446 
FXUS64 KLCH 121838
AFDLCH

SOUTHWEST LOUISIANA AND SOUTHEAST TEXAS FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
138 PM CDT FRI OCT 12 2001

.TONIGHT...
GULF AIR ADVECTION STRENGTHENS. EXPECT INCREASING CLOUDINESS AS GULF
AIR OVERRIDES FILM OF DRIER AIR AT THE SURFACE. THE ATMOSPHERE IS
BEING PRE-CONDITIONED FOR UPCOMING HEAVY RAIN EVENT. INCOMING GULF
AIR SHOULD KEEP MINIMUMS ON THE WARM SIDE (ABOUT 10 TO 15 F DEGREES
ABOVE NORMAL).

.SATURDAY...
A HEAVY RAIN EVENT SEEMS LIKELY. STRONG ADIABATIC LIFT WILL BE IN
PLACE. THE NGM TRAJECTORY MODEL COMPUTES A NET VERTICAL DISPLACEMENT
OF THE 700 MB SURFACE AT +80 MB WITHIN A 12 HOUR PERIOD). OTHER
FACTORS NOTED ACROSS THE FORECAST AREA INCLUDE...700-300 MB THICKNESS
DIFLUENCE...700-300 MB QUASI-GEOSTROPHIC LIFT...AND 1000-500 MB MEAN
RH NEAR 90 PERCENT.

MARGINAL INSTABILITY SEEMS TO BE THE ONLY LIMITING FACTOR. THE 700-
300 MB LAPSE RATES ARE RUNNING NEAR 6.5 C DEG PER KM...WHICH IS
MARGINALLY UNSTABLE (FOR A CLOUDY AIR PARCEL UNDERGOING AVERAGE
ENTRAINMENT IN A MOIST ENVIRONMENT).

AFTER TALKING WITH THE SURROUNDING OFFICES...I HAVE DECIDED TO ISSUE
A FLASH FLOOD WATCH FOR SOUTHEAST TEXAS...AND FOR WEST CENTRAL AND
SOUTHWEST LOUISIANA. ALSO I WILL ISSUE A SPECIAL WEATHER STATEMENT
(HEAVY RAIN OUTLOOK) TO COVER THE REMAINDER (EAST CENTRAL AND SOUTH
CENTRAL LOUISIANA).

SPECIAL THANKS TO HOUSTON, NEW ORLEANS, SHREVEPORT OFFICES AND TO
THE HYDRO-METEOROLOGICAL PREDICTION CENTER.

.LCH...FFA (FLOOD WATCH) TXZ180>182-201-215-216
    ...                  LAZ027-030-031-041-042-051

.PRELIMINARY NUMBERS...
AEX 70/78/55/76/49/73/50 7830000
BPT 73/80/56/77/55/75/58 4800000
LCH 72/80/56/77/53/75/57 4800000
LFT 70/83/58/76/52/73/54 4830000
$$
TRARES