FXUS63 KLOT 191226
AFDCHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO IL
730 AM CDT SAT APR 19 2003

UPDATED AVIATION DISCUSSION

WILL BE AMENDING TAFS TO ADD NONCONVECTIVE LLWS THIS AM BASED ON VWP 
FROM LOT 88D. 

JHV

DISCUSSION FOR 12Z TAFS...
TSRA IN SE WI AND XTRM NE IL TO CONT TO MOV NNE WITH THETA E ADV 
MAX. LRG TSRA COMPLEX IN OK AND ERN KS WILL MOV NE TO IA AND NW IL 
22-00Z AS MID LVL LOW OVR TX AND OK PANHANDLES MOVES NE ACROSS KS. 
EXPECT TSRA TO DEVELOP FURTHER E IN IL MID AFTERNOON WITH INCREASING 
INSTABILITY DUE HEATING AND DEW PTS INCREASING INTO 50S.    

TRS


145 AM CDT SAT APR 19 2003
DISCUSSION FOR MORNING GRIDS & ZONES...

MODELS TENDING TO BLEND TOGETHER BETTER WHICH RESTORES SOME 
CONFIDENCE IN WHAT TO EXPECT THIS WEEKEND. CYCLOGENESIS IN PLAINS 
COMING ALONG FINE WITH FIRST SHORT WAVE SWINGING THRU ERN IA. SOME 
WEAK SHOWERS IN IL DISSIPATING TO SPRINKLES OR DISSOLVING ALTOGETHER 
IN 30 DEWPT AIR. DEWPTS PROGGED TO INCREASE INTO 50S TODAY WITH 
CONTD SLY FLOW WHICH SHUD SUPPORT SOME TSTM ACTIVITY ESP WEST OF IL 
RTE 51 TODAY.

BEST ACTIVITY IN IOWA MOVING FASTER TO THE NORTH THAN EAST WHICH 
GIVES MORE CREDENCE TO THE ETA OVER GFS THRU FIRST 24 HRS. THESE 
STORMS IN TONGUE OF HIER THETA E WHICH IS PROGGED ON ETA TO REACH 
RFD AREA NEAR DAYBREAK...WRIGGLING INTO CHI THIS AFTN. STORMS IN ERN 
IA LIKELY TO CROSS OVER MS RIVER BEFORE 3AM...ENCOUNTERING THAT 
DRIER IL AIR. WILL SEE IF ITS SURVIVAL PERSISTS. OF COURSE WILL HAVE 
TO GO FOR SHOWERS AND TSTMS LIKELY TODAY IN EXPECTATION OF INCREASED 
RH AND THAT DRIVING THETA E RIDGE TIMED TO MOVE THRU IL DURING 
DAYTIME HEATING. SO BEST CHC OF SVR WX WILL BE TODAY IN IL. MUCH OF 
THIS SVR POTENTIAL AIDED BY SUNSHINE. THIS APPEARS TO BE FADING 
CONSIDERING DEBRIS CLOUDINESS FROM IOWA STORMS...NOT TO MENTION 
MASSIVE CIRRUS OUTPUT RIDING THIS WAY FROM DEVELOPING STORMS IN SRN 
PLAINS.
 
THETA E RIDGE SLIPS INTO NWRN IN TNGT BUT DAYTIME HTG GONE THEN 
JUST AS DRY INTRUSION SLIPS THRU IL. BY DAYBREAK SUNDAY THE COLD 
FRONT APPROACHES THE MS RIVER WITH SFC LOW KICKING OUT ACROSS NRN 
WI. ANOTHER CHC OF TSTMS WITH FROPA BUT MAIN THREAT OF SEVERE WX OFF 
TO ERN IN/WRN OHIO WHERE THETA E RIDGE ABIDES.

BACKWASH PCPN SWINGING THRU SUN NGT THRU MONDAY NGT AND PSBLY TUES 
MRNG. WHILE MODELS INDICATING 850 TEMPS BLO ZERO TUES MRNG...WUD 
SHOW SOME PRUDENCE TO WITHOLD MENTION OF SNOW...ALTHO THIS NOT 
UNHEARD OF EVEN INTO LATE MAY.

SHUD BE DRY REST OF WEEK WITH RETURNING COOLING ANTICYCLONIC FLOW 
UNDER TEMPORARY OMEGA BLOCK JUST W OF MS RVR. 

NOT A BIG VARIABILITY IN TEMPS AFT MAX TEMP TODAY AS CONTD SRLY FLOW 
KEEPS DEWPTS HIGH AND WAA PUMPING. AFTER FROPA SUNDAY...LOWS GOING 
BACK DOWN TO 40S WITH MAINLY 50S FOR HIGHS XCP SOME LOW 60S FAR 
SOUTH IN CWFA.

.CHI...NONE

BRUMER