Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 260540
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1140 PM CST WED FEB 25 2015

.UPDATE...
ISSUED AT 1139 PM CST WED FEB 25 2015

CONDITIONS CONTINUE TO IMPROVE ACROSS THE NORTHERN HALF OF THE
FORECAST AREA...WHILE LIGHT SNOW CONTINUES CENTRAL AND SOUTH.
ANOTHER WEAK MID LEVEL SHORTWAVE EMBEDDED IN THE CYCLONIC NW FLOW
ALOFT MOVING THROUGH CENTRAL IA APPEARS TO BE REINVIGORATING THE BANDS
OF SNOW OVER SE INTO FAR E CENTRAL IA. AT THE SAME TIME...THE
LOW LEVEL FLOW CONTINUES TO BECOMING INCREASINGLY MORE ANTICYCLONIC
WITH THE PASSING SURFACE LOW NOW OVER S CENTRAL MO. ADDITIONAL
LIGHT SNOW ACCUMULATIONS...MOST LIKELY LESS THAN AN INCH STILL
LOOK POSSIBLE SOUTH OF I-80 AND ESPECIALLY ALONG THE HIGHWAY 34
CORRIDOR AND WILL CONTINUE THE PROCESS OF EXPIRING THE REMAINING
PORTIONS OF THE WINTER STORM WARNING OVER SE IA AND ADJACENT
ADVISORY AS UPDATED EARLIER THIS EVENING.

&&

.SHORT TERM...(THIS EVENING AND OVERNIGHT)
ISSUED AT 334 PM CST WED FEB 25 2015

WATCHING UPSTREAM TRENDS...CONCEPTUAL FORCING....SEVERAL HIRES
SOLUTION ELEVATED WARM AIR CONVERGENT WINDS PIVOTING AROUND THE
CLIPPER AND ISENTROPIC LIFT/SATURATION PROGS USING 290-295K
LAYER... SEEMS EARLIER THOUGHTS OF STRONGER BANDED FORCING
DROPPING ALONG AND WEST OF THE DVN CWA THROUGH LATE EVENING. BUT
EASTERN THRONG OF THIS LIFT SPOKE/NOW EXTENDING FROM DBQ WESTWARD
ALONG HWY 20 THEN DIPPING TOWARD DSM STILL TO IMPACT THE WESTERN
2/3S OF THE CWA THROUGH TONIGHT. STILL EXPECT SOME 1 INCH/HR RATES
UNDER THIS BAND AS IT PIVOTS SOUTH-SOUTHEASTWARD THRU THESE AREAS
LATE AFTERNOON AND INTO THE EVENING. BUT SEVERAL PROGS WEAKEN IT
AS IT SEEPS SOUTHWARD ESPECIALLY ALONG AND SOUTH OF I80 FROM 6 PM
THROUGH 10-11 PM. THIS MAY MAKE THE SOUTHERN PORTION OF THE
WARNING AREA MARGINAL AN MORE IN THE WAY OF 5-6 INCHES BY THE TIME
IT TAPERS TO FLURRIES OR LIGHT SNOW LATE TONIGHT. THE LATEST HRRR
SAYS DOWN TO FLURRIES OR LIGHT SNOW WITH LITTLE ADDITIONAL ACCUMS
BY 11 PM SOUTH OF I80. THIS MAY BE A LITTLE PROGRESSIVE TAKING
INTO ACCOUNT THE CLIPPER/S SLOWING INTERACTION WITH THE STRONG
LOWER MS RVR VALLEY WAVE...BUT WILL ONLY ADVERTISE HALF INCH TO
NEAR AN INCH SOUTH OF I80 AFTER 11 PM. BULK OF SNOW ACCUMS TO
OCCUR FROM 1 TO 2 HRS AGO...THROUGH 10 PM THIS EVENING FROM NORTH-
TO-SOUTH.

