Severe Thunderstorm Warning 166, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
145 PM CST SAT DEC 22 2001

MODELS ARE ON TRACK SO FAR AS SYSTEM EVOLVES OVER CENTRAL U.S.
SURFACE LOW CURRENTLY REFORMING OVER SOUTHERN MINNESOTA WITH COLD
FRONT EXTENDING SOUTH THROUGH CENTRAL IA INTO WESTERN MO.  SHRA...AHD
OF S/W MOVING THROUGH WRN IA/NW MO...COVERS MUCH OF CWA NORTH OF I-
80 AND SHOULD LIFT NORTH OUT OF AREA THIS AFTERNOON  MEANWHILE
SHRA/TSRA CONITINUES TO DEVELOP AHEAD OF FRONT OVER SCENTRAL IA AND N
CENTRAL MO.  H5 LOW DROPPING SOUTH ACROSS THE DAKOTAS THIS MORNING IS
VERY EVIDENT ON THE WATER VAPOR IMAGERY. MODELS MOVE THIS SYSTEM
ALONG IA/MO BORDER TONIGHT THEN LIFT IT NE INTO THE GREAT LAKES
SUNDAY WHERE IT TAKES UP RESIDENCE FOR THE NEXT SEVERAL DAYS.

THE ARE PLENTY OF CONCERNS FOR THE NEXT 36 HOURS RANGING FROM
CONVECTION LATE THIS AFTERNOON AND EVENING SOUTH AHEAD OF
THE FRONT...INTRUSION OF MUCH COLDER AIR THIS EVENING AND PCPN/PCPN
CHANGE OVER...THEN SNOW CHANCES/AMOUNTS SUNDAY AS H5 LOW LIFTS INTO
GREAT LAKES.  BREAK IN CLOUD COVER OVER SOUTHWESTERN CWA HAS
ALLOWED SURFACE TEMPS TO WARM INTO THE MID 50S OVER SWRN CWA AS OF
19Z.  STORMS IN DMX CWA PRODUCING SOME HAIL ATM.  WILL HAVE TO KEEP
AN EYE ON TSRA AS IT MOVES INTO SLIGHTLY MORE UNSTABLE AIR LATE
THIS AFTERNOON AND EARLY THIS EVENING.  WILL INCLUDE THUNDER FOR
EARLY EVENING ALONG AND EAST OF THE RIVER AS FAR NORTH OF I80 PER
LATEST 15 MIN LIGHTNING STRIKE GRAPHICS.  COLD FRONT WILL CROSS
MISSISSIPPI RIVER AROUND 00Z.  TEMPS BEHIND FRONT WILL DROP INTO THE
UPPER 20S TO LOWER 30S BY 06Z.  AT THIS POINT IT LOOKS LIKE MOST OF
THE PCPN WILL BE OVER WITH BEFORE THE COLD AIR MOVES IN BUT WILL KEEP
LOW POPS GOING TONIGHT FOR -SN SINCE THE SYSTEM IS SO DYNAMIC.  AS H5
LOW LIFTS NORTHEAST SUNDAY AVN/ETA SUGGESTING THAT DEF ZONE WILL SET
UP AROUND MID DAY OVER NORTHERN CWA.  IT DOESNT LOOK LIKE THERE WILL
BE MUCH DEEP MOISTURE AVAILABLE AND FORCING...BASED ON Q VECTORS AND
FRONTOGENESIS FIELDS...WILL BE WEAK. BELIEVE NORTHERN SECTIONS
COULD SEE AROUND AN INCH BY EARLY EVENING WITH JUST A DUSTING SOUTH.
WITH CLOUDS AND -SN AROUND SUNDAY AND SOME CAA...TEMPS WONTT CHANGE
MUCH DURING THE DAY AND WILL ALLOW FOR ONLY A 5 DEGREE RISE.  AFTER
SUNDAY EVENING...CONCERN WILL BE TEMPS AND -SN WITH STRONG CYCLONIC
FLOW OPENING THE DOOR FOR FIRST ARCTIC OUTBREAK OF THE SEASON.  LOOKS
AS IF MOST OF THE MOISTURE WILL BE IN THE LOW LEVELS SO WILL CONTINUE
FLURRY WORDING MONDAY AND MONDAY NIGHT.  LOBE OF ENERGY ROTATING
AROUND GREAT LAKES LOW WILL PROVIDE A CHANCE OF SOME LIGHT SNOW
CHRISTMAS DAY.  TEMP FORECAST WILL FAVOR COLDER MAV NUMBERS.

EXTENDED...WEDNESDAY THROUGH SATURDAY
MODELS AGREE IN THE OVERALL PICTURE KEEPING REGION IN NORTHERLY FLOW
THROUGH THE WEEK WITH SHARP RIDGE OVER WESTERN U.S. AND DEEP H5 LOW
PINWHEELING OVER NORTHERN GREAT LAKES BEFORE HEADING EAST BY LATE
WEEK.  NO DOUBT ITS GOING TO BE ...COLD... SO MAIN PROBLEM WILL BE
NARROWING DOWN ANY SNOW CHANCE FOR MID TO LATE WEEK.  WITH CYCLONIC
FLOW OVER REGION AND HIGH LOW LEVEL RH WE SHOULD HAVE AT LEAST
FLURRIES MOST DAYS.  WILL TIE SNOW CHANCES TO LOBE ROTATING AROUND
GREAT LAKES LOW WEDNESDAY THEN AGAIN THURSDAY AND FRIDAY WITH ANOTHER
SURGE OF COLD AIR MOVING IN.  MEX TEMPS GENERALLY ACCEPTED...EXCEPT
FOR FRIDAY/SATURDAY.  MRF BRINGING IN COLDEST AIR THUS FAR FOR THE
EVENT AND WILL STAY 5 TO 10 DEGREES BELOW MEX NUMBERS.  ANOTHER
FACTOR WILL BE SNOW FIELD TO OUR NORTH AFTER TODAY WHICH WILL KEEP
AIR MASS FROM MODERATING.

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

DLF