165  
FXUS64 KHGX 210300  
AFDHGX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX  
900 PM CST SAT JAN 20 2018  
   
UPDATE
 
 
CURRENT RADAR IMAGERY SHOWS A FEW LIGHT SHOWERS SITUATED OVER  
FORT BEND, HARRIS, AND LIBERTY COUNTIES WITH THE OCCASIONAL  
DRIZZLE ACROSS THE COASTAL TIER OF COUNTIES. AS THE NEXT COLD  
FRONT APPROACHES THE REGION, THE POTENTIAL FOR SHOWER DEVELOPMENT  
WILL BEGIN IN OUR NORTHERN MOST COUNTIES FROM HOUSTON TO MADISON  
TO BURLESON DURING THE OVERNIGHT HOURS. OTHERWISE, SHOWER COVERAGE  
SHOULD CONTINUE TO DIMINISH LATE SATURDAY INTO EARLY SUNDAY  
ACROSS I-10 AND SOUTHWARD.  
 
CLOUD COVER WILL CONTINUE TO THICKEN ACROSS THE REGION AND INTO  
SUNDAY MORNING. MINOR CHANGES TO THE FORECAST TONIGHT TO ACCOUNT  
FOR TRENDS IN OBSERVATIONS FOR CLOUD COVER AND TEMPERATURES.  
LOWERED MINIMUM TEMPERATURES BY A DEGREE OR TWO TONIGHT IN THE  
NORTHERN COUNTIES WHERE CLOUD COVER IS NOT AS THICK, AND RAISED  
TEMPERATURES ACROSS THE HOUSTON METRO WHERE CLOUD DECKS HAVE  
FILLED IN BECOMING OVERCAST. DEWPOINTS HAVE REBOUNDED NICELY WITH  
THE HELP OF ONSHORE FLOW, AND HAVE NUDGED UP DEWPOINTS SLIGHTLY TO  
ACCOUNT FOR CURRENT OBSERVATIONS. WITH THIS RETURN MOISTURE, THE  
THREAT FOR SEA FOG IS PRESENT AGAIN THIS EVENING ACROSS THE BAYS  
AND NEARSHORE WATERS. SPECIFICALLY, PATCHY TO DENSE FOG  
CONDITIONS ARE POSSIBLE TONIGHT IN GALVESTON BAY. AREAS OF FOG ARE  
EXPECTED ACROSS SE TX TONIGHT, WITH THE BEST CHANCE FOR  
DEVELOPMENT AGAIN IN OUR WESTERN ZONES.  
 
HATHAWAY  
 

 
   
PREV DISCUSSION
 
/ISSUED 547 PM CST SAT JAN 20 2018/  
 
AVIATION [00Z TAF ISSUANCE]...  
 
RADAR SHOWING A WEAK TRAINING LINE OF SHOWERS FROM KLBX TO EAST  
OF KHOU. SHOWERS MAY GO RIGHT OVER KLBX AND CAUSE LOWER VISIBILITY  
DURING RAIN ALONG WITH LOWER CEILINGS. AS A WHOLE CEILINGS ARE  
SITTING AT MVFR/VFR LEVELS WITH THE EXPECTATION OF BKN/OVC MVFR  
CEILINGS DEVELOPING IN THE NEXT 3 TO 6 HOURS. KHGX VAD WIND  
PROFILE SHOWS BASICALLY 20-25 KNOTS THROUGH THE LOWEST FEW  
THOUSAND FEET OF THE BOUNDARY LAYER. MODEL GUIDANCE SHOWS LLJ  
INCREASING TO AROUND 30-35 KNOTS TONIGHT OVER THE NEXT 6 HOURS.  
SFC WINDS SHOULD ALSO REMAIN AROUND 7-10KTS ACROSS THE AREA WITH  
VERY LITTLE IF ANY DECOUPLING. IF THIS OCCURS, CEILINGS WILL  
LIKELY STAY IN THE LOW MVFR MAYBE HIGH IFR CATEGORIES AND  
VISIBILITY FROM FOG MAY ONLY BE 3-6SM. AS SUCH MOST TAFS HAVE  
CEILINGS DROPPING TO MVFR WITH MAYBE A FEW HOURS OF IFR DURING  
THE DAYBREAK HOURS HANDLED WITH A TEMPO GROUP. WINDS THEN MIX DOWN  
LATE MORNING HOUR SO EXPECTING TOMORROW TO BE WINDY WITH CEILINGS  
INCREASING TO MVFR/VFR LEVELS. IN THE EXTENDED PORTION OF THE  
TAFS, COLD FRONT EXPECTED SUNDAY NIGHT SHOULD BE CLOSER TO THE  
06-12Z MONDAY TIME FRAME SO MAY NEED A LINE FOR FROPA IN THE IAH  
TAF FOR THE 06Z TAF UPDATE.  
 
