409
FXUS63 KDVN 261206
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
706 AM CDT TUE MAR 26 2019
..AVIATION UPDATE
SYNOPSIS
ISSUED AT 330 AM CDT TUE MAR 26 2019
HIGH PRESSURE IS NOW OVER THE GREAT LAKES, WITH LIGHT EASTERLY FLOW
TO SOUTHEASTERLY FLOW BECOMING ESTABLISHED OVER IOWA AND ILLINOIS.
THIS IS SERVING TO PUSH THE LINGERING MID CLOUDS A BIT WEST AND THIN
THE AXIS AS WELL. IN ALL, DESPITE SOME CIRRUS SPILLING OVER THE
RIDGE ALOFT, SKIES ARE FINALLY ENTERING INTO A MORE WIDESPREAD CLEAR
STATUS.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 330 AM CDT TUE MAR 26 2019
BENIGN WEATHER IS IN STORE TODAY WITH HIGH PRESSURE IN CONTROL.
LIGHT SOUTHEAST WINDS WITH FULL TO FILTERED SUN WILL HELP BOOST
HIGHS TO THE UPPER 40S TO LOWER 50S, WITHIN A DEGREE OR TWO OF
YESTERDAY. WHILE THIS WILL BE A COOL DAY TEMPERATURE WISE, THE
LIGHT WINDS AND SUN SHOULD PROVIDE A PLEASANT FEEL TO THE DAY.
TUESDAY NIGHT, LIGHT SOUTHEAST WINDS WILL BECOME SOUTH, AND BEGIN TO
WARM ADVECT. THIS PLUS SOME INCREASED CLOUDS WILL HELP KEEP LOWS UP
INTO THE LOWER TO MID 30S.
LONG TERM
(WEDNESDAY THROUGH MONDAY)
ISSUED AT 330 AM CDT TUE MAR 26 2019
WEDNESDAY
GUSTY SOUTHERLY WINDS WILL BOOST HIGHS INTO THE LOW TO MID 60S ON
AVERAGE. FORECAST SOUNDINGS SHOW DAYTIME MIXING INTO 40-50 KT
850MB SOUTHWEST FLOW WHERE TEMPS ARE NEAR 6-8 C.
WINDS: A LARGE AMOUNT OF DIRECTIONAL SHEAR SHOULD TEMPER THE MAX
GUSTS A BIT. HOWEVER, THE BOUNDARY LAYER FLOW WILL BECOME MORE
UNIDIRECTIONAL THROUGH THE AFTERNOON, COINCIDENT WITH THE PERIOD
OF STRONGEST SURFACE PRESSURE GRADIENT. FOR THESE REASONS, SEE
POTENTIAL FOR GUSTS AROUND 40 MPH WITH THE FAVORED AREA ACROSS THE
NORTHWEST CWA -- ROUGHLY ALONG AND NORTH OF A LINE FROM DUBUQUE
TO CEDAR RAPIDS TO SIGOURNEY. ELSEWHERE, 30-35 MPH CAN BE
EXPECTED. MAIN IMPACT FROM THE HIGHER GUSTS WOULD BE DIFFICULT
TRAVEL FOR HIGH PROFILE VEHICLES, ESPECIALLY ON WEST TO EAST
ROADS.
FIRE WEATHER: IF A GRASSLAND WILDFIRE WERE TO IGNITE WEDNESDAY
AFTERNOON, IT WOULD SPREAD QUICKLY THROUGH THE CURED/DORMANT
VEGETATION. ONE LIMITING FACTOR IS MIN RH VALUES BETWEEN 40-50%,
WHICH ARE TYPICALLY MUCH LOWER ON SIGNIFICANT GRASSLAND WILDFIRE
DAYS. NO FIRE WEATHER HEADLINES ARE ANTICIPATED AT THIS TIME
BECAUSE OF THE AVERAGE MIN RH VALUES.
THURSDAY
CONTINUED MILD WITH HIGHS IN THE 60S (MID 50S IN THE FAR NW).
