[LeArc] Forecast Discussion : MLI@ 3/15/03 1:22:27 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 151930
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
125 PM CST SAT MAR 15 2003

.OVERVIEW...DEJA VU...LOW CLOUDS AND FOG THIS AM SIMILAR TO FRIDAY/S
EVENT.  PRIME REASON IS OUR COLD GROUND AND RESIDUAL MOISTURE FROM
SNOW MELT.  SURFACE ANALYSIS AND SATELLITE TRENDS SHOW LOW CLOUDS TO
AGAIN DISSIPATE 19-20Z.  HIGHER DEWPOINTS CONTINUE TO MOVE INTO
AREA...SO SEE NO REASON NOT TO HAVE ANOTHER ROUND OF LOW CLOUDS AND
FOG TONIGHT WITH MIN TEMPS 1-2 CATEGORIES BELOW GUIDANCE. UPPER AIR
SHOWS CONTINUED WAA WITH SOME MID AND HIGH LEVEL MOISTURE TO ARRIVE
NEXT 24 HOURS BUT LIKELY TO HAVE MINOR IMPACTS ON RADIATIONAL COOLING
AND FOG CHANCES TONIGHT. ADVERTISED PACIFIC STORM JUST NOW ARRIVING
ON COAST.

...FOG CHANCES TONIGHT WITH IMPACT ON TEMPS NEAR TERM ISSUE WITH
LARGE BUT SLOW MOVING STORM SYSTEM NEXT WEEK LONGER CHALLENGE...

.DIAGNOSIS AND DAYS 1-3...FOR SECOND DAY IN A ROW MODELS DOING VERY
POORLY ON TEMPS ACROSS AREA AT 18Z (OFF BY 10-15 DEGREES AND ETA 2M
TEMPS UP TO 25 DEGREES TOO WARM) DUE TO FOG AND LOW CLOUDS.  UKMET SFC
TEMPS DEFINITELY BEST AT 18Z AND THEY CONTINUE TO SUGGEST LOW CLOUDS
INTO LATE MORNING AND THUS COOLER HIGHS FOR SUNDAY.  SO USE PERSISTENCE
HEAVILY TONIGHT AND TOMORROW BLENDED WITH UKMET AS MENTIONED ABOVE WITH
EVEN HIGHER DEWPOINTS COMING ON COLD GROUNDS AND LITTLE MAJOR FORCING TO
MIX AIR OVERNIGHT.  THUS WILL LOWER HIGHS SUNDAY AT LEAST 2-3 CATEGORIES
TO LOWER SIDE OF GUIDANCE DUE TO MORE CLOUDS. KEEP CHANCE OF SHRA AND
TSRA BUT SEVERE CHANCES MUCH LOWER DUE TO COLDER TEMPS. GFS-AVN NOW
TRENDING SOUTH SOLUTION IN LINE WITH MORE CONSISTENT PAST RUNS OF UKMET
AND ETAX. THUS LATE SUNDAY AND ESPECIALLY FOR MONDAY CHANCE OF SHOWERS
AND STORMS WITH BACK-DOOR COLD FRONT FROM LAKE MICHIGAN WHICH WILL BE A
BIG CHALLENGE ON TEMPS. SHOULD HAVE BETTER IDEA ON STRENGTH OF LAKE
EFFECT SUNDAY BUT FOR NOW APPEARS ANOTHER 20+ DEGREE GRADIENT MONDAY
HIGHS WITH LOW CLOUDS AND FOG ALONG WITH PRECIPITATION...ESPECIALLY
NORTH OF I-80. THEN KEEP LIKELY POPS THROUGH TUESDAY WITH OVERRUNNING AS
UPPER LOW APPROACHES. MINOR CHANGES TO TUESDAY TEMPS AS LATEST MIX OF
MODEL NOW IN LINE WITH EARLIER REASONING.   KEY ITEM AGAIN TO PASS TO
LATER SHIFTS IS POTENTIAL FOR DENSE FOG ADVISORY.

.EXTENDED (WED-SAT)...RAISE POPS TO LIKELY WEDNESDAY WITH SURFACE LOW
WAVE AND MODERATE TO HEAVY RAINS STILL REASONABLE.  STILL APPEARS
MOST AREAS TO RECEIVE AROUND AN INCH OR MORE OF RAIN BY WEDNESDAY
NIGHT WITH LOCALLY HIGHER AMOUNTS.  SLOWER PROGRESSION OF SYSTEM PER
UKMET/GFS-AVN SUGGEST RAISING TEMPS THU/FRI TIL WINDS BECOME NW AND
KEEPING CHANCE POPS OF RAIN IN WRAPAROUND MOISTURE.

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

$$

NICHOLS