Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 192322
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
622 PM CDT FRI SEP 19 2014

.SYNOPSIS...
ISSUED AT 321 PM CDT FRI SEP 19 2014

12Z UA ANALYSIS HAS A WEAK LLJ RUNNING FROM THE SOUTHERN INTO THE
CENTRAL PLAINS. TROPICAL MOISTURE WAS BEING TRANSPORTED NORTHWARD
FROM NORTHERN MEXICO AND THE REMNANTS OF ODILE. SATELLITE TRENDS
THROUGH MID AFTERNOON SHOW VERY LITTLE IN THE WAY OF LOW AND MID
LEVEL CLOUDS WITH JUST SOME PASSING HIGH CLOUDS.

18Z SFC ANALYSIS HAS AN INFERRED WARM FRONT MOVING ACROSS MINNESOTA
WITH SEVERAL TROFS ACROSS THE DAKOTAS AND INTO NEBRASKA. THE NEXT
COLD FRONT WAS OVER THE WESTERN DAKOTAS AND INTO WYOMING. DEW POINTS
WERE IN THE 40S AND 50S ACROSS THE GREAT LAKES AND THE MISSISSIPPI
VALLEY. DEW POINTS IN THE 60S WERE ACROSS THE PLAINS AND LOWER
MISSISSIPPI VALLEY.

&&

.SHORT TERM...(TONIGHT AND SATURDAY)
ISSUED AT 321 PM CDT FRI SEP 19 2014

QUIET AND COOL CONDITIONS WILL BE SEEN THROUGH MIDNIGHT WITH
DECREASING WINDS. AFTER MIDNIGHT THINGS GET MORE INTERESTING.

THE MODELS DEVELOP CONVECTION THIS EVENING FROM EASTERN NEBRASKA
INTO SOUTHEAST MINNESOTA. THIS CONVECTION THEN MOVES GENERALLY EAST
AFTER MIDNIGHT. HOWEVER...THE OVERALL FORCING WEAKENS THROUGH
SUNRISE AND WINDS AT 5000 FEET BECOME WESTERLY. THUS THE BETTER
MOISTURE FOR CONVECTION REMAINS IN THE LOWER MISSOURI VALLEY.

SO...AFTER MIDNIGHT ISOLATED TO LOW END SCATTERED SHOWERS AND A FEW
THUNDERSTORMS SHOULD BEGIN MOVING INTO THE AREA NORTH OF HIGHWAY 30.

SATURDAY MORNING THE OVERALL FORCING CONTINUES TO WEAKEN. THE
CONVECTION SHOULD BECOME MORE ISOLATED WITH TIME AND MAY EVEN END
DURING THE MORNING. HEATING AHEAD OF THE COLD FRONT SHOULD
EVENTUALLY RESULT IN ISOLATED TO LOW END SCATTERED CONVECTION
DEVELOPING AROUND MID DAY OR EARLY AFTERNOON.

AREAL COVERAGE OF CONVECTION SHOULD INCREASE DURING THE AFTERNOON
WITH THE SOUTHEAST HALF OF THE AREA MOST FAVORED FOR THE HIGHER
POPS. HOWEVER...FORCING REMAINS WEAK AND THE JET SUPPORT ALOFT IS
NOT OVERLY FAVORABLE FOR THE DEVELOPMENT OF WIDESPREAD STRONG
CONVECTION.

SATURDAY WILL BE MORE HUMID AS OF LATE WITH HEAT INDEX READING
CLIMBING INTO MID AND POSSIBLY UPPER 80S ACROSS THE SOUTHEAST HALF
OF THE AREA.

.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 316 PM CDT FRI SEP 19 2014

OVERALL THE LONG TERM CONTINUES TO LOOK MAINLY DRY WITH NEAR NORMAL
TEMPS.

SATURDAY NIGHT...HAVE SLIGHT CHANCE POPS FAR S/E CWA FOR MAINLY
EARLY EVENING UNTIL FRONTAL PASSAGE AND ARRIVAL OF DRIER AIR.
ALSO... ADDED SMALL PCPN CHCS FAR NORTH IN THE EVENING
BEING BRUSHED BY PV ANOMALY ATTENDANT TO SHORTWAVE DIVING INTO THE
GREAT LAKES. HAVE OPTED TO KEEP OUT ANY MENTION AFTER 06Z FAR NORTH
WITH FCST SOUNDINGS SHOWING CONSIDERABLE DRYING OF THE ATMOS COLUMN.
OTHERWISE...SKIES OVERALL CLEARING WITH SOME CLOUDS LINGERING NORTH.
LOWS LOOK TO RANGE FROM NEAR 50 FAR NORTH TO NEAR 60 FAR SOUTH.