HAVE SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT
INTO THURSDAY MORNING, BUT AREAL COVERAGE WITH THIS ACTIVITY LOOKS
TO BE LOW. STRONGER LARGE SCALE ASCENT AND DEEPER GULF OF MEXICO
TO MIDWEST WV TRANSPORT IS EXPECTED LATER THURSDAY INTO FRIDAY.
MODELS FOCUS THE FIRST WAVE OF RAIN IN THE SOUTHERN CWA THURSDAY
AFTERNOON THROUGH THURSDAY NIGHT.
FRIDAY
A SURFACE WARM FRONT IS FORECAST TO SET UP ALONG THE IOWA AND
MISSOURI BORDER, EXTENDING EAST INTO WEST-CENTRAL ILLINOIS.
CONVERGENCE AND FRONTOGENESIS WILL STRENGTHEN ALONG THE
AFOREMENTIONED FRONT AND SLOPE TO THE NORTH ALOFT OVER THE REST
OF IOWA AND NORTHERN ILLINOIS.
PRECIPITATION: STRONG FORCING AND SUFFICIENT MOISTURE WITH PWATS
NEAR 1 INCH MEANS MODERATE TO HEAVY PRECIPITATION IS EXPECTED
WITH THIS SYSTEM. WPC PLACES THE HEAVIEST QPF AXIS OF 1-2"+ ALONG
AND SOUTH OF HIGHWAY 30. IF THESE AMOUNTS ARE REALIZED, A RENEWED
ROUND OF TRIBUTARY RIVER FLOODING WOULD BECOME LIKELY. AND IT
WOULD BE BAD TIMING FOR ENHANCED TRIBUTARY OUTPUT TO ENTER INTO
THE MISSISSIPPI RIVER AS THE SNOWMELT CREST IS APPROACHING FROM
THE NORTH.
MODEL DISCREPANCIES: THE GFS AND ECMWF ARE IN GOOD AGREEMENT ON
WIDESPREAD PRECIPITATION OF 0.75 - 1.25 INCHES WITH A FEW
LOCALIZED BAND UP TO 1.50 INCHES, WHICH DOESN'T INCLUDE THE RAIN
THAT FALLS ON THURSDAY. THE CMC IS MUCH WETTER AND SLIGHTLY
FURTHER NW WITH THE HEAVIEST QPF AXIS, TAKING IT SQUARELY THROUGH
THE CWA.
SNOW: THERE MAY BE ENOUGH COLD AIR ON THE BACKSIDE OF THE 850MB
LOW TO CHANGE RAIN OVER TO SNOW FRIDAY NIGHT. IT'S TOO EARLY TO
KNOW IF THE SET UP WILL BE RIGHT FOR WET ACCUMULATIONS.
THE WEATHER QUIETS DOWN BEYOND SATURDAY WITH TEMPERATURE RUNNING
BELOW NORMAL. UTTECH
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 654 AM CDT TUE MAR 26 2019
VFR CONDITIONS WILL PREVAIL THROUGH THE NEXT 24 HOURS.
HYDROLOGY
ISSUED AT 907 PM CDT MON MAR 25 2019
I HAVE ISSUED AN UPGRADED WARNING FOR BELLEVUE LD12, WITH THE END
OF THE PERIOD NOW SOLIDLY ABOVE 18 FEET. THIS IS THE LONG TERM
RISE ARRIVING, AND NOT ASSOCIATED WITH NEW QPF. OTHERWISE, NO
SIGNIFICANT CHANGES NOTED. RCKI2, THE QUAD CITIES IS NEAR CREST
AROUND 18.5-18.6 FEET.
WITH JUST MINOR AMOUNTS OF RECENT RAINFALL AND MAINLY DRY WEATHER
EXPECTED THROUGH WEDNESDAY, ANOTHER RIVER FORECAST CYCLE WITHOUT
MAJOR CHANGES TODAY. THE CEDAR RIVER AT PALO DROPPED BELOW FLOOD
STAGE EARLY THIS MORNING, AND THE PECATONICA RIVER AT FREEPORT IS
CURRENTLY DROPPING BELOW THE FLOOD STAGE. OTHERWISE CONDITIONS
CONTINUE IMPROVING ON MOST AREA TRIBUTARY RIVERS WITH LEVELS
SLOWLY FALLING. THAT BEING SAID, THE ROCK RIVER AT MOLINE AND THE
WAPSI NEAR DE WITT CONTINUE IN THE MAJOR FLOOD STAGE, BUT BOTH ARE
FALLING AND ARE PROJECTED TO FALL UNDER THE MAJOR CATEGORY LATER
TONIGHT INTO EARLY TUESDAY MORNING.
