[LeArc] Forecast Discussion : MLI@ 2/16/03 1:53:12 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 162002
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 PM CST SUN FEB 16 2003

SFC AND UPPER RIDGING TO BRING ABOUT FAIR WX TONIGHT THROUGH MON...
BEFORE PACIFIC ENERGY(NOW SEEN ON W/V IMAGERY PUNCHING INTO THE
NORTHWEST CONUS COAST) SKIRTS ACRS THE UPPER MS RVR VALLEY MONDAY
NIGHT. VORT LOBE EXTENDING SOUTH OFF THE MAIN FEATURE AND SOME MID
LEVEL FORCING...WILL COMBINE WITH LOW-MID LVL WAA FOR SOME MID-HIGH
CLOUD FORMATION MONDAY EVENING...BUT LITTLE ELSE.

BEFORE THEN...SFC RIDGE CENTER NOW DRAPED FROM THE EASTERN
U.P. OF MI TO NORTH CENTRAL KS...WILL SLIDE EAST OVER THE CWA
TONIGHT FOR CLR SKIES AND CALMING NORTHEAST WINDS. LITTLE AIRMASS
EXCHANGE...MAYBE FROM EAST CENTRAL WI WHICH HIT 0 TO 3 BELOW LAST
NIGHT...AND ABOVE MENTIONED CONDITIONS SETTING UP OVER FRESH SNOW
COVER SHOULD MAKE FOR COLD NIGHT. WILL TAKE PREVIOUS SHIFTS LEAD IN
UNDERCUTTING TEMP GUIDANCE BY ALMOST 10 DEGREES FOR MON LOWS...
LOOKING AT WHAT OCCURRED LAST NIGHT AND TAKING INTO ACCOUNT UPSTREAM
AIR INFLUX. MOST OF CWA TO RANGE FROM ZERO TO 5 ABOVE. RIDGE TO
LINGER TOO LONG INTO MONDAY FOR BETTER MIXING POTENTIAL OF
WARMING RETURN FLOW ALOFT(WHICH STARTS KINDA LATE IN THE DAY
ANYWAY)...AND WILL SIDE WITH COOLER MAV HIGHS...ESPECIALLY AFTER COLD
START AND WITH LINGERING SNOW COVER.

SOUTH BREEZE INDUCED AND MAINTAINED OVER THE AREA AHEAD OF NORTHERN
STREAM SYSTEM ...ALONG WITH SOME MID TO HIGH CLOUDS WILL PREVENT TEMP
BOTTOM OUT MONDAY NIGHT...AND FWC AND MAV IN GOOD AGREEMENT AND LOOK
REASONABLE. SOME PATCHY FOG POSSIBLE...BUT WILL NOT MENTION AT THIS
TIME.

TUESDAY THE WILD CARD IN THE TEMP GAME...WITH FWC ADVERTISING UPPER
30S NORTH...AND MID TO UPPER 40S CENTRAL AND SOUTH. THE MAV IS
ALMOST 10 DEGREES COLDER IN CORRESPONDING AREAS OF THE CWA. THERMAL
AND WIND PROFILES SUGGEST BETTER MIXING POTENTIAL THAN PREVIOUS
DAY...AND MAY TIP TIDE TOWARD WARMER NUMBERS. BUT WILL TAKE
COMPROMISE FOR NOW. CLOUDS INCREASE AHEAD OF SOUTHERN STREAM SYSTEM
TUE NIGHT.

.LONGER RANGE(WED-SUN)...MEDIUM RANGE MODELS CHANGING FROM PREVIOUS
RUNS...BUT STILL GENERALLY AGREE ON MIDWEEK SPLIT FLOW PATTERN...
WITH EVOLVEMENT TOWARD SOME PHASING OF NORTHERN AND SOUTHERN
STREAMS TOWARD NEXT WEEKEND. ECMWF AND UKMET NOW SIDE WITH X-GFS AND
MRF OF KEEPING SOUTHERN STREAM SYSTEM AND ITS PRECIP SOUTH OF THE
CWA ON WED. X-ETA ODD MODEL OUT WITH MUCH FURTHER NORTH TRACK OF SFC
WAVE AND ACCUMULATING SNOW INTO THE SOUTHERN CWA BY WED...WILL BANK
ON BAROCLINIC TRACK SETTING UP FARTHER SOUTH TO SUPPORT THE OTHER
MODEL TRENDS. FAR SOUTHERN CWA MAY BE NOT OUT OF WOODS THOUGH FOR
POSSIBLE PRECIP TUE NIGHT INTO WED...STAY TUNED! SFC HIGH TO THEN
TEMPORARILY DROP ACRS THE AREA BRINGING BRIEF COOL DOWN FOR LATER WED
AND WED NIGHT...BEFORE RETURN FLOW SETS UP ON THU AS THIS RIDGE
PASSES TO THE EAST. EURO SLOWEST WITH HIGH PASSAGE AND LINGERS
FEATURE ENOUGH WITH LESS OF RETURN FLOW FOR HIGH TEMPS SIMILAR TO
WED(MID 30S TO LOW 40S)...WHILE MRF SUPPORTS MID TO UPPER 40S OVER
MUCH OF THE CWA. WILL TREND TOWARD EURO. QUITE A FEW DIFFERENCES WITH
PHASING ISSUES NOW FROM PREVIOUS RUNS IN HANDLING END OF WEEK STORM
SYSTEM. VARIOUS MODELS AND GENERAL ENSEMBLE NOW KEEP MAIN SFC LOW
MUCH FURTHER SOUTH AND REV IT UP THE EAST COAST ON SAT. STILL A LONG
WAY OUT AND PLENTY OF TIME FOR MODELS TO CHANGE THEIR TUNE AGAIN WITH
HANDLING AND PHASING ISSUES IN UP-COMING RUNS. CONTINUED WAA IN
AMPLIFYING FLOW AHEAD OF SYSTEM MAY MEAN MORE OF A RAIN THREAT OVER
MOST OF THE CWA ON FRI...THEN SWITCHING TO SNOW FRI NIGHT AND INTO
SAT. ALL MODELS SUGGEST A LARGE COLD YUKON HIGH PERCHED ACRS WESTERN
CANADA...TO COME SPILLING DOWN ACRS THE UPPER MIDWEST BEHIND
DEPARTING SYSTEM LATER ON SAT. THIS COULD MEAN FRIGID 2ND HALF TO
WEEKEND WITH OCCASIONAL LIGHT SNOW AS POLAR VORTEX SETS UP OVER THE
GRT LKS. TEMP GUIDANCE FOR SUNDAY LOWS AND HIGHS MAY HAVE TO BE
SERIOUSLY UNDERCUT.


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

$$

12