674
FXUS63 KDVN 072103
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 PM CST SAT NOV 7 2009
SYNOPSIS
CLEAR SKIES AND UNSEASONABLY WARM TEMPERATURES WERE THE RULE THIS
AFTERNOON DESPITE A WEAK COLD FRONT ADVANCING SOUTHEAST THROUGH THE
AREA. AT 2 PM...THE FRONT...WHICH WAS PRIMARILY A PRESSURE TROUGH
AND WIND SHIFT...EXTENDED FROM NE TO SW FROM FREEPORT TO
KIRKSVILLE. AHEAD OF THE FRONT...TEMPERATURES WERE IN THE LOWER TO
MID 70S...WITH UPPER 60S TO AROUND 70 TRAILING THE FROPA IN EASTERN
IA. LACK OF MOISTURE IN A MOSTLY ZONAL FLOW ALOFT WAS PROVIDING
NEARLY FULL SUNSHINE OVER A LARGE PART OF THE CENTRAL AND EASTERN
CONUS. 12Z UPPER AIR ANALYSIS AND LATEST WV IMAGERY INDICATED THE
NEXT MID LEVEL SHORTWAVE MOVING INTO THE NW CONUS TOWARD THE
NORTHERN ROCKIES. THIS IS PROGGED TO INDUCE A RETURN FLOW...SENDING
THE WEAK FRONT BACK NORTHWARD THROUGH THE REGION SUNDAY.
SHORT TERM...TONIGHT AND SUNDAY
TEMPERATURES ARE THE PRIMARY FOCUS. THE MAIN PUSH OF COLD ADVECTION
AT THE 925 AND 850MB LEVELS WAS SHOWN IN SHORT TERM MODELS LAGGING
WELL BEHIND THE SURFACE FRONT THIS AFTERNOON...AS CLOSE AS MN INTO
FAR NE IA BETWEEN 18Z AND 00Z. THIS APPEARS TO HAVE MINIMAL IMPACT AS
IT CONTINUES TO WEAKEN AND STALL OVERHEAD TONIGHT BECOMING ORIENTED
MORE PARALLEL TO THE UPPER LEVEL FLOW. AT THE SURFACE...THE MAJORITY
OF SHORT TERM MODELS HAVE THE FRONT STALLING ACROSS FAR SE IA INTO W
CENTRAL IL OVERNIGHT WITH WEAK SURFACE HIGH PRESSURE...CURRENTLY IN
SE SD...SLIDING NEB ACROSS NRN IA TO SRN WI BY MIDNIGHT.
AS LOW LEVEL RETURN FROM THE NEXT SYSTEM DEVELOPS LATE TONIGHT...
RESULTING FRONTOGENESIS AND LOW LEVEL MOISTURE CONVERGENCE MAY
PRODUCE LOW CLOUDS INTO THE SOUTH TOWARD SUNRISE. HOWEVER...
CONFIDENCE NOT HIGH THAT THIS WILL RESULT IN SIGNIFICANT LOW LEVEL
CLOUD COVERAGE AND WILL STAY WITH PARTLY CLOUDY SKIES. LIGHT WINDS
AND MOSTLY CLEAR SKIES SHOULD ALLOW TEMPERATURES TO RADIATE OUT MORE
THAN LAST NIGHT AND HAVE GONE ROUGHLY 2 TO 5 DEGREES COOLER...IN THE
MID 40S NORTH TO LOWER 50S SOUTH.
SUNDAY WILL SEE THE SURFACE FRONT PUSHING BACK NORTH AS A WARM FRONT
SHOWN REACHING THE HIGHWAY 20 CORRIDOR BY MIDDAY. RESULTING SW
RETURN FLOW AT 925 AND H8 PUSHING TEMPERATURES BACK TO ROUGHLY 2
DEGREES SHY OF TODAY/S VALUES...SHOULD RESULT IN ANOTHER VERY MILD
DAY FOR EARLY NOV AS LACK OF MID AND HIGH LEVEL MOISTURE ALLOWS MORE
SUNSHINE AND SIMILAR MIXING DEPTHS. MIXING TO AT LEAST 925 MB...
HIGHS SHOULD REACH THE UPPER 60S NORTH TO LOWER 70S SOUTH.
..SHEETS..
LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY
..LIGHT TO MODERATE RAIN EVENT MONDAY
THEN DRY WITH MAINLY ABOVE
NORMAL TEMPERATURES INTO FRIDAY WITH MORE RAIN NEXT WEEKEND...
