Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 260006
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
706 PM CDT TUE AUG 25 2015

.SYNOPSIS...
ISSUED AT 322 PM CDT TUE AUG 25 2015

LOW PRESSURE THAT HAS BROUGHT CLOUDS TO MOST OF THE UPPER GRT
LAKES THE PAST COUPLE OF DAYS...ALONG WITH COOL AND DRY AIR TO OUR
AREA WAS GRADUALLY BEING ADVECTED TO THE EAST. HIGH PRESSURE WAS
BUILDING INTO THE AREA FROM THE WEST. THIS HIGH PRESSURE WILL
DOMINATE OUR WEATHER IN THE SHORT TERM.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 322 PM CDT TUE AUG 25 2015

MAIN FORECAST CONCERN FOR THE SHORT TERM ARE THE TEMPERATURES
OVERNIGHT AND HOW LOW THEY MIGHT GO. WITH THE HIGH PRESSURE MOVING
INTO THE AREA...CHANCES OF PATCHY FOG DEVELOPMENT SEEMS POSSIBLE
TONIGHT NEAR SUNRISE.

WITH THE LACK OF ANY APPRECIABLE H85 WAA...TEMPERATURES SHOULD BE
CLOSE TO WHAT THEY WERE TODAY AND LAST NIGHT. WITH THE HIGH
PRESSURE MOVING INTO THE AREA TONIGHT...THERE IS A POSSIBILITY THAT
TEMPERATURES COULD DROP SLIGHTLY COOLER THAN LAST NIGHT. AS A
RESULT...I TOOK AN ALLBLEND APPROACH AND LOWERED TEMPS A DEGREE OR
TWO. WITH THE HIGH PRESSURE AND CLEAR SKIES FORECAST FOR
TONIGHT...THERE IS ALSO A CHANCE FOR THE DEVELOPMENT OF PATCHY FOG
ACROSS THE AREA.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 322 PM CDT TUE AUG 25 2015

MAIN FOCUS IS ON THE SYSTEM LIKELY TO SPREAD RAIN AND POSSIBLE
THUNDERSTORMS THROUGH THE AREA FRIDAY AND FRIDAY NIGHT. THIS IS
FOLLOWED BY A WARMING TREND OVER THE WEEKEND INTO NEXT WEEK AS THE
UPPER PATTERN BECOMES LESS AMPLIFIED AND MORE PROGRESSIVE. CURRENT
MODEL BLENDS SUGGESTS THIS MAY RESULT IN HIGH TEMPERATURES RETUNING
TO THE 80S TO POSSIBLY LOWER 90S EARLY NEXT WEEK.

WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...EASTWARD RETREATING HIGH
PRESSURE OVER THE GREAT LAKES WILL EXTEND THE STRETCH OF DRY WEATHER
AND BELOW NORMAL TEMPERATURES. LIGHT SOUTHERLY WINDS...THE CONTINUED
DRY AIRMASS...AND WARMING ALOFT SHOULD LEAD TO WARMER HIGHS...FROM
THE MID 70S TO AROUND 80 AFTER ANOTHER NIGHT WITH LOWS IN THE 50S.
THURSDAY NIGHT...THE UPPER LEVEL SHORTWAVE MODELS EVOLVE FROM THE
MONSOONAL COMPLEX OVER AZ...IS SHOWN BY ALL MODELS DEEPENING OVER
THE CENTRAL PLAINS. CONSENSUS TIMING INDICATES FORCING MAY MOVE INTO
THE NW TO SUPPORT RAIN AND ISOLATED THUNDERSTORM CHANCES IN THE NW
AFTER MIDNIGHT. ELSEWHERE...INCREASING MID AND HIGH CLOUDS OUT
AHEAD...ALONG WITH SOUTHERLY WINDS AND LIGHT S-SE SURFACE WINDS
WILL LEAD TO WARMER MINS AND HAVE GONE CLOSE TO THE COOLER
GUIDANCE NUMBERS WITH UPPER 50S TO LOWER 60S.

