963
FXUS63 KDVN 191750
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1250 PM CDT FRI OCT 19 2018
..AVIATION UPDATE
SYNOPSIS
ISSUED AT 242 AM CDT FRI OCT 19 2018
EARLY THIS MORNING THE LOCAL AREA WAS IN AN AREA OF WEAK RIDGING
UPSTREAM OF A SHORTWAVE TROUGH WITH ITS AXIS FROM NORTHERN
MINNESOTA INTO COLORADO. SCATTERED SHOWERS WERE OBSERVED AHEAD OF
THIS SYSTEM FROM EASTERN NEBRASKA INTO NORTHEAST MINNESOTA. A
SECONDARY AREA OF PRECIPITATION WAS OBSERVED FROM OKLAHOMA INTO
EASTERN KANSAS ASSOCIATED WITH A WING OF MOISTURE TRANSPORT AND
WARM AIR ADVECTION. CLOUD COVER, 10 MPH WINDS, AND WARM AIR
ADVECTION OVERNIGHT HAVE ALLOWED TEMPERATURES TO STAY MILD
OVERNIGHT, WITH READINGS IN THE 40S AND LOW 50S AT 08Z.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 242 AM CDT FRI OCT 19 2018
THE ELONGATED SHORTWAVE TROUGH OUT TO THE WEST WILL MOVE THROUGH
THE AREA TODAY. THIS WILL BRING SCATTERED TO WIDELY SCATTERED
SHOWERS TO MUCH OF THE FORECAST AREA THIS MORNING AND EARLY
AFTERNOON. AS THE SHORTWAVE MOVES THROUGH, THE MOST AMPLIFIED AREA
WILL MOVE ACROSS SOUTHERN MINNESOTA AND NORTHERN IOWA INTO
WISCONSIN AND NORTHERN ILLINOIS. THIS AREA IS ALSO ASSOCIATED WITH
THE LEFT ENTRANCE REGION OF THE UPPER LEVEL JET STREAK SO LIFT
SHOULD BE SUFFICIENT FOR WIDESPREAD SHOWERS. THE MOISTURE HOWEVER
IS LIMITED AND WILL BE VERY NARROW AHEAD OF THE SHORTWAVE. FOR
INSTANCE, MODELS ARE SHOWING THE DEEP LAYER MOISTURE WILL PUSH
ACROSS THE AREA IN A 3 HOUR TIME-SPAN. WHILE MOISTURE HAS BEEN
ADVECTING IN OVERNIGHT, THE DVN 19.00Z SOUNDING WAS QUITE DRY, PW
VALUE OF 0.31 INCHES, SO WHEN THE SHOWERS DO COME THROUGH THEY'LL
HAVE QUITE A BIT OF DRY AIR TO MOVE THROUGH. THIS SHOULD LIMIT ANY
PRECIPITATION TO LIGHT AMOUNTS, GENERALLY A TENTH OF AN INCH OR
LESS. FOCUSED THE HIGHEST RAIN CHANCES ACROSS THE NORTHERN PART OF
THE FORECAST AREA, WHERE THE BEST DYNAMICS WILL BE, BUT WILL
INCLUDE RAIN CHANCES THROUGHOUT THE FORECAST AREA. CLOUD COVER
WILL PERSIST FOR A FEW HOURS AFTER THE RAIN EXITS, WHICH COULD
IMPACT TODAYS TEMPERATURES. WARM AIR ADVECTION WILL BRING 850MB
TEMPERATURES RANGING FROM 9C TO 13C, BUT WITH CLOUDS PERSISTING
INTO THE AFTERNOON, DON'T HAVE MUCH CONFIDENCE IN HOW MUCH THE
SURFACE WILL WARM AND MIX TO TAKE ADVANTAGE OF THE WARMER
TEMPERATURES ALOFT. ULTIMATELY, KEPT HIGHS A BIT COOLER WHERE
CLOUDS ARE EXPECTED TO LINGER LONGER, BUT WILL NEED TO KEEP A
CLOSE EYE ON HOW THE SITUATION EVOLVES AND IF THERE WILL BE A NEED
TO UPDATE HIGHS AT SOME POINT. WINDS WILL ALSO BE A BIT STRONGER
TODAY, AS WINDS SHORTLY ABOVE THE SURFACE WILL BE BLOWING AT
20-35KTS. FORECAST SOUNDINGS WOULD SUGGEST MIXING TO ABOUT 875MB
SO SHOULD GET SOME PERIODS OF GUSTY CONDITIONS.
THE SHORTWAVE PUSHES EAST FAIRLY QUICKLY, WITH DRY CONDITIONS,
CLEARING SKIES, COOLER AIR, AND WINDS SHIFTING TO THE WEST-
NORTHWEST BY FRIDAY EVENING. DON'T EXPECT WINDS TO DROP OFF
THOUGH, KEEPING THE BOUNDARY LAYER MIXED, SO DESPITE THE COLD AIR
MOVING INTO THE REGION, (850MB TEMPS 0-2C) ONLY DROPPED LOWS
SATURDAY MORNING INTO THE UPPER 30S AND 40S.
LONG TERM
(SATURDAY THROUGH THURSDAY)
ISSUED AT 242 AM CDT FRI OCT 19 2018
VERY STRONG WINDS EXPECTED SATURDAY FOLLOWED BY MAINLY BELOW NORMAL
TEMPERATURES.
SATURDAY
ASSESSMENT...HIGH CONFIDENCE ON VERY STRONG WINDS. LOW TO MEDIUM
CONFIDENCE ON PRECIP CHANCES.
