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000
FXUS63 KDVN 111739
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1239 PM CDT SAT MAY 11 2013

.SYNOPSIS...
ISSUED AT 257 AM CDT SAT MAY 11 2013

UPPER LEVEL LOW OVER CENTRAL CANADA INTO THE NORTHERN PLAINS AND
UPPER MIDWEST IS SPINNING A SHORT WAVE TROUGH ACROSS SOUTHERN MN
WHICH IS PROGRESSING EAST SOUTHEAST INTO NORTHERN IA AND WESTERN
WI. AT 08Z...A COLD FRONT IDENTIFIED BY A SHARP WIND SHIFT AND
INCREASE IN WIND SPEEDS WAS LOCATED ROUGHLY FROM MASON CITY TO
BOONE TO DENISON. ONLY VERY LIGHT SPOTTY RAIN WAS ASSOCIATED WITH
THE IOWA PORTION OF THE FRONT...THOUGH A BROADER COVERAGE OF RAIN
WAS OBSERVED TO THE NORTH WHERE UPPER LEVEL SUPPORT IS STRONGER.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 257 AM CDT SAT MAY 11 2013

MAIN CONCERN TODAY IS TIMING THE FRONTAL PASSAGE AND TONIGHT THE
POTENTIAL FOR PATCHY FROST AND LOCALIZED NEAR FREEZING TEMPERATURES.

MODEL CONSENSUS THIS MORNING AND EXTRAPOLATION FROM CURRENT TRENDS
BRINGS THE COLD FRONT TO THE MISSISSIPPI RIVER BETWEEN 12-14Z AND
THEN EXITS THE CWA BY 18Z. GENERALLY MID CLOUDS OR HIGH-BASE LOW
CLOUDS ARE ASSOCIATED WITH THE PORTION OF THE FRONT HEADING
TOWARD OUR CWA... SUGGESTING ONLY SCATTERED SPRINKLES. HAVE A
BRIEF PERIOD OF LOW POPS WITH THE FRONTAL PASSAGE..BUT DRY AND
WINDY CONDITIONS WILL PREVAIL OVERALL TODAY. 850MB COLD AIR
ADVECTION WILL HELP COUNTER MAY SUNSHINE WITH MAX TEMPS NOT TOO
DISSIMILAR FROM YESTERDAYS HIGHS.

SURFACE HIGH PRESSURE AND DRIER AIR MOVE INTO THE AREA OVERNIGHT.
WEAK GRADIENT WILL LIKELY KEEP WINDS UP SUFFICIENTLY HIGH TO KEEP
TEMPS FROM REALLY BOTTOMING OUT...BUT SHELTERED AREAS COULD SEE
PATCHY FROST AND NEAR FREEZING TEMPS...ESPECIALLY TO THE NORTH AND
WEST OF THE QUAD CITIES. MOIST GROUND WILL ALSO HELP KEEP MIN
TEMPS UP A BIT.  WOLF

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 257 AM CDT SAT MAY 11 2013

TEMPERATURES REMAIN THE MAIN CONCERN FOR SUNDAY THROUGH
TUESDAY...FOLLOWED BY PRECIPITATION CHANCES THROUGH THE END OF THE
WEEK.

SUNDAY TO REMAIN COOL AND DRY WITH NORTHWEST FLOW CONTINUING TO
BRING IN THE STRONG SURFACE RIDGE WITH ITS DRIER AND COLDER
AIR MASS.  HIGHS ON SUNDAY WILL ONLY RANGE FROM THE MID 50S NORTH TO
AROUND 60 SOUTH AFTER THE VERY COLD START TO THE DAY.  THIS SETS THE
STAGE FOR ANOTHER COLD NIGHT SUNDAY NIGHT.  THIS TIME...WE WILL HAVE
LIGHTER WINDS WITH THE RIDGE SHIFTING OVER AND JUST EAST OF THE
FORECAST AREA OVERNIGHT.  HOWEVER...AT 850MB WARM AIR ADVECTION WILL
BE ONGOING ALL NIGHT...ALONG WITH SOME MOISTURE ADVECTION AS WELL.
THIS COMBINED WITH SOME AIR MASS MODIFICATION GOING ON WITH THE EARLY
MAY SUNSHINE ON SUNDAY.  SOME OF THESE THINGS WILL JUST OFFSET EACH
OTHER AND EXPECT VERY SIMILAR MIN TEMPS TO WHAT WE WILL HAVE
TONIGHT.  WILL HAVE TO WATCH THIS SITUATION CAREFULLY...AS WE MAY
NEED A FROST ADVISORY FOR SUNDAY NIGHT.  HAVE PUT PATCHY FROST IN
THE FORECAST FOR NOW.

MONDAY AND MONDAY NIGHT THE WARM MOIST AIR ADVECTION GETS GOING
ALOFT.  SOME MODELS ARE BRINGING A WING OF WARM AIR ADVECTION
PRECIPITATION ACROSS THE AREA MONDAY AFTERNOON AND EVENING.  HAVE
SOME DOUBTS ABOUT THE MOISTURE AVAILABILITY...THOUGH THE WARM AIR
ADVECTION WILL BE STRONG.  FOR NOW HAVE INCLUDED SOME SLIGHT CHANCES
IN OUR NORTHEAST FOR THE AFTERNOON AND EVENING.

