Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 271737
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1237 PM CDT SAT JUN 27 2015

.UPDATE...
ISSUED AT 1236 PM CDT SAT JUN 27 2015

VISIBLE SATELLITE IMAGES AND SURFACE WIND FIELDS SHOW A WEAK
CONVERGENCE AXIS ROUGHLY ALONG THE MS RIVER FROM SE OF DBQ THROUGH
THE QUAD CITIES TO MACOMB IL. RECENT RADAR IMAGES SHOW A FEW VERY
WEAK RETURNS NEAR THE MACOMB AREA. THIS AXIS IS WHERE THE GREAT
LAKES AIRMASS WITH ITS SLIGHTLY LOWER DEWPOINTS CONVERGED WITH
THE WEAK MORE NORTHERLY FLOW OUT OF THE SURFACE RIDGE AXIS LOCATED
FROM EASTERN NEB TO NORTHERN WI.

IT WILL BE THIS ALONG AXIS WHERE ISOLATED SHOWERS MAY FIRST DEVELOP
EARLY THIS AFTERNOON. THE COVERAGE AND INTENSITY OF SHOWERS WILL
BE LIMITED BY A CONVERGENT...SUBSIDENT FLOW ALOFT AS A SHORTWAVE
RIDGE OVER THE UPPER MS VALLEY MIGRATES OVER THE REGION THIS
AFTERNOON. WILL THUS KEEP ONLY SLIGHT CHANCE POPS FOR SHOWERS AND
BRIEF THUNDERSTORMS GOING FOR THIS AFTERNOON WITH TEMPERATURES ON
TRACK TO TOP OUT IN THE UPPER 70S TO NEAR 80.

&&

.SYNOPSIS...
ISSUED AT 400 AM CDT SAT JUN 27 2015

UPPER LEVEL LOW WAS SITUATED IN LOWER MI WITH THE BULK OF THE RAIN
WELL TO OUR EAST. HOWEVER...THERE IS JUST ENOUGH SURFACE CONVERGENCE
TO DEVELOP A FEW 50DBZ SHOWERS IN NORTHERN IL AS CLOSE AS ROCHELLE
AND OREGON IN OGLE COUNTY. THESE SHOWERS WERE MOVING SOUTHWEST AND
SHOULD TURN MORE SOUTHERLY AROUND THE UPPER LOW. THE FARTHER WEST
THEY GET THE CONVERGENCE WEAKENS SO NOT EXPECTING THE SHOWERS TO
MAKE IT INTO THE DVN CWA. HOWEVER...WILL MONITOR RADAR TRENDS.

MEANWHILE BACK AT THE RANCH...SKIES IN THE CWA WERE CLEAR TO
PARTLY CLOUDY WITH 3 AM TEMPERATURES IN THE UPPER 50S TO LOWER 60S
SO A RATHER COMFORTABLE EARLY MORNING IN PROGRESS.

ELSEWHERE...WATER VAPOR LOOPS SHOW A WEAK VORT MAX DIVING INTO
NORTHERN IA AND ANOTHER STRONGER WAVE IN MANITOBA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT JUN 27 2015

FORECAST FOCUS ON ISOLATED SHOWERS OR STORMS THIS AFTERNOON THEN
THUNDERSTORMS LIKELY IN OUR NW CWA LATE TONIGHT.

TODAY...APPARENTLY MOTHER NATURE WILL NOT ALLOW FOR A DRY DAY AS
OPERATIONAL MODELS SUGGEST ISOLATED SHOWERS AND THUNDERSTORMS
DEVELOPING THIS AFTERNOON...MAINLY NEAR AND WEST OF THE MS RIVER.
THE HRRR DEVELOPS THIS BY EARLY AFTERNOON BUT DIMINISHES THE
ACTIVITY TOWARDS EVENING. I CERTAINLY CAN/T IGNORE THE FACT THAT
THERE WILL BE WEAK CONVERGENCE AT THE SURFACE/LOW LEVELS...THE
CONVECTIVE TEMPERATURE IN THE MID 70S WILL BE REACHED BY EARLY
AFTERNOON AND LAPSE RATES STEEPEN ALONG WITH ENOUGH MOISTURE.
THERE WILL ALSO BE A WEAK VORT MAX TO AID LIFT. THEREFORE...HAVE
ADDED THE MENTION OF NEAR 20 PERCENT POPS FOR THIS AFTERNOON IN
ROUGHLY OUR WESTERN HALF. ANY STORM THAT DEVELOPS COULD CAUSE
BRIEF HEAVY DOWNPOURS BUT EXPECTING ISOLATED COVERAGE WHICH MEANS
MOST AREAS SHOULD REMAIN DRY ALONG WITH MOSTLY SUNNY TO PARTLY
CLOUDY SKIES. THIS WILL BE ANOTHER DAY OF BELOW NORMAL
TEMPERATURES...WITH HIGHS IN THE UPPER 70S. THIS IS BASED ON USING
THE SURFACE PARCEL TRAJECTORY METHOD WITH OUR AIRMASS COMING FROM
NORTHERN WI WHERE THEIR OBSERVED HIGHS YESTERDAY WERE IN THE UPPER
70S.

