Severe Thunderstorm Warning 191, NWS Quad Cities, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
220 PM CST WED NOV 1 2000

.OVERVIEW...MODERATELY STRONG CLOSED LOW NOW OVER WESTERN NORTH
DAKOTA IS LIFTING NORTH OUT OF LONG WAVE TROUGH.  BROKEN AREA OF
SHOWERS AND THUNDERSTORMS NOW EXTENDS ALONG AND AHEAD OF FRONT FROM
NEAR KMSP TO NEAR KMCI.  SOUTH WINDS OVER FORECAST AREA COMBINED
WITH PARTLY SUNNY SKIES ARE ALLOWING TEMPERATURES TO RISE INTO THE
75 TO 80 DEGREE RANGE BY 19Z.  SURFACE DEWPOINTS OVER AREA NOW IN
THE LOWER 60S TO PROVIDE FUEL FOR APPROACHING COLD FRONT.  LATEST 18Z
SURFACE ANALYSIS SHOWS SURFACE LOW NEAR KRAP WILL CONTINUE TO
INTENSIFY AND MOVE NORTH NORTH CENTRAL DAKOTA.

...ASSESSING CHANCES OF PRECIP TONIGHT AND THEN COOL DOWN MAIN
CHALLENGE...

.DIAGNOSIS AND NEAR TERM...MODELS VERIFY WELL AT 18Z WITH ETA
DEFINITELY THE BEST ON SMALLER SCALE FEATURES AND LOW LEVEL MOISTURE
...BUT NGM BEST AND THEN AVN ON SD SURFACE LOW AND ASSOCIATED SFC TROUGH
INTO TX.  BECAUSE OF THIS WILL USE BLEND OF QPF AMOUNTS FROM NGM/AVN
WITH DRIER ETA.  TIMING SUGGESTS BROKEN PRECIP TO MOVE ACROSS AREA
BETWEEN 22Z AND 14Z IN THE FORM OF AREAS OF SHOWERS AND SOME
THUNDERSTORMS. WARMER TEMPS AND HIGHER DEWPOINTS...COMBINED WITH A LOW
LEVEL JET OF 30 TO 40 MPH MAY ALLOW FOR SOME STRONG STORMS WITH AN
ISOLATED SEVERE REPORT POSSIBLE...MAINLY IN THE FORM OF STRONG WINDS
WITH HAIL A SECONDARY THREAT WEST OF RIVER.  ANY SEVERE THREAT...HOWEVER
LIMITED SHOULD DIMINISH BY MID EVENING AS ATMOSPHERE COOLS AND FRONT
SLOWS DOWN REDUCING LOW LEVEL FORCING. FOR LOWS TONIGHT...WILL GO WITH
CLOUDS AND PRECIP NEARER TO WARMER FWC. SOUTH WINDS WILL ALSO ONLY
DIMINISH TO 10 TO 15 MPH WITH SOME HIGHER GUSTS TO KEEP AIR MIXED.  WILL
GO CHANCE POPS WELL EAST OF MISS. RIVER AND LIKELY POPS OR 80 PERCENT
REST DEPENDING ON NOWCAST TOOLS. TOMORROW WILL SEE RAPID CLEARING BEHIND
FRONT WITH NOSE OF 115+ KT JET IMPINGING WITH ASSOCIATED DRY SLOT.  EAST
OF RIVER WILL KEEP CHANCE POPS EARLY BEFORE CLEARING AND NEAR STEADY
TEMPS AS GOOD CAA OCCURS. WEST DOWNSLOPE WINDS OF 10 TO 20 MPH WILL GO
AT HIGH OF HIGHS WITH NEARLY STEADY TEMPERATURES BY PM.

.DAY 2...HIGH PRESSURE SETTLES JUST SOUTHWEST OF REGION TO PRODUCE
WEST WINDS AT 10 TO 15 MPH...QUIET WEATHER AND SIGNIFICANTLY COOLER
TEMPERATURES TO NEAR SEASONABLE READINGS. WILL GO WITH HIGH TEMPS
CLOSE TO MAV GUIDANCE. SOME FAIR WEATHER STRATOCUMULUS CLOUDS TO
DEVELOP...ESPECIALLY ALONG AND NORTH OF I-80 DUE TO CYCLONIC FLOW.

EXTENDED (SAT-MON)...ALL 6 MEDIUM RANGE MODELS VARY QUITE A BIT ON
DEVELOPING TROUGH BY DAY 5.  EACH SOLUTION SUPPORTS CHANCE OF RAIN
LATE SUNDAY AND EITHER CHANCE OR LIKELY POPS WARRANTED FOR MONDAY.
DEPENDING ON SOLUTION SUCH AS CANADIAN AND MRF...COULD SEE HEAVY
RAINS.  WILL BE CONSERVATIVE DUE TO TEMPORAL AND MODEL VARIANCE AND
PUT CHANCE POPS IN FOR DAY 5 WITH MINOR CHANGES ELSEWHERE.  TEMPS
WILL FAVOR MEX GUIDANCE gADJUSTED FOR CLOUD COVER.

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

NICHOLS