MS-150 Houston-Austin Weather Outlook

[wxman57]

As some of you are aware, the annual MS-150 bike ride from Houston to Austin is scheduled for this coming weekend. I've been monitoring the weather closely for the past few weeks and have seen quite a few changes in the model projections for this weekend. Unfortunately, the latest trend does not look good at all for Saturday.

For over a week, the various models have indicated a cold front across TX on Saturday. Yesterday's morning model runs had a moderate cold front moving through Friday evening to very early Saturday with clearing weather for the ride. Later runs yesterday slowed the front down and kept Saturday cloudy, windy and cool.

As I look at the latest NWS forecast for Saturday I see partly cloudy and mid 70s with a chance of Afternoon thunderstorms. I can't imagine what they're looking at, as all model runs now indicate a rather deep upper low right over SE TX on Saturday, meaning cloudy, windy and cold with light rain.

In fact, the overnight GFS has the weather for Saturday's ride as cloudy with a start temp in the mid 50s with light rain. Wind from the NNW at 15-20 mph and gusty. Rain holds in until mid afternoon but the clouds don't clear out until Sunday. The high on Saturday may only be near 60 degrees with the clouds and precip.

That kind of weather won't stop the ride, but a lot of people may elect not to ride on Saturday. Rain would make the roads wet and quite dangerous, not to mention the strong headwind and cold temps.

Sunday is looking sunny and cool with a temp in the upper 40s for the start in La Grange, 10 mph north wind and a high around 72 by 3pm.

Let's hope that something changes between now and Saturday, or the first day of the ride will be extremely miserable and dangerous.

[wxman57]

The ride is 85-100 miles from Houston to La Grange on Saturday then about 75 miles to Austin on Sunday. Front would have to move a LOT slower than just 12-18 hrs. Better option would be faster and weaker, as per the 00z Canadian - but it's the outlier.

[wxman57]

Yes, at least the 12z GFS ends the rain early Saturday morning. Waiting to see if the Euro has made the change to an earlier front, too. I won't be riding - too many people. The wife is planning to ride. It won't be pleasant on Saturday. Ideal biking temps would be upper 70s to 85, not the mid 50s. Runners like it cold, cyclists don't because we're always facing 20-30 mph wind.

[srainhoutx]

Looks mighty breezy from the NW for the Saturday journey into La Grange...

[wxman57]

The past 24 hours have seen quite a change in the computer models we look at to help to forecast the weather. Up until yesterday morning, the 3 main models we use were all in good agreement that the cold front would move through Friday evening and Saturday would be rain-free. Since then, all 3 models have gone their separate ways, forecasting 3 completely different outcomes for Saturday. One (Canadian) says a weak front with no rain Friday or Saturday, another says cool and windy Saturday but no rain (GFS) and the other (European) says rain through Saturday evening. Until the models come into better agreement, my forecast confidence is low for Saturday. I don’t think that the model agreement will come until maybe Thursday morning.

Some good news, as of 5PM this afternoon, only 1 of those 3 models (the European) still has rain during the day on Saturday. Just got a new run of the American GFS model in and that’s 2 runs in a row with no rain on Saturday. Based on the latest data, this is what I’m thinking. And keep in mind my confidence on precisely when the rain will stop on Saturday is still on the low side.

Friday: Cold front approaches La Grange late afternoon. I expect a line of storms to move through during the evening. Rain could last 3-4 hours. Perhaps 1-2 inches. Chance that some storms could produce gusty winds.

Saturday: Line of showers/storms moves through Houston during the early morning hours (between 11pm Friday and 4am Saturday). Once the line moves through, the rain should end. In this scenario, the roads would be dry for the start of the ride. I’m not sure when the clouds might break out Saturday. I wouldn’t expect much sun in the morning, at the very least. Possibly some breaks during the afternoon, though.

Temperatures: Should start out in the 55-58 degree range at 7am. With lots of cool air flowing south across the route (and with the clouds), the temperature will rise only very slowly. By noon, it’s possible that the temperature will top 60 degrees. Maybe 63-64 degrees by 3pm. I see that the local NWS office is still saying mid 70s for Saturday’s high. I have no idea why they’re going so warm given the current data.

Wind: I think that whether or not the rain ends early, it looks to be a quite windy day. Wind will be from the NW-NNW at a good 15-18 mph with gusts as high as 30 mph. That means quite a headwind for the riders. Not much change in the wind through the ride, and the wind could even gust above 30 mph atop some of the hills on the open farm-to-market roads.

