FXUS64 KCRP 061139 AAA
AFDCRP
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
539 AM CST SUN DEC 6 2009
.DISCUSSION...SEE AVIATION SECTION.
&&
.AVIATION...CEILINGS ARE LOWERING BEHIND THE WARM FRONT OR COASTAL
TROUGH ALONG THE COAST AS MOISTURE CONTINUES TO RIDE OVER THE
SHALLOW COOL AIRMASS OVER SOUTH TEXAS. MVFR CEILINGS IN THE RANGE
FROM 2000-2500 FT WILL DEVELOP OVER THE COASTAL PLAINS LATER THIS
MORNING WHILE LOWER MVFR CEILINGS AROUND 1500 FT OVER THE WESTERN
BRUSH COUNTRY LIFT LATER THIS MORNING AS DRIER MOVES IN FROM THE
WEST. A STRONG LOW LEVEL SOUTHERLY FLOW OVER THE COASTAL PLAINS
WILL PROVIDE A CHANCE FOR LIGHT RAIN THIS MORNING INTO EARLY THIS
AFTERNOON AS A WEAK UPPER LEVEL DISTURBANCE ALSO MOVES THROUGH. A
BRIEF IMPROVEMENT IN THE CEILINGS IS EXPECTED IN THE AFTERNOON
BEFORE THE COASTAL TROUGH/FRONTAL BOUNDARY SLIDES BACK INTO THE
GULF. WITH THE SURFACE HIGH PRESSURE SETTLING INTO THE REGION THIS
EVENING...EXPECT CEILINGS TO LOWER TO IFR AND AREAS OF FOG TO
DEVELOP AROUND MIDNIGHT. LIFR/VLIFR CONDITIONS WILL BE POSSIBLE
OVER THE INLAND COASTAL PLAINS BY 08Z MONDAY.
&&
.PREV DISCUSSION... /ISSUED 407 AM CST SUN DEC 6 2009/
SHORT TERM (TODAY THROUGH MONDAY)...WATER VAPOR IMAGERY SHOWS
A WEAK MID/UPPER LEVEL SHORT WAVE TROUGH JUST SOUTH OF THE TEXAS
BIG BEND MOVING EAST. AS THIS SHORT WAVE TROUGH MOVES ACROSS
SOUTH TEXAS THIS MORNING...GFS/NAM SHOW 925-850 MB WARM AIR
ADVECTION INCREASING WITH A SOUTHERLY FLOW OF 30-40 KNOTS. THE
ISENTROPIC UPGLIDE INCREASES SUBSTANTIALLY IN THE 290-300K
LAYER THIS MORNING OVER THE COASTAL PLAINS. LATEST KCRP RADAR
LOOP SHOWS LIGHT PRECIP DEVELOPING AND EXPECT THIS TO CONTINUE
THROUGH THE MORNING HOURS. STRONGEST WARM AIR ADVECTION AND
LONGER PERIOD WITHIN ISENTROPIC UPGLIDE WILL REMAIN OVER THE
MID-COAST REGION...WILL SHOW 50 PERCENT POPS THERE AND TAPER
BACK TO SLIGHT CHANCE OVER THE EASTERN BRUSH COUNTRY AND
NOTHING FOR THE WESTERN BRUSH COUNTRY TODAY. COASTAL TROUGH
OR WARM FRONT IS HUGGING THE COAST EARLY THIS MORNING AND
MAKES FOR A TRICKY FORECAST WITH REGARDS TO THE TEMPS/WINDS.
EXPECT THE BOUNDARY TO MOMENTARILY MOVE INLAND THIS MORNING
BUT THE TROUGH SHOULD MOVE BACK INTO THE COASTAL WATERS BY
LATE THIS AFTERNOON WITH WINDS SHIFTING BACK AROUND TO THE
NORTHEAST. WENT CLOSE TO THE NAM ACROSS NORTHERN SECTIONS
AND COMPROMISED BETWEEN THE NAM AND GFS FOR SOUTHERN SECTIONS.
AS THE SHORT WAVE TROUGH EXITS TO THE EAST ALONG WITH THE
LOW LEVEL WARM AIR ADVECTION/ISENTROPIC LIFT...RAIN CHANCES
WILL DIMINISH OVER THE AREA THIS EVENING. SKIES MAY BRIEFLY
BREAK OUT ACROSS THE WESTERN COUNTIES...BUT ISENTROPIC
UPGLIDE DEVELOPS AGAIN OVERNIGHT AND CLOUDS SHOULD COVER
MOST OF SOUTH TEXAS LATE TONIGHT THROUGH MONDAY. EXPECT AREAS
OF FOG TO FORM OVER THE REGION AFTER MIDNIGHT AND CONTINUE
INTO MONDAY MORNING. THE ISENTROPIC LIFT INCREASES DURING
THE DAY MONDAY BUT IS NOT QUITE AS STRONG AS TODAY ALONG
WITH THE ABSENCE OF A SIGNIFICANT SHORT WAVE TROUGH TO
ASSIST. BROADBRUSHED 20-30 PERCENT CHANCE POPS FOR THE
AREA FROM WEST TO EAST AND CONTINUED TO UNDERCUT GUIDANCE
FOR MAX TEMPS MONDAY.
