Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Text Only | 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 272311
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
511 PM CST THU NOV 27 2014

.UPDATE...
ISSUED AT 508 PM CST THU NOV 27 2014

MANY 5 PM TEMPERATURES WERE ALREADY AT OR BELOW MINIMUM FORECAST
TEMPS...AND SHOULD CONTINUE TO FALL IN THE CLEAR CALM CONDITIONS
THROUGH MID TO LATE EVENING. LOWS HAVE BEEN LOWERED TO WIDESPREAD
SINGLE DIGITS. SOME FAVORED SITES MAY GO A BIT BELOW ZERO BY MID
EVENING.

&&

.SYNOPSIS...
ISSUED AT 345 PM CST THU NOV 27 2014

BRIGHT SUNNY AFTERNOON IN PROGRESS AS CANADIAN HIGH PRESSURE CONTINUES
TO BUILD INTO THE CWA FROM THE NORTHWEST. HOWEVER...LOOKS ARE DECEIVING
AS WE ARE EXPERIENCING THE COLDEST THANKSGIVING SINCE THE 1950S! 3 PM
READINGS WERE ONLY IN THE TEENS TO LOWER 20S ACROSS THE CWA AND IT
WAS EVEN COLDER TO OUR NORTHWEST...WITH TEMPERATURES STILL IN THE
SINGLE DIGITS IN NORTHERN IA...MN AND EASTERN DAKOTAS.

MEANWHILE...STRONG WARM AIR ADVECTION TO OUR WEST WAS PRODUCING
CLOUDS FROM THE DAKOTAS INTO WESTERN IA AND INTO CENTRAL MO AND
WERE MAKING SLOW PROGRESS TO THE EAST.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 345 PM CST THU NOV 27 2014

FORECAST FOCUS ON TEMPERATURES ALONG WITH A CHANCE OF LIGHT SNOW
AFTER MIDNIGHT.

TONIGHT...MOSTLY CLEAR SKIES NEAR SUNSET...ALONG WITH CALM TO
LIGHT WINDS AND SOME SNOW COVER...WILL ALLOW TEMPERATURES TO
REALLY PLUNGE QUICKLY. OF PARTICULAR CONCERN WILL BE PORTIONS OF
SOUTHEAST IA AND WESTERN IL THAT RECEIVED HEAVIER SNOWFALL YESTERDAY.
HOWEVER...WARM AIR ADVECTION CLOUDS WILL ALSO BE PROGRESSING EAST
INTO OUR FAR WESTERN CWA EARLY THIS EVENING AND SPREADING OVER ALL
THE CWA BY MIDNIGHT. WINDS WILL ALSO TURNING SOUTHEAST OVERNIGHT
AS THE HIGH PRESSURE RIDGE SHIFTS TO OUR EAST. THIS WILL ACTUALLY
CAUSE TEMPERATURES TO RISE DURING THE NIGHT AS STRONG WARM AIR
ADVECTION PUSHES ACROSS THE CWA. MINIMUM TEMPERATURES IN THE
SINGLE DIGITS AND TEENS WILL ACTUALLY OCCUR THIS EVENING.

IN ADDITION...ECMWF/NAM SATURATE THE COLUMN MAINLY NORTH OF INTERSTATE
80 AFTER MIDNIGHT DUE TO THE STRONG WARM AIR ADVECTION/FORCING.
CONDENSATION PRESSURE DEFICITS SUGGEST A BAND OF LIGHT SNOW PUSHING
ACROSS THE CWA LATE THIS EVENING AND OVERNIGHT...BUT THE BETTER
SATURATION/FORCING IS IN OUR NORTH. WILL INTRODUCE 30-40 POPS AFTER
MIDNIGHT AND THE C-DEFS SUGGEST A COUPLE OF HOURS OF POTENTIAL ACCUMULATING
SNOW. BECAUSE THE GFS IS DRY I DID NOT WANT TO GO LIKELY POPS BUT WILL
LET THE EVENING SHIFT MONITOR THE SITUATION. FOR NOW I BELIEVE ANY
ACCUMULATIONS WILL BE LESS THAN ONE-HALF INCH.

FRIDAY...ANY LINGERING LIGHT SNOW OR FLURRIES WILL END EARLY IN
THE MORNING IN OUR FAR NORTHEAST COUNTIES AS THE STRONG WARM AIR
ADVECTION SHIFTS INTO THE GREAT LAKES REGION. OTHERWISE WE GET
INTO THE WARM SECTOR WITH SOUTH WINDS RETURNING WARMER TEMPERATURES.
WILL CONTINUE TO FORECAST AFTERNOON TEMPERATURES RANGING FROM THE LOWER
30S ALONG HIGHWAY 20 TO THE LOWER 40S FAR SOUTH...BEGINNING THE MELTING
PROCESS ALL OVER AGAIN. HOWEVER...THE AREA OF SOUTHEAST IA INTO WESTERN IL
WHERE THE HEAVIER SNOW FELL YESTERDAY WILL PROBABLY BE SOMEWHAT COOLER
COMPARED TO SURROUNDING SITES.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 345 PM CST THU NOV 27 2014

FRIDAY NIGHT...NOT MUCH DROP IN TEMPS EXPECTED WITH CONTINUED WARM
ADVECTION. MAY SEE SOME PATCHY FOG WITH INITIAL MOISTURE
RETURN OVER COLD GROUND AND HAVE LEFT MENTION FROM PREVIOUS SHIFT.
NOT SURE THOUGH IF WE WILL SEE ENOUGH VISIBILITIES AT OR BELOW
1-2SM FOR MENTION ALTHOUGH COULD BE THE CASE OVER RESIDUAL SNOW
COVERED AREAS OF 2+ INCHES. IT COULD ALSO END UP SIMILAR TO LAST
WEEKEND WHEN IT WAS THE 2ND NIGHT OF MOISTURE RETURN RIGHT AHEAD OF
ARCTIC FRONT WHICH ENDED UP WITH WIDESPREAD DENSE FOG.

