IT IS NOT QUITE AS COLD HAS IT HAD BEEN THIS MORNING. TEMPERATURES ARE STILL IN THE LOW 30S FOR MOST AREAS ACROSS SE TX WITH A FEW SPOTS BELOW FREEZING. STILL THIS IS 5-10 DEGREES WARMER THAN YESTERDAY MORNING. WEAK SFC RIDGE STILL OVER THE UPPER TX COAST HAS ALLOWED FOR MOSTLY CLEAR SKIES AND CALM WINDS OVER THE REGION THIS MORNING. HIGH PRESSURE OVER THE MIDWEST THIS MORNING WILL SLIDE TOWARDS THE MISS RIVER VALLEY TODAY WITH A WEAK FRONTAL BOUNDARY STALLING OFF TO THE NE OF SE TX. EVEN WITH SOME CLOUD COVER...TEMPERATURES TODAY WILL STILL WARM INTO THE 50S AND THIS WARMING TREND SHOULD CONTINUE THROUGH THE END OF THE WEEK.
SPLIT JET UPPER LEVEL PATTERN WILL CONTINUE. TROUGHING WILL REMAIN OFF TO THE NORTHEAST AS A WEAK UPPER LEVEL LOW OVER NORTHERN MEXICO CONTINUES TO UNDERCUT RIDGING OVER THE ROCKIES. THIS UPPER LEVEL LOW WILL NOT CAUSE MUCH IN THE WAY OF WEATHER EXCEPT FOR CLOUD COVER AND MAYBE SOME LIGHT RAIN LATE WEDNESDAY. THIS TROUGH WILL SHEAR OUT THU AS ANOTHER DEEP TROUGH DEVELOPS OVER NOR MEXICO WITH A FAIRLY POTENT JET STREAK AND VORTICITY MAX PUSHING INTO IT. THIS MAY CAUSE THE UPPER LOW TO DROP A LITTLE FARTHER SOUTH THAN WHAT SOME OF THE MODELS EXPECT. AT THIS TIME...THE SLIGHTLY SLOWER AND MORE CONSISTENT ECMWF SEEMS TO BE THE BETTER SOLUTION THAN THE GFS. REGARDLESS OF MODEL CHOICE...EXPECT SHOWERS TO DEVELOP THU WITH STRONG ISENTROPIC LIFT AS SFC CYCLOGENESIS INCREASES JUST OFF THE COASTAL BEND. THE 00Z GFS HAS THIS COASTAL LOW FARTHER SOUTH THAN PREVIOUS SOLUTIONS AND MAY BE DUE TO IT KEYING IN ON CONVECTION. STILL...DIFFLUENCE FROM THE TROUGH AND ISENTROPIC LIFT SHOULD BE ENOUGH FOR SHOWERS THU AND THU NIGHT. INSTABILITY MAY BE HARD TO COME BY FOR THUNDERSTORMS BUT FORCING MAY BE ENOUGH FOR CONVECTIVE VERTICAL MOTIONS. THE 00Z CANADIAN AND ECMWF REALLY HIT PRECIP HARD FOR 12Z FRI WHERE LIFT IS MAXED OUT AND THE COASTAL LOW STARTS TO DEEPEN. DECIDED TO GO WITH 80 POPS FOR THE WHOLE AREA BUT THIS MAY BE A TAD HIGH FOR THE NORTHERN THIRD OF SE TX. THE 12Z FRI TO 00Z SAT SEEMS TO BE THE BEST CHANCES FOR RAINFALL AND SOME COULD BE HEAVY RAINFALL WITH ANY FORCED CONVECTION. FLOODING DOES NOT APPEAR TO BE A PROBLEM AS MOST AREAS WILL PROBABLY HAVE RAINFALL AMOUNTS OF 1 TO 3 INCHES. PRECIP WATER VALUES ONLY TOP OUT AROUND 1.2-1.3 INCHES WHICH WOULD BE A COUPLE TENTHS SHY OF 2 STANDARD DEVIATIONS FROM NORMAL. ALL SAID AND DONE...WILL NEED TO MONITOR FOR THE POSSIBILITY OF ISOLATED HIGHER AMOUNTS OF RAINFALL THAT COULD INCREASE THE FLOOD THREAT. THIS OTHER THREAT TO MONITOR WILL BE COASTAL FLOODING FOR THE COASTS OF GALVESTON AND BRAZORIA COUNTIES. STRONG EAST WINDS AND A LONG FETCH WILL BUILD UP WAVE ACTION AND TIDE LEVELS. COASTAL FLOOD STATEMENTS MAY BE NEEDED BUT LARGELY DEPEND ON HOW THE COASTAL LOW DEVELOPS AND ITS INTENSITY.
SATURDAY LOOKS TO HAVE WRAP AROUND PRECIP ON THE BACK SIDE OF THE UPPER LOW AS IT MOVES EAST ACROSS THE AREA INTO S LA. REALLY SHOULD JUST SEE LIGHT RAIN AND COLD WITH HIGH TEMPS IN THE 40S/50S. THE RAIN SHOULD COME TO AN END QUICKLY SAT NIGHT WITH DRY CONDITIONS ON SUN. SUN MORNING WILL LIKELY HAVE LOW TEMPS IN THE 30S BUT DO NOT ANTICIPATE FREEZING TEMPS. MAX TEMPS ON SUN AND MON WILL MODIFY NICELY BACK CLOSE TO CLIMO NORMS.
Here's the NWS hourly projection for Marathon Sunday. The NWS projects 38°F at the start and 47°F at 10AM, with the dewpoint in the 30s. That's nearly perfect for me. They have a NW wind at 7 mph to a NNW wind at 6 mph and partly cloudy with sky cover going from 32% to 29%.
The 7.5-day model includes marathon morning. This model follows right along with the NWS hourly projection [the graph is in UTC, six hours ahead of Houston]. The text version of the MRF model. shows a low of 40°F and strong winds (17mph) in the morning.
The Weather Channel tends to weight their long term predictions with seasonal averages. For Saturday night they show:
Overnight Low 41°F
Precip 20%
Wind: NW 8 mph
Max. Humidity: 82%
Clouds Early/Clearing Late
For Sunday they show:
High 59°F
Precip 0%
Wind: WNW 6 mph
Max. Humidity: 72%
UV Index: 4 Moderate
Sunrise: 7:17 AM CT
Partly Cloudy
AccuWeather has Saturday night on their 5-day forecast. and Sunday on their 6 to 10 day forecast. They predict:
Saturday Night, Jan 16
Low: 41 °F RealFeel®: 34 °F
Winds NNW at 11 mph with gusts to 23 mph
Partly cloudy
Sunday, Jan 17
High: 58 °F RealFeel®: 58 °F
Warmer with sunshine and some clouds
Here's a story from Let'sRun/the Marathon on the elites that will be lining up Sunday.
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