TONIGHT...SHOULD BE A DRY EVENING BUT THEN ECMWF/GFS/NAM/CANADIAN
ALL SIMILAR IN ROLLING SHOWERS AND THUNDERSTORMS INTO OUR NW CWA
BY LATE TONIGHT. THIS WILL BE AHEAD OF A SIGNIFICANT SHORT WAVE
TROUGH IN THE NORTHWEST FLOW PROVIDING DECENT FORCING. DEEP LAYER
SHEAR WILL BE GRADUALLY INCREASING ALONG WITH PRECIPITABLE WATER
INCREASING TO OVER 1 INCH WHILE SHOWALTERS DROP INTO THE NEGATIVE
NUMBERS. THEREFORE...I HAVE RAISED POPS TO LIKELY IN THE FAR NW BY
SUNRISE. MINIMUM TEMPERATURES WILL BE COMFORTABLE AGAIN BEFORE THE
CLOUDS ARRIVE. LOWS WILL RANGE FROM THE MID 50S FAR EAST TO THE
LOWER 60S FAR WEST.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT JUN 27 2015

LITTLE CHANGE NOTED IN OVERALL PATTERN WITH ACTIVE NORTHWEST FLOW
TO PERSIST THROUGH THE PERIOD AND TEMPS NEAR TO BELOW NORMAL.

SUNDAY AND SUNDAY NIGHT...GOOD FORCING WITH SHORTWAVE AND FAVORABLE
LEFT EXIT REGION LIFT QUADRANT OF 80 PLUS KT 300 MB JET DIVING
FROM NORTHERN PLAINS THROUGH MID MISSISSIPPI VALLEY... AND WEAK
SURFACE CYCLONE WITH TRIPLE POINT ALL SUPPORTIVE OF WIDESPREAD
SHOWERS AND A FEW STORMS SUNDAY INTO SUNDAY EVE. THE PRECIPITATION
SHOULD CONTINUE SLIDING S/E SUNDAY AM WITH REDEVELOPMENT DURING
THE AFTN. HEAVIEST RAINS 0.5 TO 1 PLUS INCHES SUGGESTED TO FALL
ACROSS PORTIONS OF THE WESTERN AND SOUTHERN CWA VICINITY OF TRIPLE
POINT AHEAD OF SURFACE LOW AS LAYER PRECIPITABLE WATER VALUES
SURGE TO NEARLY 1.5 INCHES. THIS WILL NEED TO BE WATCHED FOR FLASH
FLOODING ISSUES ESPECIALLY FOR SOUTHERN CWA WHICH HAS BEEN HIT
HARD WITH SIGNIFICANT RAINS OF LATE AND GROUND IS SATURATED.
CONDITIONAL RISK FOR STRONG TO ISOLATED SEVERE STORMS EXISTS AND
THIS IS DEPENDENT ON AMOUNT OF SOLAR INSOLATION AND SUBSEQUENT
DESTABILIZATION. AT THIS TIME...EXCEPT FOR A WHILE SUNDAY AM
MAINLY SOUTH/EAST CWA... I DO NOT FORESEE A LOT OF SOLAR
INSOLATION AND AS SUCH HAVE LOWERED MAX TEMPS A BIT (WIDESPREAD
70S) LEADING TO LOW THREAT FOR A STRONG TO ISOLATED SEVERE STORM.
HOWEVER... IF MORE SUNSHINE AND SUBSEQUENT INSTABILITY OCCURS THAN
CURRENTLY ANTICIPATING THEN THREAT FOR A FEW SEVERE STORMS WILL
INCREASE GIVEN PRESENCE OF STRENGTHENING 0-6 KM BULK SHEAR 30-40
KTS DURING THE AFTN. PRECIPITATION SHOULD TAPER OFF FROM NORTHWEST
TO SOUTHEAST SUNDAY EVENING WITH SOME CHANCE OF SHOWERS LINGERING
OVERNIGHT IN WRAP-AROUND OVER NORTH AND EAST PORTIONS OF THE CWA.

MONDAY THROUGH FRIDAY... A SERIES OF DISTURBANCES IN NORTHWEST FLOW
WILL BRING PERIODIC RAIN CHANCES NEXT WEEK. TRYING TO TIME THESE
WAVES REMAINS VERY DIFFICULT THIS FAR OUT AND UNFORTUNATELY
DICTATES THE DAILY BARRAGE OF RAIN CHANCES IN THE FORECAST EVEN
THOUGH WE SHOULD SEE MANY DRY HOURS. TEMPS NEAR TO BELOW NORMAL
WITH HIGHS MAINLY IN THE 70S TO NEAR 80 AND LOWS IN THE 50S/60S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1236 PM CDT SAT JUN 27 2015

ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON ARE EXPECTED TO
BE TOO FEW AND FAR APART TO AFFECT THE TERMINALS AND HAVE BEEN
LEFT OUT OF THE FORECASTS FOR NOW. HIGH PRESSURE...BOTH AT THE
SURFACE AND ALOFT WILL KEEP CONDITIONS VFR WITH LIGHT NORTH
WINDS. TONIGHT...AN INCOMING UPPER LEVEL DISTURBANCE MAY SPREAD
THUNDERSTORMS INTO EASTERN IA...MAINLY NW OF THE CID AND DBQ
TERMINALS TOWARD SUNRISE. A BETTER CHANCE FOR MORE WIDESPREAD
SHOWERS AND THUNDERSTORMS WILL ARRIVE LATER SUNDAY MORNING...AND
PROB30 GROUPS HAVE BEEN INTRODUCED FOR THUNDERSTORMS WITH MVFR
CONDITIONS AT ALL SITES.

&&

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

$$

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


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