704
FXUS63 KDVN 231100
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
500 AM CST SAT JAN 23 2021
..12Z AVIATION UPDATE
SYNOPSIS
ISSUED AT 341 AM CST SAT JAN 23 2021
A QUIET, BUT VERY COLD NIGHT WAS UNFOLDING ACROSS EASTERN IOWA,
NORTHWEST ILLINOIS AND NORTHEAST MISSOURI, AND WAS BROUGHT TO US BY
HIGH PRESSURE, ABUNDANT CLEAR SKIES AND LIGHT TO CALM WINDS.
TEMPERATURES AS OF 2 AM WERE MOSTLY IN THE SINGLE DIGITS CWA WIDE,
BUT SOME SPOTS WITH MORE ABUNDANT, FRESH SNOW COVER FOUND THEMSELVES
BELOW ZERO. SO FAR, THE COLD SPOT HAS BEEN MXO, WHICH HAS BEEN
SITTING AROUND FOUR BELOW ZERO FOR THE PAST FEW HOURS.
NOT FAR AWAY TO THE WEST, NIGHTTIME GOES-16 RGB WAS SHOWING
INCREASING CLOUD COVER OVER EASTERN NEBRASKA, FAR SOUTHWEST IOWA AND
NORTHWEST MISSOURI IN RESPONSE TO INCREASING MOISTURE AND WAA ACROSS
THE PLAINS. OVERTIME, THIS WILL WORK ITS WAY EAST, AND WILL IMPACT
OUR AREA THROUGH THE SHORT TERM PERIOD.
SHORT TERM
(TODAY THROUGH SUNDAY)
ISSUED AT 341 AM CST SAT JAN 23 2021
KEY MESSAGES:
1) SNOW DEVELOPS BY LATE AFTERNOON AND CONTINUES THROUGH TONIGHT, 1-
3 INCHES MAINLY NORTH OF HWY 30 EXPECTED.
2) LIGHT SNOW/FREEZING DRIZZLE CHANCES PERSIST THROUGH SUNDAY
MORNING, MAINLY DRY FOR THE REMAINDER OF THE DAY WITH CLOUDY SKIES.
OTHER THAN GRADUALLY INCREASING CLOUDS, MOST OF THE AREA WILL SEE A
QUIET DAY ON THE WEATHER FRONT AS THE SURFACE HIGH SLOW EXITS THE
AREA TO THE EAST. THIS HIGH WILL TAKE THE COLD AIR MASS WITH IT,
ALLOWING FOR SOUTHERLY FLOW ALOFT TO ADVECT SLIGHTLY WARMER
TEMPERATURES BACK INTO THE AREA. HIGHS SHOULD RANGE FROM NEAR 20
ALONG THE HWY 20 CORRIDOR, TO LOW 30S ALONG AND SOUTH OF HWY 34.
EARLY THIS AFTERNOON, OUR FIRST SHOT AT SOME PRECIPITATION SHOULD
BEGIN TO MAKE ITS WAY INTO OUR NORTHWEST CWA AS INCREASING LOW-LEVEL
WINDS BEGIN MOVING INTO THE AREA. GFS/NAM IN GOOD AGREEMENT OF 30-40
KT LLJ IN PLACE OVER CENTRAL IOWA BY MID-AFTERNOON, WHICH PUTS MUCH
OF NORTHEAST IOWA/SOUTHERN MINNESOTA IN A GOOD SPOT FOR SOME
INCREASED LIFT/FRONTOGENESIS. MOISTURE WITH THIS INITIAL SURGE OF
WINDS WILL BE MORE LACKING IN OUR AREA VS. AREAS TO OUR NORTHWEST AS
WE ARE CLOSER TO THE SURFACE HIGH, WHICH SHOULD HELP KEEP THE
HEAVIEST SNOWFALL WELL OUT OF THE AREA. FOR OUR CWA, EXPECT A
DUSTING TO A FEW TENTHS NORTH OF A WATERLOO TO DUBUQUE LINE.
MORE MOISTURE AND LIFT WILL ARRIVE ACROSS THE AREA LATER THIS
EVENING AND TONIGHT AS SOUTHERLY FLOW AHEAD OF A DEVELOPING SURFACE
LOW IN KANSAS INCREASES. FAVORABLE TEMPERATURES AND PLENTY OF ICE
FROM SEEDER CLOUDS ALOFT WILL ALLOW THE BULK OF PRECIPITATION TO BE
ALL SNOW FOR THE NIGHT, BUT AMOUNTS WILL BE LIMITED THANKS TO A
RELATIVELY SHALLOW AND NOT FULLY SATURATED DGZ. HOWEVER, DECREASING
CLOUD ICE LATE IN THE NIGHT COULD RESULT IN MORE OF A THREAT OF
FREEZING RAIN/DRIZZLE, BUT CONFIDENCE REMAINS LOW ON THIS BEING
WIDESPREAD.