LATEST THINKING/SNOW AMOUNTS THAT WILL BE ADVERTISED TAKES INTO
ACCOUNT QUITE A DELAY FOR LLVL SATURATION TO OCCUR AND SNOW TO REACH
THE SFC TODAY...AND MUCH OF THE INITIAL LIFT SURGE GOING INTO THIS
SATURATION PROCESS/OVERCOMING DRY LLVL NORTHEASTERLY FLOW WHICH IS
STRONGER THAN WHAT THE EARLIER MODELS PREDICTED. WILL ACTUALLY BE
ABLE TO KEEP ONGOING WARNING AND ADVISORY HEADLINES FOR THE COUNTIES
WHICH THEY COVER NOW...BUT TRIM BACK THE SNOW TOTALS. EASTERN HALF
OF THE ADVISORY AREAS MAY BE MORE IN THE WAY OF 2-4 INCHES AND
WESTERN PORTIONS MORE IN THE WAY OF 3-5 INCHES. WARNING AREAS MORE
WIDESPREAD 4-7 INCHES WITH AN ISOLATED 8 INCH AMOUNTS POSSIBLE. STILL
SOME CONCERN WITH THE WAVE ACRS THE LOWER MS RVR VALLEY A BIT FURTHER
SOUTH THAN WHAT THE MODELS INDICATED YESTERDAY...IT WILL HAVE A LESS
OF A BLOCKING/STALLING EFFECT ON OUR PASSING CLIPPER ALLOWING IT TO
BE MORE PROGRESSIVE AND THUS SHORTER SNOWFALL DURATION. THIS MAY BE
WHAT THE LATEST HIRES AND 18Z RUN SOLUTIONS PICKING UP ON WITH AN
EARLIER EXIT. THUS ADVERTISED SNOWFALL AMOUNTS MAY BE STILL A BIT
TOO HIGH IN SOME AREAS IF THIS PROCESS VERIFIES. LOWS TONIGHT
DIPPING INTO THE LOW SINGLE DIGITS IN THE NORTH...TO THE LOWER TEENS
IN THE FAR SOUTHEAST. AGAIN...AND EARLIER SYSTEM EXIT AND SOME
CLEARING IN THE NORTH TOWARD SUNRISE...TEMPS MAY GET COLDER IN THE
NORTH THAN ADVERTISED.     ..12..

.LONG TERM...(THURSDAY THROUGH NEXT WEDNESDAY)
ISSUED AT 334 PM CST WED FEB 25 2015

FORECAST FOCUS ON AN ACTIVE WINTRY PATTERN ALONG WITH BRUTALLY COLD
TEMPERATURES FOR LATE FEBRUARY. MARCH TO ARRIVE LIKE A LION BUT WITH
TEMPERATURES NOT AS COLD.

THURSDAY...WILL WALK OUT THIS EVENT IN OUR SOUTHEAST COUNTIES IN THE
MORNING. ANY ADDITIONAL ACCUMULATIONS WILL BE LESS THAN 1/2 INCH.
MAXIMUM TEMPERATURES WILL BE IN THE SINGLE DIGITS NW TO THE TEENS SE.

THURSDAY NIGHT AND FRIDAY...RECORD BREAKING COLD EXPECTED DUE TO THE
FRESH SNOW PACK AND ARCTIC HIGH PRESSURE SETTLING OVER THE REGION.
TIME HEIGHT SECTIONS INDICATE DECENT SUBSIDENCE WHICH WILL PROVIDE
CLEAR SKIES AND RATHER LIGHT WINDS. 850 MB TEMPERATURES DROP TO
ABOUT -20 TO -22C OVER THE CWA. WITH A FRESH SNOW COVER THIS WILL
ALLOW MINIMUM TEMPERATURES TO PLUMMET TO 9 TO 16 BELOW ZERO. RECORD
LOWS FOR FEBRUARY 27 ARE IN JEOPARDY AT ALL CLIMATE SITES...SOME
DATING BACK TO 1879! IN ADDITION...UNLESS WINDS GO TOTALLY CALM FOR
THURSDAY NIGHT THEN WE WILL BE DEALING WITH POTENTIAL FOR WIND CHILL
WARNING CRITERIA...ESPECIALLY ALONG AND NORTH OF INTERSTATE 80.
OTHERWISE THIS CERTAINLY LOOKS TO BE AT LEAST A SOLID ADVISORY OF 20
TO 30 BELOW ACROSS THE ENTIRE CWA. VERY COLD BUT SUNNY ON FRIDAY
WITH HIGH TEMPERATURES ONLY IN THE 8 TO 12 ABOVE RANGE.

