319
FXUS63 KDVN 161717
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1217 PM CDT WED OCT 16 2013
.UPDATE...
ISSUED AT 1210 PM CDT WED OCT 16 2013
THE EARLIER CONCERN IS BEING REALIZED...TEMPERATURES ARE BARELY
MOVING IF AT ALL. THUS MAX TEMPERATURES ARE BEING LOWERED AGAIN.
SATELLITE TRENDS SHOW DIURNAL COLD WX CLOUDS DEVELOPING ON THE
BACK SIDE OF THE LOW CLOUDS. THESE CLOUDS WILL PERSIST THROUGH
SUNSET AND THEN DISSIPATE. HOWEVER...THE EFFECT WILL BE TO DELAY
ANY CLEARING FURTHER. TRENDS FROM THE RAP ARE NOW POINTING TO
KEEPING CLOUDS ACROSS MOST OF THE AREA THROUGH SUNRISE WITH
CLEARING ON THURSDAY AS THE UPPER LEVEL DISTURBANCE MOVES
NORTHEAST. THUS MIN TEMPERATURES FOR TONIGHT HAVE BEEN RAISED IN
ANTICIPATION OF CLOUDS REMAINING ACROSS THE AREA. ..08..
UPDATE ISSUED AT 1028 AM CDT WED OCT 16 2013
SPOTTY DRIZZLE APPEARS TO BE ASSOCIATED WITH LIFT FROM THE 700 AND
500MB TROFS AND LOW CONDENSATION PRESSURE DEFICITS AT 700MB. RAP
TRENDS HAVE THE OVERALL LIFT DISSIPATING DURING THE AFTERNOON
SUGGESTING THE POTENTIAL FOR DRIZZLE INTO THE EARLY AFTERNOON. IF
THE TRENDS WITH THE RAP ARE CORRECT...AREAS GENERALLY ALONG/NORTH
OF HWY 30 WOULD BE FAVORED FOR DRIZZLE.
TEMPERATURES SO FAR HAVE RESPONDED A FEW DEGREES SINCE THE
OVERNIGHT MINS. TRENDS WILL BE MONITORED BUT THE POTENTIAL EXISTS
FOR ANOTHER LOWERING OF MAX TEMPERATURES BY A FEW MORE DEGREES.
UPDATE ISSUED AT 842 AM CDT WED OCT 16 2013
BASED ON CURRENT SATELLITE TRENDS...CLEARING LOOKS DOUBTFUL PRIOR
TO SUNSET. RECENT RAP TRENDS ALSO SUGGEST CLOUDS REMAINING ACROSS
THE AREA AS WELL DURING THE DAYLIGHT HOURS. CLOUD COVER COMBINED
WITH THE WEAKENING OCTOBER SUN INDICATE A VERY SMALL DIURNAL RISE
IN TEMPERATURES DURING THE DAY. ..08..
&&
.SYNOPSIS...
ISSUED AT 300 AM CDT WED OCT 16 2013
A POSITIVELY TILTED UPPER TROF EXTENDED FROM THE WESTERN GREAT
LAKES INTO SOUTHERN CA AND AZ TUESDAY EVENING. A SURFACE LOW WAS
LOCATED OVER LAKE SUPERIOR WITH CYCLONIC FLOW AROUND THE LOW
EXTENDING WEST INTO SOUTHWESTERN MN AND WESTERN IA. WIDESPREAD LOW
CLOUDS WERE ASSOCIATED WITH THE CYCLONIC FLOW. SOME PATCHY DRIZZLE
OR LIGHT RAIN WAS OCCURRING FROM CENTRAL MN INTO NORTHERN IA.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 300 AM CDT WED OCT 16 2013
CLOUDS TRENDS WILL BE THE MAIN CONCERN TODAY AND TONIGHT AS THE
GREAT LAKES SURFACE LOW MOVES OFF TO THE NORTHEAST AND THE
TRAILING CYCLONIC FLOW WEAKENS. THE LOW CLOUDS HAVE OVERSPREAD THE
ENTIRE AREA EARLY THIS MORNING AND EXTEND INTO EASTERN NE AND
SOUTH DAKOTA SO IT/S DOUBTFUL THAT ANY CLEARING WILL OCCUR TODAY
WITH THE CYCLONIC FLOW REMAINING OVER THE AREA. PATCHY DRIZZLE OR
LIGHT RAIN SHOULD BE CONFINED TO THE NORTHERN HALF OF THE FORECAST
AREA TODAY. THERE IS SOME DISAGREEMENT BETWEEN THE MODELS ON
CLEARING TONIGHT. THE GFS SUGGESTS THE WEST WILL SEE SOME CLEARING
LATE WHILE THE NAM HOLDS HIGH H8 RH OVER THE ENTIRE AREA THROUGH
12Z THURSDAY ALONG WITH SOME WEAK LOW LEVEL
CONVERGENCE...SUPPORTING LITTLE IF ANY CLEARING. IF THE LOW CLOUDS
WOULD CLEAR OVER PARTS OF THE AREA TONIGHT...ANY CLEARING SHOULD
BE BRIEF WITH MID/HIGH CLOUDS SPREADING OVER THE AREA AHEAD OF A
S/W LIFTING OUT OF THE SOUTHWESTERN U.S. THE S/W WILL ALSO BRING A
LOW CHANCE OF SOME LIGHT RAIN TO THE SOUTHEASTERN THIRD AFTER
MIDNIGHT.