SOLUTION INITIALIZATION ABOVE AVERAGE WITH VERIFICATION SUPPORTS HI-
RES ECMWF WITH SOME FORCING INPUTS FROM GFS. PRIMARY ISSUE IS THE
PHASING OF TROPICAL STORM "IDA" WITH APPROACHING NEXT WAVE EARLY NEXT
WEEK.
SUNDAY NIGHT THROUGH MONDAY NIGHT...TREND IS FOR AT LEAST A MODERATE
RAINFALL EVENT SE 2/3 CWFA AS DEWPOINTS RISE WELL INTO LOWER 50S
AHEAD OF COOL FRONT. THIS COMBINED WITH DECENT BOUNDARY AND SHORT
WAVE LIFTING NE FROM SOUTH PLAINS SUGGEST ALL SOLUTIONS STILL TOO DRY
OVERALL WITH PRECIPITATION. LOCAL TOOLS SUGGEST WIDESPREAD 1 TO 3+
TENTHS AMOUNTS WITH LOCALLY HIGHER AMOUNTS POSSIBLE. LOCAL
INSTABILITY TOOL SUGGEST ISOLATED RUMBLES OF THUNDER MAY OCCUR
MONDAY...BUT NEED STRONG MID LEVEL FORCING. THIS DOES NOT APPEAR TO
BE IN THE CARDS DUE TO LIMITED PHASING WITH "IDA' ATTM. PASS FOR
LATER SHIFTS TO REASSESS DUE TO THE PHASING QUESTION...PLUS MODEL
SMOOTHING THIS FAR OUT. MINS SUNDAY NIGHT WITH CLOUDS AND MOISTURE
POOLING MAY STILL BE A FEW DEGREES TOO COOL. DECENT TEMP GRADIENT FOR
HIGHS MONDAY WITH FRONT AND EVAPORATIVE COOLING WITH PRECIPITATION
SUGGESTED AND NW SECTIONS POSSIBLY UP TO 5 DEGREES TOO MILD FOR LATER
SHIFTS TO RECONSIDER. MONDAY NIGHT...LINGERING RAIN TO END WITH
LIMITED COOLING. KEY ISSUE OF PHASING OF ENERGY FROM TS "IDA" KEY TO
CLOUDS AND IMPACTS ON TEMPS/POPS MONDAY NIGHT...THIS SHOULD BECOME
MORE EVIDENT NEXT 12-24 HOURS.
TUESDAY THROUGH THURSDAY...DRY THOUGH PERIOD AND NEAR NORMAL
TEMPERATURES TUESDAY RISING TO ABOVE TO WELL ABOVE NORMAL
TEMPERATURES ON THURSDAY. LOWS TUESDAY AND WEDNESDAY AM MAY STILL
NEED TRIMMING WITH GOOD RADIATIONAL COOLING CONDITIONS. THURSDAY
SHOWS GOOD SOUTH WINDS WITH LOW LEVEL THERMAL FIELDS SUGGESTING MAX
TEMPS MAY NEED RAISING AT LEAST 5 DEGREES HIGHER FOR LATER SHIFTS.
ALSO GUSTY WINDS MAY ALSO BE IN STORE.
FRIDAY AND SATURDAY...EVIDENCE WITH SW UPPER FLOW AND MODERATE SIZE
UPPER TROUGH OF A SEASONALLY MODERATE TO HIGH END PRECIPITATION
EVENT BUT TIMING STILL A QUESTION. KEPT POPS LOW ATTM WITH NEAR TO
SLIGHTLY ABOVE NORMAL TEMPERATURES. TIMING AND STRENGTH OF EVENT
STILL A COUPLE DAYS AWAY. ..NICHOLS..
AVIATION
VFR CONDITIONS WILL PREVAIL OVERNIGHT INTO SUNDAY. 5 TO 10 KT WINDS
WILL CONTINUE TO VEER TO THE NORTHWEST THIS EVENING...THEN BECOME
LIGHT NORTHEAST TO EAST BY MORNING. THERE IS A POTENTIAL FOR A FEW
HOURS OF MVFR VISIBILITIES AROUND SUNRISE AT HAVE HANDLED WITH TEMPO
GROUPS IN FORECASTS. HAVE ALSO BROUGHT IN POTENTIAL FOR A PERIOD OF
MVFR CIGS IN THE BRL AREA AROUND SUNRISE. WINDS WILL INCREASE TO 10
KTS FROM THE SOUTH SUNDAY MORNING AS A WARM FRONT ADVANCES NORTH
THROUGH THE AREA. ..SHEETS..
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHEETS/NICHOLS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page