FRIDAY NIGHT...ANOTHER VERY COLD NIGHT WITH MINIMUM TEMPERATURES
DROPPING TO 5 TO 13 BELOW ZERO. WIND CHILLS SHOULD DROP TO 20 TO 30
BELOW ZERO ONCE AGAIN AS THE SURFACE HIGH SHIFTS EAST AND WINDS PICK
UP SOME. ANOTHER WIND CHILL HEADLINE WOULD BE NEEDED. THERE IS ALSO
THE POTENTIAL FOR RECORD LOWS FOR FEBRUARY 28.

THIS WEEKEND...NEXT IN THE HIT PARADE IS ANOTHER SIGNIFICANT WINTER
STORM ARRIVING OUT OF THE SOUTHWEST TROUGH. THIS WILL BEGIN TO PULL
MOISTURE FROM THE WESTERN GULF OF MEXICO SO THERE IS THE POTENTIAL
FOR SIGNIFICANT SNOW ACCUMULATIONS...BUT TOO EARLY FOR DETAILS. AT
THIS POINT THE MORE WIDESPREAD/HEAVIER SNOW SHOULD OCCUR SATURDAY
NIGHT INTO SUNDAY MORNING. ECMWF/GFS EERILY SIMILAR IN REGARDS TO
THIS SYSTEM. HIGH TEMPERATURES ARE EXPECTED TO PUSH INTO THE TEENS
TO LOWER 20S SATURDAY AND THEN MID 20S TO LOWER 30S ON SUNDAY.

MONDAY THROUGH WEDNESDAY...OPERATIONAL MODELS ALSO SIMILAR IN
DEPICTING YET ANOTHER SIGNIFICANT WINTER STORM AROUND THE MONDAY
NIGHT AND TUESDAY TIME FRAME. EVEN A DEEPER SOUTHWEST FLOW SHOULD
ALLOW DEEPER GULF MOISTURE TO BE TRANSPORTED NORTHWARD. HOWEVER...
QUITE A DIFFERENCE IN THERMAL PROFILES WITH THE ECMWF SUGGESTING ALL
SNOW WHILE THE GFS INTRODUCES THE THREAT OF MIXED PRECIPITATION.
WITH AN EVEN DEEPER SNOW PACK I WOULD THINK THE MORE SOUTHERN ROUTE
WOULD APPLY THUS FAVORING THE COLDER ECMWF. WITH THE PASSAGE OF THAT
SYSTEM THE NORTHWEST FLOW/ARCTIC AIR IS POISED TO RETURN BY MID/LATE
NEXT WEEK.

HAASE

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1139 PM CST WED FEB 25 2015

OUTSIDE A FEW FLURRIES...SNOW HAS ENDED AT CID AND DBQ AND VFR
CONDITIONS ARE EXPECTED TO PREVAIL THERE THROUGH THE ENTIRE TAF
CYCLE. AT MLI AND BRL...MVFR AND PERIODS OF IFR ARE EXPECTED
OVERNIGHT AS THE BACK EDGE OF SNOW WITH A DEPARTING WINTER STORM
SYSTEM RETREATS TO THE SOUTHEAST. FORECAST MODELS APPEAR TO BE TOO
AGGRESSIVE WITH LOW CLOUDS AND MVFR CIGS OVER MUCH OF EASTERN IA INTO
THURSDAY MORNING...AND HAVE INSTEAD KEPT CONDITIONS VFR. A COLD
HIGH PRESSURE SYSTEM MOVING IN FROM THE NORTHERN PLAINS THURSDAY
WILL RESULT IN DIMINISHING NW WINDS AND MOSTLY CLEAR SKIES BY
THURSDAY NIGHT.

&&

.CLIMATE...

RECORD LOWS FOR FEBRUARY 27...

MOLINE.........-12 IN 1934
CEDAR RAPIDS...-10 IN 1897
DUBUQUE........-12 IN 1879
BURLINGTON.....-7 IN 1934

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WARNING UNTIL 3 AM CST THURSDAY FOR DES MOINES-
     HENRY IA-JEFFERSON-LEE-VAN BUREN.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR CLINTON-
     SCOTT.

     WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR CEDAR-LOUISA-
     MUSCATINE.

IL...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ROCK
     ISLAND.

     WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR HANCOCK-
     HENDERSON-MCDONOUGH-WARREN.

     WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR HENRY IL-
     MERCER.

MO...WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR CLARK-
     SCOTLAND.

&&

$$

UPDATE...SHEETS
SHORT TERM...12
LONG TERM...HAASE
AVIATION...SHEETS
CLIMATE...HAASE





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