OVERPECK  
 
PREV DISCUSSION /ISSUED 331 PM CST SAT JAN 20 2018/...  
 
WARMER AND HUMID CONDITIONS WITH PERIODS OF RAIN AND FOG WILL  
CONTINUE ACROSS SOUTHEAST TEXAS THROUGH SUNDAY BEFORE A COLD FRONT  
USHERS IN DRIER AND SOMEWHAT COOLER AIR MONDAY. THE KHGX RADAR  
THIS AFTERNOON SHOWS A THIN BAND OF SHOWERS STRETCHING FROM NEAR  
MOSS HILL TO SAN LEON. WITHIN THE BAND, ISOLATED ONE-HALF INCH TO  
ONE INCH AMOUNTS HAVE BEEN OBSERVED AS THIS ACTIVITY CONTINUES TO  
MOVE TOWARDS THE NORTHEAST. BEHIND THE BAND, WARM AIR ADVECTION  
HAS LED TO NOT ONLY RENEWED DEVELOPMENT OF ISOLATED SHOWERS BUT  
HAS PROMOTED AFTERNOON TEMPERATURES INTO THE LOW TO MID 70S  
SOUTHWEST OF THE HOUSTON METRO. THIS WARM AIR ADVECTION WILL KEEP  
THE POTENTIAL FOR A FEW SHOWERS IN THE FORECAST THROUGH SUNDAY AS  
WELL AS ONLY ALLOW OVERNIGHT LOWS TO FALL INTO THE LOWER 60S. FOG  
IS EXPECTED AGAIN INLAND OVERNIGHT BUT STRONGER WINDS MAY PRECLUDE  
OR SHORTEN ANY DENSE FOG DEVELOPMENT.  
 
AFTERNOON WATER VAPOR IMAGERY SHOWS AN UPPER TROUGH STRETCHING  
FROM THE GREAT BASIN DOWN TOWARDS BAJA CALIFORNIA AND AS THIS  
FEATURE REACHES THE SOUTHERN PLAINS SUNDAY, A LEE SURFACE LOW  
WILL RESULT IN BREEZY SOUTHERLY WINDS DURING THE DAY SUNDAY AS AN  
ASSOCIATED PACIFIC FRONT PUSHES ACROSS NORTH AND CENTRAL TEXAS  
AND TOWARDS THE REGION. THE ARRIVAL OF A 120 KNOT UPPER LEVEL JET  
STREAK SUNDAY AFTERNOON WILL NOT ONLY HELP THE LEE CYCLONE EJECT  
ACROSS THE SOUTHERN PLAINS, BUT WILL PROVIDE ENOUGH LIFT FOR  
THUNDERSTORMS TO DEVELOP ALONG THE PACIFIC FRONT AS IT SLIDES INTO  
THE REGION. WHILE THE BEST JET DYNAMICS ASSOCIATED WITH THIS  
FEATURE LOOK TO REMAIN ACROSS NORTH TEXAS AND THE ARK-LA-TEX, MID-  
LEVEL LAPSE RATES STEEPENING TO NEAR 7 C/KM INDICATE THE  
POTENTIAL FOR ENOUGH UPDRAFT ACCELERATION TO PROMOTE A GUSTY WIND  
THREAT. THIS IS CONTINGENT ON THUNDERSTORMS BEING ABLE TO DEVELOP,  
HOWEVER, AS INCREASING DEEP SOUTHWESTERLY FLOW MAY RESULT IN A  
BUILDING CAP AND CLOUD COVER MAY FURTHER INHIBIT INSTABILITY...  
ULTIMATELY LIMITING HOW FAR SOUTH ALONG THE PACIFIC FRONT ACTIVITY  
IS ABLE TO BUILD. AS OF NOW, EXPECT THE BEST POTENTIAL FOR ANY  
STRONG TO POSSIBLY SEVERE THUNDERSTORMS TO BE NORTH OF A COLLEGE  
STATION TO LIVINGSTON LINE. THIS AFOREMENTIONED CAPPING MAY ONLY  
ALLOW A THIN BAND OF SHOWERS TO DEVELOP FARTHER SOUTH ALONG THE  
PACIFIC FRONT BEFORE IT IS OVERTAKEN BY A SECONDARY COLD FRONT  
SUNDAY NIGHT. TEMPERATURES SUNDAY AFTERNOON ARE EXPECTED TO RISE  
INTO THE LOW TO MID 70S AHEAD OF BOTH FRONTS.  
 
