[LeArc] Forecast Discussion : MLI@ 8/7/2003 4:35:47 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 070933
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
420 AM CDT THU AUG 7 2003

SHORT RANGE MODELS AGAIN IN GENERALLY AGREEMENT IN KEEPING
MERIDIONAL FLOW PLUNGING DOWN ACRS THE AREA THROUGH THE NEAR TERM AS
EAST COAST L/W TROUGH MAINTAINS. THUS EXPECT SIMILAR DAYS ON TAP
TODAY AND FRIDAY AS YESTERDAY...WITH INCREASING NORTHEAST SFC FETCH
ON FRI OFF LK MI POSSIBLY HAVING SOME TEMPERING EFFECT ON HIGH
TEMPS TOMORROW...ESPECIALLY ACRS THE NORTHEAST CWA.

MODELS IN THEIR VARYING WAYS RIPPLE WEAK PULSES OF ENERGY DOWN
THROUGH STEEP NORTHERLY FLOW...BUT INDUCED POS OMEGAS BY THESE VORTS
ALMOST NIL. STILL...FCST SOUNDINGS AND LLVL LAPSE RATES SUGGEST
ANOTHER UNSTABLE AFTERNOON ON TAP WITH EXPECTED TOWERING CU
POPPING OVER MOST OF THE CWA. FCST CONVECTIVE TEMPS OF LOWER 80S
SHOULD AGAIN BE BREACHED. EASTERN HALF TO THIRD OF THE CWA(UNDER AND
JUST TO THE LEE OF VORT PROPAGATION PATH) MAY AGAIN BE SUSCEPTIBLE TO
MID TO LATE AFTERNOON WIDELY SCATTERED SHOWERS AND HAVE KEPT 20-30
POPS TO ACCOUNT FOR CONVECTION...BUT EXPECT LESS ACTIVITY THAN
YESTERDAY. MORE INSOLATION AND MIXING THAN EXPECTED YESTERDAY ALLOWED
TEMPS TO GET PUMPED UP WELL ABOVE GUIDANCE ON WED...AND FCST THERMAL
PARAMETERS REMAIN SIMILAR TODAY. THUS WILL PLAY PERSISTENCE CARD...
WHICH WILL MEAN GOING WITH HIGHS ABOVE GUIDANCE(GENERALLY MID 80S).

EXPECT CLEARING TONIGHT UNDER SFC RIDGE AXIS...WITH TEMPS COOLING
CLOSE TO DPTS LATE(LOW TO MID 60S). HAVE KEPT ONGOING PATCHY FOG
WORDING FOR NOW TO AVOID FLIP-FLOPPING...BUT LIGHT NORTHERLY BREEZE
MAY BE ENOUGH TO KEEP ANY FOG DEVELOPMENT TO THE EXTENT OF BEING NOT
WORTHY OF ZONE MENTION. AS FOR FRIDAY...UPPER RIDGE MAY EDGE FAR
ENOUGH EAST TO ALLOW FOR DRY AND MOSTLY SUNNY DAY...ALTHOUGH
LLVL UNSTABLENESS STILL PROGGED TO OCCUR. SFC RIDGE AXIS SHIFTS EAST-
SOUTHEAST ACRS LK SUPERIOR AND THE U.P. OF MI FRIDAY...WITH
RESULTANT SOUTHERLY GRADIENT SQUEEZING MORE OF A NORTHEAST FLOW OFF
LK MI. THIS MAY KEEP HIGH TEMPS MORE IN THE RANGE OF LOWER 80S FOR
FRI AFTERNOON...ESPECIALLY IN THE NORTHEAST CWA. EARLY AUGUST
INSOLATION AND EXTENT OF NORTHEAST FLOW MIXING WILL STILL ALLOW
SOUTHWEST HALF OF THE CWA TO STRIVE TOWARD THE MID 80S(STILL ABOVE
GUIDANCE). CLEAR AND SOMEWHAT COOLER NIGHT EXPECTED FRI NIGHT AS
NORTHEAST FETCH STARTS TO HAVE EFFECT ON THE AREA...BUT NORTHWEST-
TO-SOUTHEAST H7-H3 MB THICKNESS PATTERNS MAY ADVECT CI DEBRIS FROM
MCS SPAWNING GROUNDS IN THE DAKOTAS...DOWN OVER THE LOCAL AREA.
..12..

SATURDAY NIGHT THROUGH MONDAY...
UPPER LEVEL RIDGE REMAINS WEST OF THE REGION...WITH SMALL BUT QUITE
POTENT SHORTWAVES MOVING THROUGH THE UPPER LEVEL FLOW...OVER THE TOP
OF THE RIDGE.  OF CONCERN IS A WEAKER WAVE ALOFT....BUT MANIFESTS AS
A BACKDOOR FRONT THAT DROPS SOUTH ACROSS THE AREA SUNDAY NIGHT.
TIMING IS UNFAVORABLE...AND THERE ISN'T VERY MUCH MOISTURE
ASSOCIATED WITH THIS WAVE...SO HAVE DECIDED TO LEAVE DRY.

TUESDAY AND WEDNESDAY...TUESDAY AND TUESDAY NIGHT A FAIRLY POTENT
VORT MAX MOVES ACROSS THE AREA AGAIN...BUT THIS TIME THE SYNOPTIC
FEATURES AND EVEN TIMING WOULD FAVOR AN MCS LIKE FEATURE.  A SURFACE
LOW PRESSURE SYSTEM DEVELOPING OVER WESTERN ND WILL CAUSE SOUTHERLY
FLOW TO DEVELOP OVER THE CWA...AND THE WAVE WOULD MOVE OVER THESE
FEATURES.  SO...TUESDAY AFTERNOON AND EVENING SHOULD HAVE SOME
SHOWERS AND THUNDERSTORMS.  BY WEDNESDAY THE SURFACE LOW SHIFTS A
LITTLE FARTHER NORTH...AND A SURFACE WARM FRONT SEEMS TO FORM OVER
SOUTHERN MN AND CENTRAL WI.  700MB TEMPS WOULD IMPLY CAPPING...SO
HAVE KEPT PRECIP OUT OF THIS PERIOD.   ..LE..


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

$$

12/LE