Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 251746
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1246 PM CDT MON AUG 25 2014

.DISCUSSION...
SEE AVIATION FOR 18Z TAF DISCUSSION.

&&

.AVIATION...
WINDS REMAIN SOMEWHAT VARIABLE AS SURFACE HIGH PRESSURE LINGERS
ACROSS THE REGION. HAVE REMOVED MENTION OF SHRA THIS AFTERNOON AS
COVERAGE LOOKS TO BE LOW. BETTER RAIN CHANCES ARRIVE OVERNIGHT AS
A DISTURBANCE APPROACHES FROM THE EAST. EXPECT EAST WINDS WITH
SCATTERED SHOWERS AND THUNDERSTORMS DURING THE DAY ON TUESDAY.

38/MV

&&

.PREV DISCUSSION... /ISSUED 1001 AM CDT MON AUG 25 2014/

DISCUSSION...
VERY MINOR CHANGES TO THE FORECAST PLANNED THIS MORNING...MAINLY
GRID CHANGES. TEMPERATURES A DEGREE OR TWO LOWER THIS MORNING AND
SOME HIGH CLOUDS MOVING OVER THE AREA. LAND BREEZE PUSHING OUT
OVER THE GULF. MOISTURE POOLING OVER THE GULF S OF LCH WILL START
TO SHIFT WEST TODAY AND MAY SEE SOME ISOLATED TO WIDELY SCATTERED
SHOWERS AND THUNDERSTORMS MAINLY AROUND GALVESTON BAY AND
EASTWARD LATE THIS AFTERNOON. STORMS MAY DEVELOP WEST AFTER 6 PM
ALONG THE SEABREEZE BUT SHOULD BE ISOLATED IN NATURE ACROSS THE
HOUSTON AREA. RAIN CHANCES STILL LOOK GOOD TOMORROW MORNING AND
AFTERNOON. 12Z NAM STILL LOWERING PRESSURES IN THE NW GULF AND
TRACKING A WEAK LOW TOWARD CRP WED NIGHT.

ON THE MARINE SIDE WILL PROBABLY NUDGE UP THE SEAS A FOOT OR TWO
FOR MID WEEK BUT WILL WAIT TO SEE THE GFS/ECMWF.
45

PREV DISCUSSION... /ISSUED 631 AM CDT MON AUG 25 2014/

DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.

40

AVIATION...
WITH HIGH PRESSURE OVERHEAD...EXPECT VFR FOR THE MOST PART THROUGH
THE MORNING. THE EXCEPTION WILL BE AT KLBX AND KSGR WHERE PATCHY
GROUND FOG SHOULD LIFT BY AROUND 13Z.

FOR THIS AFTERNOON...THE HIGH RESOLUTION MODELS ARE STARING
ISOLATED SHOWERS BETWEEN 18Z AND 21Z. THE NAM BUFR FORECAST
SOUNDINGS SUPPORT THIS AND WILL STAY WITH VCSH FOR NOW GIVEN THE
LOW PROBABILITY. THE UPPER LEVEL LOW PRESSURE TROUGH OVER CENTRAL
GULF WILL MOVE TOWARD AND OVER SE TX TONIGHT AND TUESDAY MORNING.
THE MODELS START RAIN CHANCES OVER KIAH AND KHOU AROUND 06Z.

40

PREV DISCUSSION... /ISSUED 414 AM CDT MON AUG 25 2014/

DISCUSSION...
AT 08Z...SURFACE HIGH PRESSURE EXTENDED FROM ARKANSAS TO THE
WESTERN GULF AND A WEAK TROUGH OF LOW PRESSURE EXTENDED FROM
EASTERN CO INTO EASTERN NM. AT 850 MB...A WEAK HIGH WAS OVER EAST
TEXAS WITH DEEPER MOISTURE CONFINED TO AREAS NORTHEAST OF A
SHREVEPORT TO NEW ORLEANS LINE. 850 TEMPS LOOK A DEGREE OR TWO
WARMER THAN YESTERDAY. AT 700 MB...HIGH PRESSURE HAD RETREATED A
BIT AND IS NOW OVER SE MISSOURI. MOISTURE REMAINS SCARCE AT THIS
LEVEL. AT 250 MB...A STRONG UPPER LEVEL HIGH WAS LOCATED OVER
WESTERN NC AND THIS FEATURE EXTENDS SW INTO EASTERN TEXAS. A WEAK
S/WV WAS NOTED OVER EASTERN NM.

