Area Forecast Discussion
Issued by NWS Lake Charles, LA

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FXUS64 KLCH 301733
AFDLCH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1233 PM CDT THU JUL 30 2015

.DISCUSSION...
FOR THE 30/18Z TAF ISSUANCE.

&&

.AVIATION...
A FRONTAL BOUNDARY LIES ACROSS NORTHERN LOUISIANA AND IS EXPECTED
TO MOVE SOUTHWARD INTO THE FORECAST AREA LATER THIS EVENING AND
TONIGHT. STILL PLENTY OF SUBSIDENCE AHEAD OF THE FRONT...ALONG
WITH NORTHERLY WINDS...THEREFORE KEEPING BOTH CONVECTION AND SEA
BREEZE IN CHECK. DO EXPECT SOME CONVECTION TO DEVELOP DURING THE
AFTERNOON AS SURFACE TEMPERATURES APPROACH THE CENTURY
MARK...ALLOWING A FEW STORMS TO POP...AND ALSO A LATE IN THE DAY
SEABREEZE WILL TRY TO MOVE INLAND CLOSE TO 31/00Z. THUS...HAVE
PLACED VCTS AT ALL SITES TO ACCOUNT FOR THIS...WITH ANY ACTIVITY
THAT DOES DEVELOP STARTING TO WIND DOWN BY 31/04Z. AWAY FROM ANY
CONVECTION...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD.

RUA

&&

.PREV DISCUSSION... /ISSUED 1032 AM CDT THU JUL 30 2015/

DISCUSSION...
WX MAP SHOWS FLATTENING RIDGE ALOFT...CENTERED OVER TX THIS
MORNING. FOR OUR REGION...NE FLOW ALONG WITH SUFFICIENT SUBSIDENCEWILL
CONTINUE TO PROVIDE THE HOTTEST DAY OF THE SUMMER SO FAR. MANY
AREAS STARTED OFF IN THE UPPER 70S TO LOWER 80S FOR LOWS THIS
MORNING (81 AT LCH AIRPORT). AT 10 AM...TEMPS ALREADY IN THE LOWER
90S AT MANY LOCATIONS WITH HEAT INDEX VALUES ALREADY 100-105. WITH
THIS...BUMPED UP AFTERNOON HIGHS A COUPLE OF DEGREES...NOW
EXPECTING 100-101 ALONG AND N OF I-10...WITH A RANGE OF MID/UPPER
90S FOR THE COASTAL PARISHES/COUNTIES...AND LOWER 90S ALONG THE
IMMEDIATE COAST. HEAT INDEX VALUES COMPUTED TO REACH 109-113...AND
POSSIBLY HIGHER FOR AN HOUR DURING PEAK HEATING. THUS...THE
AREAWIDE HEAT ADVISORY CONTINUES AND IS VALID THRU 7 PM.

THE OTHER ISSUE WILL BE CONVECTIVE TSRA DEVELOPMENT LATER THIS
AFTERNOON AND EVENING DURING AND AFTER MAX HEATING. SPC CONTINUES
REGION IN MARGINAL RISK...MAINLY FOR DAMAGING WINDS FROM DOWNBURST
POTENTIAL. CURRENT FORECAST HAS 30-40% WITH THE EMPHASIS OVER SC
LA AND THE COASTAL WATERS LATER THIS EVENING.

DML

PREV DISCUSSION... /ISSUED 626 AM CDT THU JUL 30 2015/

AVIATION...THUNDERSTORMS HAVE DEVELOPED OVER VERMILION PARISH
THIS MORNING AND ADDITIONAL STORMS ARE EXPECTED TODAY, BUT MAINLY
DURING THE AFTERNOON AND EARLY EVENING. EVEN WITH THE SCATTERED
STORMS EXPECTED TODAY, MOSTLY VFR CONDITIONS ARE EXPECTED THROUGH
THE PERIOD. LOWER VIS AND CEILINGS CAN BE EXPECTED AROUND STORMS.
WINDS WILL BE LIGHT AND VARY FROM NW TO NE FOR MOST OF THE PERIOD,
HOWEVER THE SEA BREEZE WILL PUSH TO NEAR 1-10 DURING MID TO LATE
AFTERNOON AND WINDS MAY BE VRB NEAR STORMS.

