FNUS73 KLSX 191535
FWSLSX

SPOT FORECAST FOR BRM...ST. CHARLES COUNTY PARKS AND RECREATION
NATIONAL WEATHER SERVICE ST LOUIS MO
935 AM CST THU FEB 19 2009

FORECAST IS BASED ON PRESCRIBED BURN FOR FEBRUARY 20.
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE
NATIONAL WEATHER SERVICE.

.DISCUSSION...
A RIDGE OF HIGH PRESSURE WILL MOVE ACROSS THE PRESCRIBED BURN
AREA TONIGHT. A LIGHT WIND AND CLEAR SKY WILL ALLOW THE
TEMPERATURE TO FALL BACK INTO THE TEENS AND RELATIVE HUMIDITY
VALUES TO RISE TO NEAR 80 PERCENT BY DAYBREAK.

A FAST MOVING LOW PRESSURE SYSTEM IS PROGGED TO DIVE SOUTHEAST
TOWARD THE FORECAST AREA TOMORROW AFTERNOON. THIS WILL CAUSE
THE WIND TO QUICKLY TURN AROUND TO THE SOUTHWEST TOMORROW
MORNING AND INCREASE INTO THE AFTERNOON AS THE PRESSURE
GRADIENT TIGHTENS ACROSS THE AREA.

MORNING BURN CONDITIONS DO NOT LOOK VERY FAVORABLE AS
INVERSION WILL BE SLOW TO LIFT...MIXING HEIGHTS AROUND
1200 FEET AT 9 AM...AND A LIGHT TRANSPORT WIND.

AFTERNOON LOOKS MORE FAVORABLE AS MIXING HEIGHT SHOULD RISE
ABOVE 3000 FEET AND BETTER TRANSPORT WIND IS REALIZED WITH
TIGHTER PRESSURE GRADIENT. RELATIVE HUMIDITY SHOULD DROP
BELOW 40 PERCENT...WITH A MINIMUM VALUE OF 30 PERCENT
EXPECTED. VENTILATION INDEX WILL NOT BE AS FAVORABLE AS
TODAY...BUT GIVEN THE TYPE OF FUEL YOU ARE BURNING...A QUICK
DISPERSION OF THE SMOKE SHOULD OCCUR IF THE PRESCRIBED BURN
IS CONDUCTED IN THE AFTERNOON.

.FRIDAY...

SKY/WEATHER.........PARTLY CLOUDY.
CWR.................0 PERCENT.
LAL.................NO TSTMS.
TEMPERATURE.........MAX 46.
RH..................MIN 30 PERCENT.
WIND...EYE LEVEL....SOUTHWEST WIND 7 MPH INCREASING TO 10 MPH IN
                    THE AFTERNOON. AFTERNOON GUSTS TO 15 MPH.
WIND...20 FT........SOUTHWEST WIND 9 MPH INCREASING TO 12 MPH IN
                    THE AFTERNOON. AFTERNOON GUSTS TO 15 MPH.
HAINES INDEX........3 OR VERY LOW POTENTIAL FOR LARGE PLUME
                    DOMINATED FIRE GROWTH.
MIXING HEIGHT.......3100 FT AGL IN THE AFTERNOON.
TRANSPORT WIND......SOUTHWEST AROUND 15 MPH IN THE AFTERNOON.
VENTILATION RATE....FAIR (6300 M 2/S).

$$

FORECASTER...CVKING
REQUESTED BY...FORESTRY SUPERVISOR
TYPE OF REQUEST...PRESCRIBED
.TAG 20090219.BRM__.01/LSX