ALL THIS WARM AIR ADVECTION SHOULD BRING SOME VERY WARM TEMPERATURES
OVER THE AREA AT 850MB ON TUESDAY...WITH MOST MODELS SURGING 850MB
TEMPERATURES OF 20-24C OVER THE AREA BETWEEN 18Z AND 00Z.  THE
MODELS ARE ALSO SURGING VERY WARM SURFACE TEMPS AND DEW POINTS INTO
THE AREA AS WELL.  SOME ARE GOING OVERBOARD WITH THE
DEW POINTS...BRINGING MID JULY DEW POINTS IN THE LOW 70S INTO THE
AREA.  IN IOWA...LESS THAN 10 PERCENT OF THE CORN CROP IS EVEN
PLANTED...WHICH MEANS WE ARE NOT GOING TO HAVE A BIG
EVAPOTRANSPIRATION BOOST THAT WE MIGHT NORMALLY BE BEGINNING TO GET
BY THIS TIME OF YEAR.  IN FACT...THE CORN PLANTING IS DELAYED ALL
OVER THE MIDWEST THIS YEAR...SO EVEN IN KANSAS AND MISSOURI THE CORN
IS NOT AS FAR ALONG AS IT WOULD NORMALLY BE. SO THIS REALLY THROWS
DOUBT ON ANY DEW POINT HIGHER THAN THE MID 60S.  WE HAVE TO GO TO THE
GULF COAST BEFORE WE CAN FIND DEW POINTS IN THE UPPER 60S TO LOW 70S
IN THE LAST 24 HOURS.  OUR VERY WET SOILS RIGHT NOW ARE GOING TO
CONTRIBUTE SOME MOISTURE...BUT NOT AS MUCH AS A GROWING CORN CROP
WOULD.  THE HIGHER DEW POINTS DEPICTED BY THE MODELS ARE ACCOMPANIED
BY A LOW LEVEL INVERSION AND COOLER TEMPERATURES ON TUESDAY.
HOWEVER THIS DOES NOT MAKE CONCEPTUAL SENSE...AS WOULD EXPECT A DEEP
MIXING DAY WITH A DEEP DRY ADIABATIC LAYER AND BREEZY SOUTH WINDS ON
THE SOUTH SIDE OF THE WARM FRONT WHICH MOVES NORTH ACROSS THE AREA
LATE MONDAY NIGHT OR TUESDAY MORNING.  THUS...HAVE BOOSTED MAX TEMPS
ON TUESDAY INTO THE MID TO UPPER 80S.  PURE MIXING TECHNIQUES IMPLY
THAT EVEN LOW 90S ARE POSSIBLE...BUT WILL HOLD OFF GOING THAT FAR
ABOVE GUIDANCE FOR NOW.  FYI...RECORD HIGHS FOR TUESDAY ARE IN THE
LOW 90S.  THE WARM AIR REMAINS THROUGH TUESDAY NIGHT WITH MIN TEMPS
IN THE 60S.

WEDNESDAY OUR SITUATION CHANGES AS THE SAME LOW PRESSURE SYSTEM THAT
PUMPED ALL THE WARM AIR INTO THE AREA SENDS A COLD FRONT SURGING IN
TO THE AREA WEDNESDAY AND WEDNESDAY EVENING.  THE TIMING OF THIS FRONT
PRODUCES SOME CONCERNS FOR STRONG TO SEVERE THUNDERSTORMS SOMEWHERE
IN OR AROUND THE FORECAST AREA WEDNESDAY AFTERNOON AND EVENING.
MUCH IS GOING TO DEPEND ON THE EVENTUAL TIMING OF THE FRONT...HOW
WARM WE GET AHEAD OF THE FRONT AND HOW HIGH THE DEW POINTS ACTUALLY
GET OVER THE AREA AHEAD OF THE FRONT.  FOR NOW HAVE GONE WITH
CONSENSUS HIGHS RANGING FROM AROUND 80 TO THE MID 80S.  THE DEW POINT
CONCERNS I MENTIONED ABOVE REMAIN FOR WEDNESDAY...BUT THEY ARE
LIKELY TO BE HIGHER THAN TUESDAY WITH THE CONVERGENCE ALONG AND
AHEAD OF THE FRONT.  WE MAY ALSO HAVE SOME SHEAR TO WORK WITH AS THE
UPPER LEVEL JET MOVES ACROSS MN AND WI.  THERE IS STILL MUCH TO
RESOLVE ON THIS SYSTEM BUT FOR NOW WILL MENTION THE POTENTIAL FOR
STRONG THUNDERSTORMS WEDNESDAY IN THE HWO.  AM CARRYING SOME SLIGHT
TO SMALL CHANCE POPS WEDNESDAY AND WEDNESDAY NIGHT FOR NOW...AND
WILL HAVE TO SEE HOW THINGS SET UP WITH LATER RUNS.

THURSDAY WE CONTINUE TO HAVE PRECIPITATION CHANCES WITH THE FRONT
NEARBY...WITH SEASONABLE TEMPERATURES.  BY FRIDAY THIS FRONT SHIFTS
BACK NORTH AND WE BEGIN TO GET INTO ANOTHER WARM SECTOR AS A NEW
SYSTEM BREWS OUT IN THE PLAINS.  SATURDAY COULD BE ANOTHER WELL
ABOVE NORMAL DAY.   LE

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1233 PM CDT SAT MAY 11 2013

STRONG WAND GUSTY NORTHWEST WINDS OF 20 TO 30 KTS WITH A FEW HIGHER
GUSTS WILL DIMINISH BETWEEN 11/22Z AND 12/02Z TO LESS THAN 10 KTS.
FAIR SKIES WILL CONTINUE TONIGHT AND TOMORROW AS HIGH PRESSURE
OVER THE DAKOTAS MOVES SOUTHEAST. WINDS WILL INCREASE WITH DAYTIME
HEATING AFTER 15Z TO 10 TO 20 KTS...AGAIN OUT OF THE NORTHWEST.

NICHOLS

&&

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

$$

SYNOPSIS...WOLF
SHORT TERM...WOLF
LONG TERM...LE
AVIATION...NICHOLS