EXPECT THE COLD FRONT TO MOVE OFF THE COAST MONDAY MORNING AND  
SHUNT ANY REMAINING SHOWERS OR THUNDERSTORMS INTO THE COAST WITH  
IT, LEAVING BREEZY AND DRIER CONDITIONS IN ITS WAKE ON MONDAY.  
HIGHS MONDAY THROUGH MID-WEEK WILL REMAIN IN THE MID TO UPPER 60S,  
MODERATING ONLY SLIGHTLY INTO THE LOWER 60S AS A BACKDOOR FRONT  
ARRIVES ON WEDNESDAY. RAIN CHANCES DON'T RETURN TO THE FORECAST  
UNTIL THE BEGINNING OF THE WEEKEND AS ONSHORE FLOW ALLOWS FOR GULF  
MOISTURE TO RETURN BACK INTO THE REGION.  
 
HUFFMAN  
 
MARINE...  
PERIODS OF SHOWERS AND SEA FOG ARE EXPECTED ACROSS THE WATERS  
UNTIL A COLD FRONT PUSHES OFF THE COAST LATE SUNDAY NIGHT/EARLY  
MONDAY MORNING. THE SEA FOG MAY BECOME DENSE AT TIMES. CAUTION  
FLAGS WILL LIKELY BE REQUIRED BOTH FOR MODERATE ONSHORE FLOW AHEAD  
OF THE FRONT AS WELL AS MODERATE OFFSHORE WINDS IN THE WAKE OF  
THE FRONT. NW WINDS IN THE IMMEDIATE WAKE OF THE FRONT WILL  
GRADUALLY BECOME ENE BY TUESDAY. CAUTION FLAGS MAY BE REQUIRED AT  
TIMES THROUGHOUT THE WEEK. ANOTHER FRONT WILL PUSH OFF THE COAST  
NEXT WEEKEND. 11  
 
FIRE WEATHER...  
A COLD FRONT WILL PUSH THROUGH THE REGION SUNDAY NIGHT, BRINGING  
DRY AND BREEZY CONDITIONS IN ITS WAKE. RELATIVE HUMIDITY COULD GET  
BELOW 30% WITH SUSTAINED NW WINDS OF 10 TO 15 MPH MONDAY  
AFTERNOON. TUESDAY WILL LIKELY BE DRY AS WELL, BUT WINDS SHOULD BE  
MUCH LIGHTER. FINER FUELS ARE ALREADY PRETTY DRY ACROSS THE  
REGION FOLLOWING THIS WEEK'S HARD FREEZE. ALTHOUGH A RED FLAG  
WARNING WILL LIKELY NOT BE REQUIRED, ELEVATED FIRE CONDITIONS WILL  
BE A CONCERN FOR MONDAY. 11  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
COLLEGE STATION (CLL) 59 74 47 65 37 / 20 50 60 0 0  
HOUSTON (IAH) 63 75 55 68 40 / 20 30 70 0 0  
GALVESTON (GLS) 62 70 57 68 46 / 20 20 60 10 0  
 

 
   
HGX WATCHES/WARNINGS/ADVISORIES
 
 
TX...NONE.  
GM...SMALL CRAFT SHOULD EXERCISE CAUTION THROUGH SUNDAY AFTERNOON FOR  
THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA  
SHIP CHANNEL FROM 20 TO 60 NM...WATERS FROM HIGH ISLAND TO  
FREEPORT FROM 20 TO 60 NM.  
 

 
 

 
 
UPDATE...08  
 
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