Flash Flood Warning 20, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
302 PM CDT MON JUL 10 2000

18Z SURFACE ANALYSIS HAS TWO WEAK LOWS ALONG THE FRONT...ONE NEARING
KDSM AND THE OTHER NORTHEAST OF KCNK. THE FRONT RUNS FROM THE FIRST
LOW TO NEAR KCID AND THEN TOWARD FAR SOUTHEAST WISCONSIN SOUTH OF
KMKE. OUTFLOW BOUNDARY IS JUST SOUTH OF THE FRONT RUNNING FROM ABOUT
KAWG TO KCHI. SURFACE RIDGE RUNS FROM THE ARROWHEAD OF MINNESOTA TO
SOUTH OF KPIR AND THEN INTO SOUTHEAST COLORADO. VISIBLE IMAGERY
SHOWS CI DEBRIS FROM MORNING CONVECTION OVER THE AREA WITH SOME AC.
TCU AND SMALL CBS ARE DEVELOPING ALONG THE OUTFLOW BOUNDARY WITH IR
INDICATING COOLING TOPS. WATER VAPOR AND PROFILER DATA INDICATE A
CIRCULATION AT H85 IN SOUTHWEST IOWA WITH ANOTHER SHORTWAVE IN
EASTERN NEBRASKA AT H5. TROPICAL CONNECTION CONTINUES UP THROUGH THE
ROCKIES WITH MONSOONAL MOISTURE AND LIGHTNING DATA INDICATING
CONVECTION ALREADY UNDERWAY. ONE ADDITIONAL SHORTWAVE IS MOVING FROM
NORTHWEST MEXICO INTO NEW MEXICO/ARIZONA AREA. REGIONAL RADAR SUMMARY
SHOWS CONVECTION DEVELOPING AS WELL ACROSS SOUTHERN IOWA. MOISTURE
ANALYSIS HAS LOW TO MID 70 DEW POINTS ACROSS THE AREA THAT QUICKLY
DROP INTO THE MID AND UPPER 60S BEHIND THE TRUE FRONT IN WISCONSIN.

PROBLEMS THIS PACKAGE ARE USUAL CLOUDS/TEMPS WITH THE ADDITION OF
PRECIP TIMING...SEVERE POTENTIAL...AND HEAVY RAIN.

12Z MODELS INITIALIZED FAIRLY WELL IN REGARDS TO THE SYNOPTIC SCALE
BUT HAD PROBLEMS AT THE MESOSCALE WHICH IS QUITE EVIDENT AT 18Z.
MODELS ARE HAVING TROUBLE RESOLVING THE FRONT AND OUTFLOW BOUNDARY
...AND THUS MELD THEM TOGETHER AND FURTHER SOUTH. NONE OF THEM ARE
CATCHING THE MESO CIRCULATION ACROSS IOWA BUT THE AVN HINTS AT THE
SHORTWAVE INTO EASTERN NEBRASKA. SURFACE MOISTURE IS NOT BEING
HANDLED WELL EITHER. ETA NOT BAD IN SPOTS AND SAME WITH AVN.
THEREFORE WILL USING A MIX MATCH OF THE MODELS FOR THIS FORECAST.

IN THE NEAR SHORT TERM CONCEPTUAL MODELS AND TRENDS FROM 18Z RUC
INDICATE TRUE FRONT TO SLOWLY SINK SOUTH. NATURAL CONVERGENCE ALONG
THE OUTFLOW BOUNDARY TO PROVIDE THE FOCUS FOR THE NEXT ROUND OF TSRA
DEVELOPMENT...MAINLY ACROSS THE SOUTHERN PART OF THE FORECAST AREA.
PLENTY OF JUICE TO WORK WITH SO AREAS ALONG/SOUTH OF HIGHWAY 34
SHOULD HAVE THE BEST CHANCES OF PRECIP TONIGHT. SEVERE POTENTIAL
THERE GIVEN INSTABILITY SO WILL HAVE TO WATCH TRENDS CLOSELY.
NORTHERN TWO THIRDS OF FORECAST AREA WILL GO LOW POP CHANCES WITH
IDEA ANY PRECIP TO BE ISOLATED. MODELS SOMEWHAT SUPPORT THIS WITH
SOME QG FORCING AND INITIAL AREAS OF LOWER CONDENSATION PRESSURE
DEFICITS.

TUESDAY FRONT SHOULD HAVE MOVED SOUTH OF THE AREA WITH NICE EASTERLY
FLOW. DEW POINTS SHOULD BE SOMEWHAT LOWER AS WELL AS TEMPERATURES.
MODELS INDICATE DOWNWARD MOTION WITH SOME MOISTURE TRAPPED SO
DIURNAL CU SHOULD DEVELOP AS IT DID TODAY IN WISCONSIN. TUESDAY
NIGHT/WEDNESDAY MORNING IS THE BIG QUESTION. MODELS SHOW FRONT
MOVING BACK NORTH WITH A REASONABLE LLJ IN THE PLAINS. GOOD QG
FORCING SO EXPECT ANOTHER MCS TO FIRE IN THE PLAINS AND MOVE ACROSS
IOWA. SHORTWAVE MOVING INTO ARIZONA/NEW MEXICO IS THE LIKELY
INITIATOR FOR THIS MCS. HEAVY RAIN A THREAT AS WELL. WILL NOT ISSUE
ANY HEADLINES BUT WILL ISSUE ESF TO RAISE AWARENESS TO THE
SERIOUSNESS OF THE SITUATION. PRECIP TO LIKELY CONTINUE FOR A GOOD
CHUNK OF WEDNESDAY AND IF A GOOD COLD POOL DEVELOPS...TEMPERATURES
WOULD BE QUITE COOL. DEPENDING ON HOW QUICK MCS MOVES...PRECIP MAY
OR MAY NOT CONTINUE INTO WEDNESDAY EVENING. FOR NOW WILL LEAVE DRY
AND MODELS WOULD SUPPORT THIS WITH STRONG DOWNWARD MOTION.

EXTENDED WISE...WILL CONTINUE WITH CONTINUITY AND KEEP CHANCE POPS
IN FOR THURSDAY. FRIDAY/SATURDAY LOOK TO BE DRY.

FWC/FAN/MAV NUMBERS SHOWING CONSIDERABLE DIFFERENCES IN
TEMPERATURES. ATTM LEANING TOWARD USING THE COOLER FAN NUMBERS.

COORDINATED WITH DSM..LSE...CHI...ILX...AND STL.

.DVN...NONE.

TI

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