SUNDAY AND SUNDAY NIGHT...WILL HAVE TO WATCH PORTIONS OF NORTHWEST IL
FOR POTENTIAL OF STRAY SHOWER SUNDAY BEING IN CLOSER PROXIMITY TO
SECONDARY COLD FRONT ATTENDANT TO PASSING SHORTWAVE... BUT BANKING ON
INCOMING SUBSIDENCE AND CONTINUED DRYING OF COLUMN TO WIN OUT THUS
POPS WILL REMAIN BELOW MENTION. OTHERWISE...BREEZY CONDITIONS WITH
DEEP MIXING TO ABOVE 850 MB TAPPING WINDS AROUND 25 KTS. THIS AMOUNT
OF MIXING YIELDS HIGHS AROUND 70 OR LOWER 70S MAINLY. SUNDAY NIGHT
WITH CLEARING SKIES AND DIMINISHING WINDS WILL SET THE STAGE FOR COOL
NIGHT WITH LOWS MAINLY MID 40S TO AROUND 50... WITH POTENTIAL FOR FEW
DRAINAGE SITES TO DIP INTO LOWER 40S WITH ANY DURATION OF LIGHT WINDS.

MONDAY THROUGH TUESDAY...GREAT WEATHER WITH HIGH PRESSURE IN CONTROL
WITH MAINLY CLEAR SKIES AND LIGHT WINDS AND HIGHS MAINLY IN THE
LOWER 70S... AND LOWS IN THE 40S TO AROUND 50.

WEDNESDAY THROUGH FRIDAY...FAVORED MORE CONSISTENT ECMWF WITH HANDLING
OF NEXT UPPER TROUGH IN BLOCKING PATTERN. HIGH PRESSURE WILL GRADUALLY
SHIFT EAST DURING THE PERIOD. WINDS INITIALLY WILL BE FROM THE
SOUTHEAST AND WILL PULL IN DRIER AIR FROM DEPARTING HIGH... WHICH
WITH RIDGING ALOFT SLOWING EASTWARD PROGRESSION OF UPPER TROUGH
WILL HOLD ANY RAIN AT BAY WELL TO OUR WEST AT THE START OF THE PERIOD.
EVENTUALLY...SOME RAIN SHOWERS MAY DEVELOP INTO OUR WESTERN CWA BY
THURSDAY INTO THURSDAY NIGHT AS WEAKENING TROUGH LIFTING NORTHEAST GRAZES
CWA. ANY RAIN WILL BE SPARSE AND LIGHT IN AMOUNTS WITH SURFACE RIDGING
INTO THE GULF OF MEXICO PREVENTING ANY ENTRAINMENT OF DEEPER GULF MOISTURE.
HIGHS LOOK TO GRADUALLY MODERATE FROM MAINLY LOWER 70S TO UPPER 70S TO
NEAR 80 BY END OF WEEK...WITH LOWS ALSO MODERATING SOME BUT STAYING MAINLY
IN THE 50S.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 617 PM CDT FRI SEP 19 2014

VFR WEATHER AND SOUTHERLY WINDS WILL CONTINUE OVERNIGHT...AS A
COLD FRONT APPROACHES THE REGION FROM MINNESOTA. THIS MAY BRING A
THREAT FOR SCATTERED SHOWERS AND THUNDERSTORMS TO EASTERN IOWA
AFTER 09Z/20. THIS ACTIVITY IS HANDLED WITH A VICINITY WORDING IN
THE TAFS DUE TO THE LOW COVERAGE OF ACTIVITY. THE COLD FRONT
SHOULD BE EAST OF IOWA AND NORTHWEST ILLINOIS BY SATURDAY
AFTERNOON...WITH WINDS BECOMING WEST AT 10 TO 20 KTS AT THAT TIME.
VFR CONDITIONS WILL PERSIST THROUGH THE ENTIRE PERIOD...BUT COULD
DROP TO MVFR IF AN ISOLATED SHOWER OR STORM WERE TO IMPACT A
TERMINAL DIRECTLY SATURDAY MORNING.
ERVIN

&&

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

$$

SYNOPSIS...08
SHORT TERM...05
LONG TERM...05
AVIATION...ERVIN





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