SNOWFALL TOTALS WILL BE HIGHEST NORTH OF THE HWY 30 CORRIDOR, WHERE
1-3 INCHES IS EXPECTED THROUGH 6 AM SUNDAY. AMOUNTS WILL AROUND 1
INCH OR LESS TO THE SOUTH. DUE TO THE LOW EXPECTED TOTALS, KEPT WITH
THE THEME OF NO WINTER WEATHER ADVISORY WITH THIS FORECAST PACKAGE.
EXPECT A LULL IN WIDESPREAD PRECIPITATION SUNDAY, AS HIGH PRESSURE
ACROSS THE UPPER MISSISSIPPI VALLEY ATTEMPTS TO BUILD INTO THE AREA.
DESPITE THE HIGH, CLOUDS WILL BE PLENTIFUL AS THE LOW-LEVELS REMAIN
SATURATED. THIS WILL HELP KEEP TEMPERATURES THROUGH THE DAY IN THE
UPPER 20S TO LOW 30S, WITH THE HIGHER END OF VALUES FAVORED OVER
SOUTHEAST IOWA, WEST CENTRAL ILLINOIS AND NORTHEAST MISSOURI.
LONG TERM
(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 341 AM CST SAT JAN 23 2021
KEY MESSAGES:
1) INCREASING CONFIDENCE ON A STRONG WINTER STORM IMPACTING THE
REGION MONDAY INTO TUESDAY.
2) ACTIVE PATTERN TO PERSIST THROUGH THE END OF JANUARY.
SUNDAY NIGHT
LINGERING WEAK WARM ADVECTION SHOULD FOSTER POTENTIAL FOR
EXCEEDINGLY LIGHT PRECIPITATION ACROSS AREAS NEAR TO SOUTH
OF I-80. FORECAST SOUNDINGS SUGGEST POTENTIAL FOR LOSS OF
IN-CLOUD ICE, AND THEREFORE COULD BE FREEZING DRIZZLE ALONG
WITH SOME FLURRIES OR VERY LIGHT SNOW POSSIBLY. WILL HAVE TO
KEEP AN EYE ON ANY LIGHT GLAZING POTENTIAL AND IMPACTS TO
TRAVEL INTO THE MONDAY AM COMMUTE.
MONDAY-TUESDAY
CONFIDENCE IS INCREASING ON A STRONG WINTER STORM IMPACTING
THE REGION WITH POTENTIAL SIGNIFICANT TRAVEL IMPACTS DUE
TO HEAVY SNOW AND ALSO A WINTRY MIX POSSIBLE SOUTH. STILL
UNCERTAINTY IN THE EXACT TRACK, LOCATION OF THE HEAVIEST
PRECIPITATION AND AMOUNTS, BUT IF YOU ARE PLANNING ANY TRAVEL
DURING THIS TIME YOUR STRONGLY ENCOURAGED TO KEEP UPDATED ON
THE FORECAST AND PERHAPS EVEN CONSIDER DELAYING OR ADJUSTING
TRAVEL PLANS.
ATTENTION IS FOCUSED ON A SHORTWAVE EJECTING FROM THE GREAT BASIN.
STRONG UPPER LEVEL JET DIVERGENCE WILL AID CYCLOGENESIS IN THE
SOUTHERN PLAINS /OKLAHOMA/ LIFTING NORTHEAST INTO THE OHIO VALLEY.
NAM APPEARS TO BE AN OUTLIER IN QUICKLY DEAMPLIFYING THE
SHORTWAVE AND DISCOUNTED IN FAVOR OF BLEND OF GFS/ECMWF WITH
INPUTS FROM UKMET. GENERAL CONSENSUS OF THIS DETERMINISTIC BLEND
AND GFS/ECMWF ENSEMBLE MEANS FAVOR A MORE NORTHERLY TRACK OF THE
SURFACE LOW, ALBEIT STILL PASSING SOUTH OF OUR AREA. A BIT OF A
SLOWING TREND IN THE SYSTEM HAS ALSO BEEN OBSERVED IN THE
GUIDANCE. PRECIPITATION IS LIKELY TO OVERSPREAD MUCH OF THE AREA
AS MONDAY PROGRESSES FROM SOUTH TO NORTH, AND LINGERS TUESDAY
ALBEIT WEAKER. STILL SOME TIME FOR THE FINER DETAILS TO GET IRONED
OUT, BUT STRENGTH OF SYSTEM AND ANOMALOUSLY GULF MOISTURE FEED
PER NAEFS 3-4 STANDARD DEVIATIONS ON PWATS SUPPORT THE POTENTIAL
FOR A MODERATE TO HEAVY PRECIPITATION EVENT, WHICH WOULD LIKELY OFFER
SIGNIFICANT TRAVEL IMPACTS.