LONG TERM (MONDAY NIGHT THROUGH SATURDAY)...THE MEDIUM RANGE GFS
AND ECMWF MODELS ARE VERY MUCH IN AGREEMENT THROUGH MUCH OF THE
EXTENDED FORECAST PERIOD. IN THE MONDAY NIGHT/TUESDAY TIMEFRAME, AN
OPEN TROUGH ALOFT WILL MOVE EASTWARD THROUGH THE CENTRAL/SOUTHERN
PLAINS BRINGING CHANCE POPS TO THE ENTIRE FORECAST AREA MONDAY NIGHT
WITH SLIGHT CHANCE POPS BECOMING LIMITED TO THE FAR EASTERN PORTION
OF THE FORECAST AREA TUESDAY AFTERNOON AS THE UPPER TROUGH PASSES TO
OUR EAST. A MODERATELY STRONG COLD FRONT ASSOCIATED WITH THE UPPER
TROUGH WILL PASS ACROSS THE FORECAST AREA TUESDAY NIGHT FOR CLEARING
SKIES, SOME COLD AIR ADVECTION, AND STRONG OFFSHORE FLOW. ON
WEDNESDAY, QUASI-ZONAL FLOW WILL PREVAIL ALOFT AS SURFACE HIGH
PRESSURE SETTLES OVER CENTRAL TEXAS WITH DRY CONDITIONS EXPECTED.
QUASI-ZONAL FLOW AND DRY CONDITIONS WILL CONTINUE INTO THURSDAY AS
SURFACE HIGH PRESSURE MOVES OFF TO THE EAST AND A WEAK RETURN FLOW
DEVELOPS. SLIGHT CHANCES OF PRECIPITATION WILL BE IN STORE FOR MUCH
OF THE FORECAST AREA THURSDAY NIGHT/FRIDAY AS ANOTHER WEAK UPPER
TROUGH PASSES BY TO OUR NORTH AND PUSHES AN ASSOCIATED COLD FRONT
INTO SOUTH TEXAS ONCE AGAIN. THE ECMWF SHOWS THE UPPER TROUGH TO BE
SOMEWHAT STRONGER THAN THE GFS AND THIS IS WHERE THE FIRST REAL
DIFFERENCE IN THE MODEL SOLUTIONS APPEAR. WHILE THE GFS AND ECMWF
BOTH SHOW QUASI-ZONAL FLOW FOR SATURDAY, THE GFS INDICATES WEAK
ONSHORE FLOW REDEVELOPING WHILE THE ECMWF SHOWS A DRYING
POST-FRONTAL NORTHERLY FLOW. CONSIDERING THE PROGRESSIVE NATURE OF
THE OVERALL UPPER PATTERN ACROSS THE U.S., THE GFS SOLUTION SEEMS
MORE REASONABLE AND WILL STRUCTURE THE FORECAST FOR THE REMAINDER OF
THE LONG TERM ON THIS MODEL. TEMPS TO REMAIN AT OR SOMEWHAT ABOVE
NORMAL THROUGH THE FIVE DAY PERIOD.
MARINE (TODAY THROUGH MONDAY)...THE COASTAL TROUGH/WARM FRONT
IS ALONG THE COAST AND WITH STRONG LOW LEVEL FLOW...SOME OF THE
HIGHER MOMENTUM IS MIXING DOWN OVER THE WARMER GULF WATERS. EXPECT
THE WINDS TO INCREASE TO AROUND 20 KNOTS OVER THE OFFSHORE WATERS
LATER THIS MORNING AND CONTINUE INTO EARLY AFTERNOON BEFORE THE
GRADIENT RELAXES AS THE COASTAL TROUGH MOVES BACK OVER THE WATERS.
SCATTERED LIGHT SHOWERS WILL BE POSSIBLE TODAY AND AGAIN MONDAY
WITH THE COASTAL TROUGH MOVING OFFSHORE AND WINDS BECOMING
NORTHEAST OVER THE GULF WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 62 55 63 58 74 / 40 10 30 40 20
VICTORIA 58 46 58 55 70 / 50 20 30 50 30
LAREDO 68 52 65 55 80 / 10 10 20 30 10
ALICE 64 52 62 57 76 / 30 10 30 40 20
ROCKPORT 64 54 64 59 73 / 40 10 30 50 20
COTULLA 63 46 59 53 76 / 10 10 20 30 10
KINGSVILLE 66 54 64 57 78 / 30 10 30 40 20
NAVY CORPUS 65 56 65 61 74 / 40 10 30 40 20
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR THE
FOLLOWING ZONES: WATERS FROM BAFFIN BAY TO PORT ARANSAS
FROM 20 TO 60 NM...WATERS FROM PORT ARANSAS TO MATAGORDA
SHIP CHANNEL FROM 20 TO 60 NM.
&&
$$
TMT/89...SHORT TERM/AVIATION
JAR/19...LONG TERM
