIXING UP TO 925 MB SUPPORTS WIDESPREAD HIGHS IN
THE UPPER 30S TO LOWER 40S...WITH SOME AREAS IN THE SOUTH POSSIBLY
PUSHING THE MID 40S. WILL SIDE WITH THE MILDER MAV GUIDANCE HIGHS OR
EVEN GO A DEGREE OR TWO WARMER AWAY FROM SNOW COVER ACRS FAR NE
IA/NW IL. THE UPSTREAM SFC TROF AND VORT LOBE CURRENTLY ACRS THE
DAKOTAS WILL PUSH DOWN AND ALMOST BI-SECT IA FROM NE-TO-SW BY THIS
EVENING. EXPECT AN INCREASE IN AC FROM THE NORTHWEST THIS AFTERNOON
INTO THE EVENING AS THESE FEATURES APPROACH. A LOW CHC OF SOME SCTRD
SPRINKLES GETTING KICKED UP BY THE APPROACHING VORT MAX TO MAKE IT
INTO THE NORTHWEST AND THEN NORTHERN CWA GENERALLY ALONG AND NORTH OF
THE HWY 30 CORRIDOR LATE THIS AFTERNOON AND THEN INTO THE MID EVENING
PERIOD...BUT SOUNDING SUGGEST SUCH DRY LOW TO MID LEVELS TO OVERCOME
THAT WILL NOT MENTION ANY PRECIP ARRIVAL AT THE SFC IN THESE AREAS
AND THAT THERE MAY BE JUST SOME SPOTTY VIRGA IF ANYTHING.

TONIGHT...PASSING TROF AXIS DURING THE EVENING TO VEER WIND PROFILES
TO THE NORTHWEST BY MIDNIGHT...WITH A LATE NIGHT INCREASE ALONG WITH
SOME COOLER AIR DRAW/COLD AIR ADVECTION...H85 MB NORTHWEST FLOW WILL
LOOK TO INCREASE TO 25-30 KTS BY 10Z-12Z SAT ACRS MUCH OF THE AREA.
CLOUD COVER WILL CONTINUE TO INCREASE ALONG AND POST-TROF PASSAGE
ESPECIALLY ACRS THE NORTHERN TWO THIRDS OF THE CWA. SFC TEMPS WILL BE
HELD UP THROUGH MID EVENING UNTIL THE TROF PASSAGE...WITH LOWS MAKING
IT INTO THE UPPER 20S TO AROUND 30 BY SUNRISE SAT. FCST SOUNDINGS
TOP-DOWN DRY AFTER THE TROF PASSAGE...WITH JUST A LOW DECK POSSIBLE
UNDER H9 MB NORTH OF I80 AFTER 06Z SAT AND INTO SAT MORNING. SOME
QUESTION IF THE NAM/GFS AGAIN ARE OVERDOING THIS LLVL MOISTURE AND IF
IT WILL REALLY BE DEEP ENOUGH TO POSSIBLY SUPPORT SOME SPOTTY DRIZZLE
OR FREEZING DRIZZLE DEPENDING ON SFC TEMPS...BREAKING OUT IF ANY LIFT
PERSISTS LATE TONIGHT. WITH THE UNCERTAINTY IN THESE DRIZZLE
PROFILES IN THE FCST SOUNDINGS...AS WELL AS THINKING MUCH OF THE LIFT
INDUCED BY THE PASSING VORT/OR VORTS/ WILL BE EAST OF THE AREA BY THE
TIME THE SOUNDINGS GO TO DRIZZLE PROFILES...WILL KEEP OUT MENTION FOR
NOW AND PASS ALONG ANY CONCERNS TO THE DAY-SHIFT.   ..12..

.LONG TERM...(SATURDAY THROUGH NEXT THURSDAY)
ISSUED AT 326 AM CST FRI JAN 23 2015

THE LONG TERM FORECAST IS GENERALLY BENIGN...WITH THE EXCEPTION OF
SATURDAY NIGHT AND SUNDAY...WHEN A PROBLEMATIC CLIPPER IS FORECAST TO
IMPACT THE UPPER MIDWEST. MODELS ARE HIGHLY VARIABLE ON THE TRACK
AND STRENGTH OF THIS CLIPPER...AND SINCE THE SHORT WAVE IS JUST NOW
MAKING IT ON SHORE IN BRITISH COLUMBIA...THIS WIDESPREAD OF MODEL
DATA REALLY PUTS A DAMPER ON ANY CONFIDENCE.