PREV DISCUSSION... /ISSUED 535 AM CDT THU JUL 30 2015/

DISCUSSION...
LATEST UPPER AIR ANALYSIS/WATER VAPOR SATELLITE IMAGERY SHOWED A
DEEP LAYER RIDGE CENTERED NEAR THE ARKLATEX...THOUGH MODEL
GUIDANCE CONTINUES TO DEPICT THIS FEATURE RETROGRADING WWD AS A
TROF DIGS INTO THE ERN CONUS. THIS IS PROGGED TO OPEN THE DOOR FOR
A FRONTAL BOUNDARY TO SAG INTO THE AREA LATE TONIGHT INTO
TOMORROW.

MSTR INFLUX/POOLING AHEAD OF THE BOUNDARY WILL AID IN KEEPING
AFTERNOON RH VALUES A LITTLE HIGHER THAN YESTERDAY...WHILE
TEMPERATURES SOAR ONCE AGAIN INTO THE UPPER 90S TO NEAR 100
DEGREES. THIS YIELDS APPARENT TEMPERATURE VALUES AT OR ABOVE THE
109 DEGREE HEAT ADVISORY CRITERIA FOR A SIGNIFICANT PART OF THE
AREA THIS AFTERNOON. THIS FCST IS NOT WITHOUT
UNCERTAINTY...HOWEVER...AS THE POTENTIAL FOR INCREASED
CLOUDS/CONVECTION MODERATING TEMPERATURES OR LOWER DEWPOINTS THAN
FCST COULD ALL PLAY FOILS. CURRENT THINKING IS THAT CONVECTION
WILL TEND TO BE ISOLATED/SCATTERED IN NATURE...AND FOR THE MOST
PART HOLD OFF UNTIL PEAK TEMPERATURES HAVE ALREADY BEEN REACHED.

ANOTHER WARM AND MUGGY NIGHT IS IN STORE...THOUGH DRIER AIR IS
PROGGED TO START FILTERING INTO CENTRAL LOUISIANA WITH THE PASSAGE
OF THE FRONT DURING THE OVERNIGHT HRS. THOUGH THERE IS STILL SOME
DISPARITY/SPREAD IN GUIDANCE...MODEL PROGS ARE GENERALLY POINTING
TWD QUITE A DRY AIR INTRUSION BEHIND THE FRONT. WHILE DEWPOINT VALUES
WERE LOWERED A FAIR AMT FROM THE PREVIOUS FCST...FURTHER
REDUCTIONS MAY BE WARRANTED IN SUBSEQUENT ISSUANCES.

ONLY A FEW DEGREES GETS INITIALLY SHAVED OFF OF TEMPERATURES IN
THE WAKE OF THE FRONT...BUT THE DRIER AIR WILL AT LEAST HELP HOLD
DOWN AFTERNOON APPARENT TEMPERATURES. RAIN CHANCES ARE ALSO
SHUNTED SOUTH WITH THE BETTER MSTR...THOUGH AT LEAST SMALL CHANCES
LINGER ALONG THE COAST AND OVER THE COASTAL WATERS THROUGH THE
WEEKEND WITH THE BOUNDARY STALLING NEAR THE COAST.

UPPER RIDGE PROGGED TO RE-BUILD A BIT EASTWARD FOR THE EARLY TO
MIDDLE PART OF NEXT WEEK...BUT IS ERODED ONCE AGAIN BY ADDITIONAL
SHORTWAVE ENERGY TRAVERSING THE CENTRAL CONUS.

13

MARINE...
A PREVALENT WEST TO NORTHWEST FLOW IS EXPECTED TODAY AS A WEAK
FRONTAL BOUNDARY SAGS INTO THE REGION. THIS FRONT...COUPLED WITH
INCREASING MOISTURE FROM THE EASTERN GULF...WILL SIGNIFICANTLY
INCREASE THE CHANCES OF SHOWERS AND THUNDERSTORMS TONIGHT INTO
FRIDAY. THE FRONT IS EXPECTED TO STALL NEAR THE COAST...KEEPING
ELEVATED CHANCES OF SHOWERS AND THUNDERSTORMS INTO THE WEEKEND.

13

&&

.PRELIMINARY POINT TEMPS/POPS...
AEX 101  75  96  72 /  30  20  20  10
LCH 100  78  96  75 /  40  30  20  10
LFT 100  78  96  73 /  40  30  20  10
BPT 100  78  96  76 /  30  20  20  10

&&

.LCH WATCHES/WARNINGS/ADVISORIES...
LA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR LAZ027>033-041>045-
     052>055-073-074.

TX...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR TXZ180-201-215-216-
     259>262.

GM...NONE.
&&

$$


AVIATION...07



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