PATCHY GROUND FOG WILL AGAIN DEVELOP AROUND SUNRISE IN MANY OF THE
RURAL LOCATIONS BUT THE FOG IS SHALLOW AND WILL BURN OFF QUICKLY
LATER THIS MORNING. GUIDANCE HAS BEEN TOO WARM FOR KCLL THE LAST
FEW DAYS BUT WITH SUBTLE WARMING AT 850-700...FEEL 100 DEGREES IS
WARRANTED FOR THE NW ZONES TODAY. HEAT INDEX VALUES ALONG THE
COAST FAILED TO REACH 105 DEGREES YESTERDAY SO NO NEED TO ISSUE A
HEAT ADVISORY. OVERALL...JUST ANOTHER HOT DAY IN AUGUST.

AN INVERTED 500 MB TROUGH WAS LOCATED OVER EXTREME EASTERN
LOUISIANA AND THIS FEATURE SHOWS UP WELL IN WATER VAPOR IMAGERY.
THE TROUGH WILL APPROACH SE TX TONIGHT AND MOVE ACROSS THE REGION
EARLY TUESDAY. BENIGN MOISTURE LEVELS THIS MORNING WILL RAPIDLY
INCREASE DURING THE DAY AND PW VALUES WILL RISE FROM 1.5 INCHES
THIS MORNING TO 2.15 INCHES BY TUES MORNING. MOISTURE LEVELS
SHOULD BE SUFFICIENT BY LATE THIS AFTERNOON TO FOSTER A FEW
SHRA/TSRA OVER MAINLY THE EXTREME EASTERN ZONES AND ALONG THE
COAST. MOISTURE LEVELS AND INSTABILITY SEEM TO PEAK TUESDAY
MORNING SO WILL CARRY HIGHEST RAIN CHANCES FOR TUESDAY MORNING
WITH SOME DRYING FOR LATER IN THE DAY. WHAT IS TROUBLING IS THE
POSITION OF THE VORT LOBE WHICH BASICALLY STAYS JUST OFF THE COAST
AND NEVER MOVES INLAND. IT IS POSSIBLE THAT MUCH OF THE RAIN COULD
FOCUS JUST OFF THE COAST (AS ADVERTISED BY THE 4 KM WRF AND HI-RES
ARW). THE ECMWF HAS INITIALIZED BEST AND HAS BEEN THE MOST
CONSISTENT SO HAVE LEANED HEAVILY TOWARD THE WETTER ECMWF SOLN.
PW VALUES DRY OUT SIGNIFICANTLY ON WED AND FALL TO BETWEEN 1.3-1.5
INCHES AND FCST SOUNDINGS SHOW TREMENDOUS DRYING AT 700 MB.
TRIMMED POPS BACK A BIT ON WED DUE TO LOWER MOISTURE LEVELS BUT
CONVECTIVE TEMPS OF AROUND 90 DEGREES ARE MORE THAN REACHABLE SO
STILL EXPECTING ISOLATED TO SCATTERED SHRA/TSRA.

A VIGOROUS UPPER TROUGH OVER THE INTERMOUNTAIN WEST WILL SLOWLY
APPROACH THE SOUTH CENTRAL PLAINS ON THU-FRI. ASCENT ON THE
EASTERN SIDE OF THIS FEATURE SHOULD INCREASE AND COUPLED WITH DEEP
MOISTURE AND DAYTIME HEATING SHOULD YIELD SCATTERED TO NUMEROUS
SHRA/TSRA FRI THRU SUN. THE UPPER TROUGH WILL BEGIN TO WEAKEN AS
UPPER LEVEL RIDGING OVER THE SE U.S. BUILDS ACROSS THE NORTHERN
GULF. THE FIRST HALF OF LABOR DAY WEEKEND LOOKS RATHER WET WITH
SOME DRYING BY NEXT MONDAY. 43

MARINE...
NO CAUTION OR ADVISORY CONCERNS THROUGH THE END OF THE WEEK. HIGH
PRESSURE OVERHEAD TODAY WILL DRIFT WESTWARD AND ALLOW AN EASTERLY
FLOW TO DEVELOP BY LATE TUESDAY OR EARLY WEDNESDAY. SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS ARE POSSIBLE TODAY AND THURSDAY
AS AN UPPER LEVEL TROUGH MOVES OVERHEAD AS WELL. BY FRIDAY
SOUTHEASTERLY WINDS ARE EXPECTED TO DEVELOP.

40

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      76  97  75  96  75 /  10  30  20  10  10
HOUSTON (IAH)              76  95  76  94  76 /  20  50  20  20  20
GALVESTON (GLS)            80  90  82  91  82 /  30  60  40  40  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.

&&

$$

DISCUSSION...45
AVIATION/MARINE...38



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