12Z MODELS ARE IN SLIGHTLY BETTER AGREEMENT THAN PREVIOUS RUNS WITH
THE TIMING AND TRACK OF BOTH THE UPPER LEVEL SHORTWAVE AND SURFACE
LOW REFLECTED AT THE SURFACE...GENERALLY AGREEING MORE ON THE MORE
NORTHERLY POSITION. THE ECMWF REMAINS SOMEWHAT OF AN OUTLIER...
TRACKING THE SURFACE LOW ALONG THE IA/MO BORDER FRIDAY THROUGH
SATURDAY MORNING...AS OPPOSED TO THE GFS AND NAM THROUGH CENTRAL IA
WITH HEAVIEST QPF ACROSS NORTHERN IA INTO SOUTHERN WI. THE
CANADIAN SPLITS THE DIFFERENCE IN BETWEEN...WITH SLIGHTLY SLOWER
TIMING. WILL STAY WITH A BLEND...SKEWED TOWARD THE MORE NORTHERN
SOLUTIONS AND HAVE INCREASED POPS TO LIKELY IN THE NW CONSIDERING
THE GOOD CONTINUITY WITH THIS FEATURE OVER THE PAST COUPLE DAYS.
CHANCE POPS THEN FOLLOW FOR FRIDAY NIGHT INTO SATURDAY MORNING
WITH THE BEST UPPER FORCING GENERALLY FOCUSING ON THE FRIDAY
AFTERNOON AND FRIDAY EVENING PERIODS. THIS STILL LOOKS TO BE
GENERALLY A RAIN EVENT CONSIDERING THE LIMITED INSTABILITY AND
HAVE KEPT MENTION OF THUNDERSTORMS TO SLIGHT CHANCES THROUGHOUT.
WENT WITH MODEL BLEND QPF AMOUNTS FOR THE EVENT TOTALS IN A
QUARTER TO HALF INCH RANGE ACROSS THE NORTH FOR THE...WITH LIGHTER
AMOUNTS CENTRAL AND SOUTH...WHICH WOULD NEED TO BE TWEAKED IF THE
MORE SOUTHERLY SOLUTIONS APPEAR MORE LIKELY AS THE SYSTEM BECOMES
BETTER ESTABLISHED.

THE CLOUDS AND RAIN SHOULD HOLD HIGHS IN THE 70S AT BEST
FRIDAY...FOLLOWED BY A WARMING TREND SATURDAY THROUGH TUESDAY. MUCH
WARMER TEMPERATURES AT 850 MB BEGIN TO FEED INTO THE AREA MONDAY AND
ESPECIALLY TUESDAY AS THE UPPER FLOW BECOMES ZONAL TO SW WITH
ENHANCED WARMING POSSIBLE AHEAD OF THE NEXT FRONTAL SYSTEM. GOING
WITH THE CONSENSUS BLEND LEADS TO HIGHS IN THE MID TO UPPER 80S BY
TUESDAY...WHERE IT IS WORTH NOTING THE OUTLIER AND WARMEST GFS
ADVERTISES READINGS WELL INTO THE 90S. THIS WILL FAVOR MOISTURE AND
HUMIDITY LEVELS AND OVERNIGHT LOWS RETURNING TO MORE SEASONABLE
LEVELS/NORMALS...AFTER OUR RECENT RESPITE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 654 PM CDT TUE AUG 25 2015

WEAK HIGH PRESSURE WILL REMAIN OVER THE MIDWEST THE NEXT 24 HOURS.
SKIES WILL BE CLEAR OR MOSTLY CLEAR WITH SOME FAIR WEATHER CUMULUS
CLOUDS DURING THE DAY. WINDS WILL BE LIGHT OUT OF THE NORTHWEST AT
5 TO 10 KTS OR LESS.

&&

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

&&

$$

SYNOPSIS...GIBBS
SHORT TERM...GIBBS
LONG TERM...SHEETS
AVIATION...NICHOLS



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