SATURDAY AND SATURDAY NIGHT...SATURDAY WILL SEE WARMUP PEAKING AS
SFC TO 850 MB THERMAL AXIS MOVES ACROSS CWA... WITH THE CHALLENGE
BEING JUST HOW WARM TO GO WITH COMPLEXITIES OF RESIDUAL SNOW
COVER AND ANY LINGERING FOG/STRATUS WHICH COULD BECOME TRAPPED
BENEATH INVERSION. 850 MB TEMPS ARE PROGGED IN RANGE OF 13-16C
OVER MUCH OF CWA AND WHILE THE BULK OF THIS WARMING WILL REMAIN
ALOFT GUSTY SOUTHWEST WINDS AND SOME MIXING GENERALLY SUPPORTIVE
OF UPPER 40S TO MIDDLE 50S. IF MORE SOLAR INSOLATION THEN COULD SEE
MORE WIDESPREAD 50S WITH SOME AREAS POSSIBLY NEAR 60F SOUTH IF LITTLE
TO NO SNOW COVER AND WITH DEEPER MIXING NEAR/ABOVE 925 MB. SATURDAY
NIGHT...AS MENTIONED THIS PERIOD MAY HARBOR BETTER FOG POTENTIAL OF
WHICH COULD BE DENSE WITH BRUNT OF MOISTURE ADVECTION AHEAD OF ARCTIC
FRONT. CANT ALSO RULE OUT SOME DRIZZLE AS WELL. TEMPS REMAINING MILD
WITH MUCH OF THE CWA STAYING IN THE PRE-FRONTAL WARM SECTOR MOST OF
THE NIGHT WITH THE FRONT MOVING INTO NORTHWEST CWA AROUND DAYBREAK
SUNDAY AM.

SUNDAY AND SUNDAY NIGHT...HIGHS ON SUNDAY WILL OCCUR DURING THE AM
THROUGH MIDDAY BEFORE PASSAGE OF ARCTIC FRONT IS FOLLOWED BY CRASHING
TEMPS ON BRISK NORTHWEST WINDS. MAY SEE SOME FLURRIES BEING WRUNG OUT
IN ARCTIC AIRMASS THROUGH SUNDAY NIGHT. TEMP DROPS OF 30-40+ DEGS
EXPECTED BETWEEN FCST HIGHS ON SATURDAY AND FCST LOWS SUNDAY
NIGHT... WHICH SEEMS FAIRLY COMMON PLACE OVER PAST SEVERAL WEEKS.
LOWS SUNDAY NIGHT ANTICIPATED AROUND 10 TO 20 DEGS WITH BITTER COLD
WIND CHILLS IN SINGLE DIGITS ABOVE AND BELOW ZERO BY 12Z MONDAY AM.

MONDAY AND MONDAY NIGHT...CANADIAN HIGH TO MAINTAIN COLD CONDITIONS
THROUGH THE PERIOD WITH TEMPS 15-20+ DEGS BELOW NORMAL. GENERALLY
DRY AS WELL ALTHOUGH FLURRIES MAY LINGER MONDAY. LOWS MONDAY NIGHT
IN THE SINGLE DIGITS AND TEENS.

TUESDAY THROUGH THURSDAY...UPPER LEVEL TROUGH PROGGED TO SWING THROUGH
THE MIDWEST INTO MIDWEEK MAINTAINING BELOW NORMAL TEMPS. STRENGTH OF
FORCING AND MAGNITUDE OF MOISTURE AT THIS TIME SUPPORT LIMITED
MEASURABLE PCPN POTENTIAL AND MAINLY FLURRIES... BUT THIS NEEDS TO BE
WATCHED FOR ANY STRENGTHENING WHICH WOULD NECESSITATE POPS. STILL
REMAINS CONSIDERABLE UNCERTAINTY AT AND JUST BEYOND THE SCOPE OF THE
EXTENDED. GFS HAS BEEN CONSISTENT PAST 4 RUNS WITH PCPN SIGNAL ON
THURSDAY IN STRONGER MOISTURE RETURN AHEAD OF EJECTING ROCKIES TROUGH.
MEANWHILE...ECMWF HAS BEEN CONSISTENTLY DRY BUT PAST 4-5 RUNS SHOW
MODEL VARYING QUITE A BIT WITH SURFACE AND UPPER LEVEL FEATURES. HAVE
TRIMMED POPS BUT MAINTAINED SLIGHT CHCS TO ACCOUNT FOR GFS POTENTIAL.
TEMPS ANTICIPATED TO MODERATE CLOSER TO NORMAL LATE WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 508 PM CST THU NOV 27 2014

CLEAR AND QUIET AVIATION WEATHER WILL LAST THROUGH TONIGHT...AS
CLOUDS INCREASE...BUT SNOW NOT LOOKS TO REMAIN NORTH OF EASTERN
IOWA TERMINALS. CIGS ABOVE 3000 FT ARE LIKELY OVERNIGHT AND
FRIDAY...WITH WINDS BECOMING SOUTHEAST ABOUND 10 KTS BY 10Z
FRIDAY.
ERVIN

&&

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

$$

UPDATE...ERVIN
SYNOPSIS...HAASE
SHORT TERM...HAASE
LONG TERM...05
AVIATION...ERVIN





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