THE EXTENSIVE CLOUD COVER WILL KEEP TEMPERATURES FROM CHANGING
MUCH TODAY AND TONIGHT. 50S ARE EXPECTED TODAY WITH OVERNIGHT LOWS
IN THE UPPER 30S AND LOWER 40S.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 300 AM CDT WED OCT 16 2013
PATTERN CHANGE TO A PREVAILING NW FLOW TO BRING ABOUT A CHANGE TO
BELOW TEMPERATURES BY THE WEEKEND...WHICH WILL REMAIN PLACE
THROUGH MUCH OF NEXT WEEK. IN THE TRANSITION...WEAK SYSTEMS WILL
BRING PERIODIC CHANCES FOR LIGHT PRECIPITATION LATE THIS WEEK INTO
THE WEEKEND.
THURSDAY THROUGH FRIDAY NIGHT...VERY LIGHT RAIN OR DRIZZLE ASSOCIATED
WITH ISENTROPIC LIFT UNDER THE SHORTWAVE EXITING TO THE EAST WILL BE
HANDLED WITH VERY LOW POPS THU MORNING. BY AFTERNOON...A
TRANSITORY MID LEVEL SHORTWAVE RIDGE THAT FOLLOWS SHOULD BRING
CLEARING SKIES ALLOWING TEMPERATURES TO RECOVER INTO THE LOWER TO
MID 60S. ANOTHER SHORTWAVE AND THE BROAD CYCLONIC FLOW ALOFT SHOULD
BRING INCREASING CLOUDS OVERNIGHT...BUT WITH THE BEST FORCING WELL
TO THE NORTH...WILL NOT ANTICIPATE ANY PRECIPITATION. CLOUD COVER
SHOULD CONFINE MINS TO THE UPPER 30S TO LOWER 40S. THE NEXT SYSTEM
BRUSHES PAST TO THE SOUTH LATE FRIDAY AND WILL HAVE SLIGHT CHANCE
POPS FOR LIGHT RAIN ACROSS THE SOUTH FOR FRIDAY NIGHT. COLD
ADVECTION GRADUALLY INCREASES THROUGH THIS PERIOD...AND BY FRIDAY
NIGHT...850 MB TEMPERATURES NEAR TO BELOW ZERO CELSIUS ARE PROGGED
OVER THE AREA. WILL THUS NEED DEEP MIXING TO REACH HIGHS IN THE 50S
FRIDAY...THEN CLOUD COVER TO MAINTAIN LOWS IN THE MID TO UPPER 30S
FRIDAY NIGHT.
OVER THE WEEKEND...THE NEXT SHORTWAVE IS GENERALLY DEPICTED PASSING
TO THE NORTH AROUND SATURDAY NIGHT...AND WILL MAINTAIN ONLY SLIGHT
CHANCES FOR RAIN IN THE FAR NORTH. OTHERWISE...IMPROVING MODEL
CONSISTENCY...BOTH FROM RUN TO RUN AND BETWEEN MODELS...SHOW 850 MB
TEMPERATURES COOLING TO ZERO TO 4 BELOW BY SUNDAY SUPPORT WELL BELOW
NORMAL SURFACE TEMPERATURES. ADVERTISED HIGHS IN THE 50S MAY BE TOO
OPTIMISTIC...ESPECIALLY SUNDAY DEPENDING ON CLOUD TRENDS.
LIKEWISE...CURRENT OVERNIGHT LOWS COULD POTENTIALLY BE COLD ENOUGH
FOR A WIDESPREAD KILLING FREEZE...ESPECIALLY SUNDAY MORNING.
HOWEVER...FOR NOW...WITH UNCERTAINTIES IN CLOUD COVER AND THE TIMING
OF PASSING SURFACE RIDGE AXIS...LOWS WILL BE MAINTAINED IN THE 30S.
NEXT WEEK...A CYCLONIC NW FLOW WITH PERIODIC SHORTWAVES AND
REINFORCING SURFACE COLD FRONTS SETS UP OVER THE AREA THROUGH MOST
OF THE WEEK. THERE IS HIGH CONFIDENCE THAT MUCH OF THE WEEK WILL
FEATURE BELOW TO WELL BELOW NORMAL TEMPERATURES. HOWEVER...
CHALLENGES WITH THE CRITICAL TIMING AND STRENGTH OF PASSING
SHORTWAVES MAKES THIS A LOW PREDICTABILITY PATTERN THIS FAR OUT. FOR
NOW...THERE IS ENOUGH CONSENSUS IN THE MODEL BLENDS TO PLACE LOW
CHANCE POPS OVER MAINLY THE NORTH FOR SUNDAY NIGHT INTO MONDAY...AND
THEN MORE WIDESPREAD HIGHER CHANCES FOR TUE INTO TUE NIGHT. THE
LATEST GFS AND ECMWF INDICATE A STRONG SURGE OF COLD AIR BEHIND
TUESDAY NIGHT/S COLD FRONT...THAT COULD LIMIT MIDWEEK HIGHS TO THE
UPPER 30S OVER AT LEAST THE NORTH AND RESULT IN WIDESPREAD 20S FOR
LOWS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1210 PM CDT WED OCT 16 2013
MVFR CONDITIONS WITH A FEW POCKETS OF IFR CIGS WILL PERSIST
THROUGH 00Z/17 AS MOISTURE REMAINS TRAPPED BELOW THE INVERSION.
AFT 00Z/17 MVFR CONDITIONS WILL CONTINUE WITH A SLOW IMPROVEMENT
TO VFR CIGS. AFT 12Z/17 CLEARING WILL COMMENCE FROM SOUTHWEST TO
NORTHEAST. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...DLF
SHORT TERM...DLF
LONG TERM...SHEETS
AVIATION...08