THE MODELS SHOW ANYTHING FROM A ALL SNOW EVENT...TO ONE MAINLY
DRY...WITH ONLY RAIN IN THE FAR NORTHEAST. THE NAM IS THE FARTHEST
NORTHEAST WITH THE TRACK OF THE LOW INTO WISCONSIN...WHILE THE 00Z
ECMWF REMAINS THE FARTHEST OPERATION MODEL SOUTHWEST...WITH A TRACK
THROUGH SOUTHEAST IOWA. I DO THINK THE LOW IS LIKELY TO BE FARTHER
NORTHEAST THAN THE EC TRACK...AS THERE IS NO SNOW COVER SOUTHWEST OF
DUBUQUE...AND SIGNIFICANT LOW LEVEL WAA SHOULD LIMIT ANY SNOW IN THE
SOUTHERN 2/3RDS WITH THIS SYSTEM. AS IT THE CASE WITH NEARLY ALL
CLIPPERS...THE SNOW WILL FALL TO THE LEFT OF THE SURFACE LOW IN A
PERIOD OF WAA/DYNAMIC LIFT OVERLAP. SINCE THE BLENDED SOLUTIONS TAKE
THE SURFACE LOW THROUGH OUR NORTHEAST...I WILL INCREASE TO HIGH
CHANCE TO LOW LIKELY THERE FOR LATE SATURDAY NIGHT AND SUNDAY...BUT
KEEP LOWER TO MID CHANCE GOING ELSEWHERE. IN THE END...SHOULD THE
NAM DRY AND WARM SOLUTION VERIFY...WE CAN DROP POPS MORE
SIGNIFICANTLY IN THE SOUTHWEST HALF...AND RAISE TEMPERATURES. WITH
LOW LEVELS IN THE UPPER 30S TO MID 40S...I HAVE THAT AREA GETTING
RAIN ANYWAY...WHERE AS THE NORTHEAST TIP SHOULD BE MAINLY SNOW OR
RAIN/SNOW MIX. WITH THE MARGINAL PTYPE...AND MARGINAL LOW LEVEL
TEMPERATURES...IT APPEARS SNOW SHOULD BE LIMITED TO ONLY THE NORTH
AND AMOUNTS AROUND 1 INCH SEEM ON TARGET.

LOOKING BEYOND...CAA WILL BRUSH THE AREA SUNDAY NIGHT THROUGH
TUESDAY...WITH ANOTHER WEAK CLIPPER TYPE EVENT MONDAY AFTERNOON AND
NIGHT. WE WILL CARRY 20 POPS FOR THIS EVENT. AMOUNTS UNDER 1 INCH
ARE EXPECTED IF IT MEASURES AT ALL. TUESDAY AFTERNOON THROUGH
THURSDAY THE UPPER FLOW CLIPPER TRACK IN NORTHWEST FLOW SHOULD
SHIFT WELL TO OUR NORTH. THIS PLACES OUR REGION INTO STRONG WAA AND
WEAK COLD FROPA EVENTS THROUGH AT LEAST FRIDAY. THIS WILL MELT ANY
SNOW THAT REMAINS OVER THE CWA...AND SHOULD PUT US ON TRACK FOR
SEVERAL DAYS NEAR OR ABOVE 40 IN THE ENTIRE CWA. NO DOUBT...JANUARY
WILL BE GOING OUT LIKE A SLIGHTLY MUDDY LAMB.
ERVIN

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 539 AM CST FRI JAN 23 2015

MVFR STRATOCU DECK MOVING EASTWARD AND WILL CLEAR THE MS RVR BY
AROUND 14Z OR SO...THEN A MAINLY VFR DAY WITH INCREASING
SOUTHWESTERLY SFC WINDS OF 8-15KTS. THE HIGHER WINDS TO OCCUR MAINLY
FROM I80 NORTHWARD IN TIGHTER PRESSURE GRADIENT AHEAD OF
APPROACHING FRONTAL SYSTEM FROM THE NORTHWEST. HIGH AND MID CLOUDS
WILL INCREASE AGAIN FROM THE NORTHWEST THIS AFTERNOON AND INTO
THE EVENING BUT ARE EXPECTED TO REMAIN AT VFR LEVELS. A LOW CHC
FOR A LIGHT SHOWER OR SPRINKLE IN THE VCNTY OF CID AND DBQ LATER
THIS AFTERNOON AND INTO THE EVENING...BUT WITH DRY AIR IN THE
LOWER LEVELS OF THE ATMOSPHERE ANY PRECIP WILL LIKELY REMAIN ALOFT
OR TO THE NORTH OF THE TERMINALS AND WILL NOT MENTION. PASSING
FRONT WILL VEER THE SFC WINDS TO THE WEST AND DECREASE SOME DURING
THE EVENING...THEN CONTINUE TO VEER TO THE NORTHWEST AFTER MIDNIGHT
AND INCREASE TO AROUND 10 KTS. SOME OF THE MODELS WANT TO BRING A
LOWER DECK/MVFR OR EVEN IFR LEVEL CLOUDS ACRS THE TERMINALS LATE
TONIGHT BUT THINK THEY MAY BE TOO MOIST TOO LOW AND WILL MAINTAIN
VFR EXCEPT FOR AT DBQ WHICH WILL HAVE THE BEST CHC FOR MVFR.  ..12..

&&

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

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...ERVIN
AVIATION...12





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