A POTENT UPPER LEVEL DISTURBANCE WILL MOVE THROUGH THE AREA ON
SATURDAY. WHILE THERE ARE SOME MINOR DIFFERENCES ON THE TRACK OF THE
SYSTEM, VERY STRONG WINDS WILL DEVELOP.
ONCE THE INVERSION BREAKS SATURDAY MORNING, WINDS WILL INCREASE
SIGNIFICANTLY WITH THE STRONGEST WINDS FROM LATE MORNING THROUGH MID-
AFTERNOON. SUSTAINED WINDS AROUND 25 MPH SHOULD EASILY BE ACHIEVED
WITH GUSTS OF 40-45 MPH.
DRY AIR MAY LIMIT THE OVERALL AREAL COVERAGE OF SHOWERS THAT OCCUR
WITH THE PASSAGE OF THE UPPER LEVEL SYSTEM. HOWEVER, SPRINKLES IF
NOT ISOLATED TO SCATTERED RAIN SHOWERS SHOULD BE SEEN ACROSS THE
NORTHEAST HALF OF THE AREA SATURDAY MORNING FOLLOWED BY DRY
CONDITIONS AND CLEARING SKIES IN THE AFTERNOON.
SATURDAY NIGHT
ASSESSMENT...HIGH CONFIDENCE
CLEAR AND COLD CONDITIONS WILL BE SEEN ACROSS THE AREA SATURDAY
NIGHT WITH LOW TEMPERATURES IN THE 20S.
SUNDAY AND SUNDAY NIGHT
ASSESSMENT...HIGH CONFIDENCE
QUIET AND DRY CONDITIONS WILL BE SEEN WITH TEMPERATURES AVERAGING
BELOW NORMAL.
MONDAY ON...
MONDAY THROUGH WEDNESDAY
ASSESSMENT...HIGH CONFIDENCE
DRY CONDITIONS WILL CONTINUE THROUGH THE FIRST HALF OF THE WEEK. A
DRY FRONTAL PASSAGE WILL OCCUR MONDAY AFTERNOON/EVENING THAT WILL BE
MARKED WITH ONLY AN INCREASE IN CLOUDS.
WEDNESDAY NIGHT AND THURSDAY
ASSESSMENT...LOW CONFIDENCE ON PRECIPITATION CHANCES
WEDNESDAY NIGHT RETURN FLOW DEVELOPS ACROSS THE AREA AS HIGH
PRESSURE MOVES INTO THE OHIO VALLEY. THE GLOBAL MODELS HAVE A STORM
SYSTEM FORECAST TO MOVE ACROSS THE DEEP SOUTH WHICH SHOULD INTERCEPT
MOST OF THE RETURN MOISTURE MOVING NORTH.
THE GLOBAL MODELS DISAGREE ON WHEN PRECIPITATION MOVES BACK INTO THE
AREA. THIS DISAGREEMENT APPEARS TO BE CENTERED AROUND THE STRENGTH
OF THE HIGH IN THE EASTERN GREAT LAKES/OHIO VALLEY AND THE AMOUNT OF
DRY AIR PRESENT.
THE GFS KEEPS THE ENTIRE AREA DRY WEDNESDAY NIGHT/THURSDAY WITH NOT
MUCH IN THE WAY OF PRECIPITATION IN WESTERN IOWA. THE CMC GLOBAL
KEEPS THE AREA DRY BUT DOES DEVELOP PRECIPITATION ACROSS WESTERN
IOWA. THE ECMWF ON THE OTHER HAND BRINGS LIGHT PRECIPITATION INTO
THE THE AREA WEDNESDAY NIGHT/THURSDAY WITH THE HELP OF AN UPPER
LEVEL DISTURBANCE.
AS A RESULT OF THESE DIFFERENCES, THE MODEL CONSENSUS HAS SLIGHT
CHANCE TO CHANCE POPS WEDNESDAY NIGHT AND THURSDAY MORNING.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1245 PM CDT FRI OCT 19 2018
MVFR CEILINGS ALONG A SURFACE TROUGH WILL IMPROVE TO VFR LATE
AFTERNOON OR EVENING. A REINFORCING COLD FRONT ON SATURDAY WILL
LEAD TO WINDY CONDITIONS WITH PEAK NW GUSTS NEAR 35 KTS. UTTECH
HYDROLOGY
ISSUED AT 1100 AM CDT FRI OCT 19 2018
MINOR TO MAJOR FLOODING CONTINUES ON SEVERAL RIVERS IN EASTERN
IOWA AND NORTHWEST ILLINOIS. LITTLE, IF ANY, RAINFALL IS EXPECTED
OVER THE NEXT 7 DAYS. ALL TRIBUTARY RIVERS WILL CONTINUE TO
SLOWLY FALL.
CORALVILLE LAKE RESERVOIR IS STILL NEAR CREST TODAY NEAR 710.9
FEET. IT WILL SLOWLY FALL OVER THE NEXT WEEK, REACHING 707 FEET
LATE NEXT WEEK.
ON THE MISSISSIPPI RIVER, ROUTED FLOW FROM UPSTREAM IS RESULTING
IN RISES; AND AT SOME LOCATIONS MINOR FLOODING; FROM DUBUQUE TO
LE CLAIRE. FROM THE QUAD CITIES TO MUSCATINE, SOME RISES WILL BE
SEEN THROUGH THE WEEKEND, BUT LEVELS WILL REMAIN WITHIN THE
MODERATE FLOOD CATEGORY. DOWNSTREAM OF MUSCATINE, THIS WILL
TEMPORARILY DELAY RECESSIONS. RIVER LEVELS WILL REMAIN HIGH INTO
NEXT WEEK.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SYNOPSIS...BROOKS
SHORT TERM...BROOKS
LONG TERM...08
AVIATION...UTTECH
HYDROLOGY...14
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