[LeArc] Forecast Discussion : MLI@ 7/1/2003 3:13:40 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 012005
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CDT TUE JUL 1 2003

.OVERVIEW...MINOR CHANGES TO PAST COUPLE OF DAYS...MOST NOTICEABLE IS
A SLIVER OF 65-70 DEWPOINTS ALONG AND SOUTH OF HIGHWAY 34 ALONG OLD
FRONTAL BOUNDARY. THIS HAS SPAWNED IN THE PAST HOUR A BAND OF PULSE
THUNDERSTORMS AND SHOWERS THAT EXTENDS ACROSS NORTH CENTRAL MISSOURI
TO NEAR QUINCY. MOVEMENT IS ESE AT 5 MPH.  ALL INDICATIONS ARE WITH
NO COHERENT FORCING AND WEAK SHEAR...THESE WILL DISSIPATE WITHIN AN
HOUR AFTER SUNSET.  STILL NEARLY STATIONERY PATTERN WITH AIRMASS
SLOWLY MODIFYING TO MORE TROPICAL CHARACTERISTICS.  TEMPS & DEWPOINTS
ARE BOTH 2-5 DEGREES ON AVERAGE HIGHER AT 19Z THEN A DAY BEFORE.

...WARMUP NEXT FEW DAYS NEAR TERM CHALLENGE WITH CONVECTION LATE
THURSDAY INTO EARLY NEXT WEEK MEDIUM RANGE ISSUE...

.DIAGNOSIS (DAYS 1-3)...CONVECTION IN FAR SW OF FORECAST AREA WILL
NEED TO HANDLE WITH NOWCAST TOOLS...THEY ALL SUGGEST THIS TO SLOWLY
DIE BETWEEN 7 AND 9 PM AS WE LOSE HEATING.  AGAIN RAISE MIN TEMPS A
COUPLE DEGREES FROM YESTERDAY BASED ON PERSISTENCE WHICH WOULD BE A
CATEGORY BELOW NORTH 1/2 AND NEAR GUIDANCE SOUTH.  HIGHER DEWPOINTS
SOUTH OF HIGHWAY 34 WILL GO WITH PATCHY FOG TOWARD MORNING BASED ON
THIS MORNING'S FOG THERE.  THEN WARMER AND MORE HUMID WITH HIGH TEMPS
ON HIGH SIDE OF BLEND WED/THU.  MODELS CONTINUE TO SUGGEST FAVORABLE
CONVECTION COMPLEX INITIATION IN NW IA OR SW SD TOWARD SUNSET
THURSDAY MOVING INTO NW 1/2 OF AREA LATE...NORMAL MODEL QPF
PROBLEMS...ESPECIALLY ETA.  PARAMETERS OF SHEAR...INSTABILITY AND SFC
MOISTURE AND FORCING WITH SLOW MOVING FRONT ALL SUPPORT ORGANIZED
SYSTEMS. APPEARS ASYMMETRICAL SQUALL LINE PREFERRED MODE.  THEN
CONVECTIVE DEBRIS DURING DAY FRIDAY AND STRONGER FOCUS AND MID LEVEL
WINDS SUGGEST VIGOROUS CONVECTION FRIDAY PM AND EVENING WITH
POTENTIALLY DAMAGING WINDS  UP TO 70 MPH AND LARGE HAIL CAUSED BY
BOWING SEGMENTS.  MINOR CHANGES TO EXISTING POPS...GOING HIGH SIDE OF
GUIDANCE CONSTRAINED BY BLENDING WITH NDFD DATABASE OF NEARBY
OFFICES. REASONABLE LIKELY WORDING NEEDED NEXT 24-36 HOURS. LOCALLY
HEAVY RAINS ALSO A GIVEN WITH PRECIPITABLE WATER 1.5" TO 2.0" AS WELL
SEVERE WX.

.EXTENDED (SAT-TUE)...MODERATE ZONAL FLOW CONTINUES WITH EMBEDDED
DISTURBANCES ALOFT AND SURFACE BOUNDARIES REMAINING NEARBY SUGGESTED
BY ALL MEDIUM RANGE MODELS KEEPING AN ACTIVE PERIOD.  CONDITIONS
REMAIN FAVORABLE FOR ORGANIZED CONVECTIVE EVENTS WITH MID LEVEL WINDS
OF 30-50 KNOTS.  BEST POTENTIAL FOR MOST INTENSE CONVECTION
LATE SUNDAY INTO TUESDAY.   VERY WARM LOW LEVEL THERMAL FIELDS IN
THIS ENVIRONMENT...ALONG WITH DEWPOINTS NEAR 70 (HIGH INSTABILITY AND
MOISTURE) BOUNDARIES AND FOCUSED FORCING...SUGGEST ORGANIZED
INTENSE CONVECTION WITH BOWING SEGMENTS AND POSSIBLY DERECHOES...OR
LARGER SCALE HIGH WIND SYSTEMS. PRELIMINARY CALCULATIONS CONTINUE TO
SUGGEST MAX WIND POTENTIAL OF 70 MPH OR MORE WITH SOME HAIL...WILL
UPDATE HWODVN FOR THIS RISK AND KEEP CHANCE SHOWERS STORMS THROUGH
TUESDAY AND HEAVY RAIN POTENTIAL.  MOST AREAS SHOULD SEE SIGNIFICANT
RAINS WITH LOCALLY HEAVY AMOUNTS BY TUESDAY WITH FLOODING POTENTIAL.

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

$$

NICHOLS