MEANWHILE, RISES CONTINUE FROM ROUTED WATER FROM SNOW MELT UP NORTH
THROUGH THE MAINSTEM MISSISSIPPI RIVER NORTH OF THE QUAD CITIES,
WITH SEVERAL SITES IN THE MINOR TO MODERATE FLOOD CATEGORY. THIS
WHILE POINTS TO THE SOUTH OF THE QUAD CITIES ARE EXPERIENCING
MODERATE TO MAJOR FLOODING. BUT SEVERAL OF THESE SITES FROM THE QUAD
CITIES ON SOUTHWARD ARE EITHER NEARING A BROAD CREST, OR JUST
STARTING TO EXIT THE CREST STAGE AND BEGIN TEMPORARY SLOW FALLS
THROUGH THE END OF THE WEEK. RIVER LEVELS FROM QUAD CITIES ON
SOUTHWARD, WHILE BEGINNING SLOW FALLS, WILL STILL LARGELY REMAIN
ABOVE MAJOR FLOOD STAGE THROUGH THE NEXT 7 DAYS AND LIKELY BEYOND
AIDED BY ONGOING TRIBUTARY INPUT. UPSTREAM OF THE QUAD CITIES LEVELS
ON THE MISSISSIPPI RIVER WILL CONTINUE RISING THROUGHOUT THE NEXT 7
DAYS AND BEYOND DUE TO INCREASE IN FLOW FROM SNOWMELT ACROSS
MINNESOTA AND WISCONSIN. LOCK AND DAM 12 AT BELLEVUE WILL PROBABLY
NEED TO BE UPGRADED TO A WARNING FOR MODERATE FLOODING SOON WITH
RISES CONTINUING PAST DAY 7.
THERE WILL LIKELY BE ANOTHER CREST OR CRESTS ALONG THE MISSISSIPPI
AND ITS TRIBUTARY RIVERS WHEN THE REST OF THE SNOW ACROSS MINNESOTA
AND WISCONSIN MELTS. WHILE THE TIMING OF THESE POTENTIAL FLOOD
CRESTS IS UNCERTAIN, THE MOST LIKELY TIME FRAME STILL APPEARS TO BE
FROM AROUND APRIL 10TH THROUGH THE 25TH. IF TEMPERATURES ACROSS THE
MIDWEST ARE WARMER THAN THE CURRENT FORECASTS AND OUTLOOKS, THE NEXT
FLOOD CREST MAY MOVE FORWARD BY 6 TO 10 DAYS. ALSO, ANY HEAVY
PRECIPITATION IN THE REGION WOULD CAUSE A CHANGE IN TIMING OF THE
CRESTS AS WELL, OR PRODUCE ADDITIONAL SECONDARY CRESTS. IN
PARTICULAR, A POTENTIALLY HEAVY PRECIPITATION WINDOW TO BE AWARE OF
STILL LOOKS TO BE FROM THIS THURSDAY MARCH 28TH, THROUGH SATURDAY
MARCH 30TH. THERE STILL CONTINUES TO BE UNCERTAINTY ON THE EVENTUAL
PLACEMENT FROM NORTH TO SOUTH, AS WELL AS THE RAINFALL AMOUNTS ADDED
UP DURING THIS TIME. THERE ALSO CONTINUES TO BE THE CHANCE THAT THE
RAIN MAY CHANGE TO SNOW LATER FRIDAY NIGHT INTO SATURDAY IN
PORTIONS OF THE AREA.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...UTTECH
AVIATION...UTTECH
HYDROLOGY...ERVIN/12
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