TIMING
THE PRECIPITATION IS LIKELY TO OVERSPREAD THE AREA FROM SOUTH
TO NORTH ON MONDAY AIDED BY UPPER LEVEL DIFFLUENCE AND
WAA/ISENTROPIC ASCENT WITHIN INCREASING GULF MOISTURE TAP INTO
SYSTEM. PEAK WOULD APPEAR TO BE MONDAY AFTERNOON/NIGHT BEFORE
SLOWLY DECREASING BUT LINGERING TUESDAY IN A SLOWLY WANING
DEFORMATION AXIS. MONDAY PM COMMUTE WOULD APPEAR TO HAVE GREATEST
IMPACTS, BUT LIKELY STILL AN IMPACT FOR THE TUESDAY AM COMMUTE AS WELL.
PRECIPITATION
THE INCREASING WAA/ISENTROPIC ASCENT WILL LIKELY DRIVE AN ELEVATED
WARM NOSE AT OR ABOVE 0C, WHICH COULD LEAD TO A WINTRY MIX
POTENTIAL INTO PORTIONS OF THE AREA MAINLY SOUTH OF I-80 ON MONDAY.
OTHERWISE, PREDOMINANTLY SNOW IS FAVORED OF WHICH COULD BE HEAVY
AT TIMES GIVEN THE STRENGTH OF FORCING AND WELL ABOVE NORMAL MOISTURE.
IT APPEARS THAT SEVERAL INCHES OF SNOW ARE LIKELY, WITH INCREASING
POTENTIAL FOR A BAND OF 6 INCHES OR MORE OF ACCUMULATION. STILL
UNCERTAINTY THOUGH ON PLACEMENT OF THIS BAND. THE SNOW IS LIKELY TO
BE PRIMARILY A WETTER/HEAVIER TYPE SNOW EARLY IN THE EVENT, BUT
BY LATE MONDAY NIGHT AND TUESDAY A TRANSITION TO A HIGHER SLRS AND A
FLUFFIER SNOW IS ANTICIPATED AS COLD ADVECTION INCREASES. SOME ICE
ACCUMULATION IS ALSO POSSIBLE SOUTH OF I-80, AND THIS APPEARS TO BE
LIGHT AT THIS TIME.
WINDS
NAEFS CONTINUES TO SUGGEST AN ANOMALOUSLY NORTHEAST JET COMPONENT
DEVELOPING WITH THIS SYSTEM, AS IT TRACKS TO OUR SOUTH. THUS,
HAVE BUMPED UP WINDS ESPECIALLY GUSTS BY MONDAY NIGHT THROUGH
TUESDAY WITH GUIDANCE INDICATING SOME POTENTIAL FOR 25-30+ MPH
GUSTS FROM E/NE. THIS COULD LEAD TO SOME BLOWING/DRIFTING POTENTIAL
BY MONDAY NIGHT THROUGH TUESDAY WITH A TRANSITION TO A FLUFFIER SNOW.
MIDWEEK AND BEYOND
WHILE A FAIR AMOUNT OF UNCERTAINTY EXISTS WITH THE NEXT SYSTEM,
THERE IS SEEMINGLY A GENERAL CONSENSUS SIGNAL FOR A WEAKER
SHORTWAVE AROUND THE WEDNESDAY TIMEFRAME. NBM POPS APPEARED TOO LOW
AS SEEMINGLY IT HAS STRUGGLED WITH LIGHTER QPF EVENTS OF LATE, AND
THUS HAVE COLLABORATED WITH NEIGHBORS TO BUMP UP INTO CHANCE POPS
FOR MAINLY SNOW. MAIN MESSAGE WITH THIS SYSTEM IS MUCH LOWER IMPACT
POTENTIAL WITH IT.
THE ACTIVE SOUTHWEST FLOW PATTERN LOOKS TO LINGER INTO NEXT WEEKEND,
AND WOULD OFFER SOME POTENTIAL FOR ANOTHER SYSTEM HEADING DEEPER INTO
NEXT WEEKEND. TEMPERATURES ALSO LOOK TO REBOUND, WITH THE EXTENT OF
ANY WARMUP PREDICATED ON EXTENT OF SNOW COVER.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 459 AM CST SAT JAN 23 2021
DEPARTING HIGH PRESSURE WILL KEEP VFR CONDITIONS IN PLACE ACROSS THE
AREA THROUGH MUCH OF THE DAYTIME TODAY. CALM WINDS AND CLEAR
SKIES WILL GIVE WAY TO INCREASING CLOUDS AND INCREASING SOUTHEAST
WINDS BY MIDDAY. BY LATE AFTERNOON, THERE IS POTENTIAL FOR BAND OF
MAINLY VFR SNOW TO IMPACT CID/DBQ. HOWEVER, PLENTIFUL DRY AIR IN
PLACE MAY LIMIT THIS, SO HAVE CHOSEN TO MAINTAIN THE PROB30 GROUP
FOR THIS TAF. HIGHER CONFIDENCE OF A WIDESPREAD SNOW ARRIVING
TONIGHT FOR ALL TERMINALS, WITH CONDITIONS DETERIORATING TO MVFR
WITH SPOTTY IFR POSSIBLE.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...SPECK
SHORT TERM...SPECK
LONG TERM...MCCLURE
AVIATION...SPECK
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page