Given the above, I suspect that many will elect to use the SAG wagons. Hope they have plenty of extra SAGs on hand.

Sunday: Good news here is that Sunday will be a lot better than Saturday. Should be plenty of sunshine. No rain.

Temperature: Morning low in La Grange may hit 48 degrees, but the temperature should rise a lot more quickly than on Sunday. Could reach the upper 50s by 10am and the mid to upper 60s by noon then a high in the 72-75 degree range by 3pm in Austin.

Wind: From the north to NNE at 6-12 mph and not very gusty. This will be mostly a cross-wind. Considerable improvement over Saturday.

[srainhoutx]

It's always good to see wxman57 forecasting for the MS-150. It is tradition after all...

Squall line via the longer range 00Z WRF NMM

[wxman57]

No change to my forecast this morning. The Euro has come around to the GFS' thinking, ending the rain well before the ride start. Cool and WINDY Saturday, but should be dry.

[srainhoutx]

Morning e-mail from Jeff:

Upper air pattern will become highly amplified for mid April this weekend sending a strong low pressure system and cold front through TX on Friday.



At the surface winds will swing around to the south later today starting the return of Gulf moisture back into the region ahead of a late Friday frontal passage. Air mass will moisten on Friday, but forecast soundings show a decent capping inversion in place and very dry mid level air mass. With that said, the incoming front will have strong lift and the boundary will be moving through at least part of the area during peak heating. Feel at least a few strong to severe thunderstorms will develop along a thin band of convection with the boundary. Best chances for any severe weather will be from roughly Galveston to Katy to College Station and southwestward into deep S TX where instability will be greatest.



This system is fairly fast moving and should clear the area before sunrise Saturday. The surface low will begin to deepen over the NC Gulf of Mexico Saturday while strong high pressure builds into TX from the north. A very tight pressure gradient will be in place Saturday over eastern TX producing strong winds. Additionally, clearing skies will allow downward momentum transfer of some higher winds aloft during the day. Expect winds to rapidly come up Saturday morning out of the north into the 15-25mph range and then increase into the 20-30mph range by early afternoon with gust at or above 40mph. Cold air advection on Saturday will keep highs only near 70 (about 10 degrees below average) even under full sun.



Extended:

Cool surface high pressure will settle over the region Sunday with lows falling into the 50’s and possibly upper 40’s in some locations and highs in the mid 70’s. Nice weather with low humidity will continue into early next week.



Fire Weather:

Very strong winds expected on Saturday across the area along with low afternoon RH values in the 20-30% range. Typically this would be of some concern, but wet grounds and healthy vegetation cover should mitigate any significant fire weather concerns.



MS 150:

All storms will be east of the area by Saturday morning, but very strong winds out of the N and NW will blast the route all day Saturday. Winds will rapidly increase Saturday morning and remain strong and gusty all day sustained in the 20-30mph range and at times gusting 35-40mph. Air mass will be very dry with low RH and temperatures in the 60’s to lower 70’s. Sunday should feature calmer winds early, then breezes picking back up out of the N and NE by late morning into the 10-15mph range.



SPC Day 2 (Friday) Severe Weather Outlook:

[tireman4]

Good luck to those participating!!!

[wxman57]

All model guidance remains in good agreement on bringing the cold front through southeast Texas well in advance of the start of the ride Saturday morning. A line of showers/thunderstorms will move through La Grange between 6pm-10pm Friday evening then through the west Houston ride start points between 11pm and 3am. Expect between 0.5 inch and 1.5 inches when the line of showers moves through La Grange and west Houston. By the time the ride starts at 7am, the roads should all be dry.

The main weather impact on the riders will be the wind on Saturday. A headwind of 15-20 mph gusting to 25-30 mph is quite significant, particularly for the less experienced riders on heavier bikes. Fortunately, the wind will die down significantly Saturday night. Sunday will be a beautiful day, though a bit chilly at the start.

Saturday: (Houston to La Grange)
Showers should end about 3-4 hours before the start of the ride. Clouds decreasing through the morning, becoming partly cloudy by the time the riders reach the lunch stop in Bellville.
Wind (including La Grange): NNW 15-20 gusting 25-30 mph, decreasing to NNW-N 12-17 gusting 22 late afternoon and down to 5-10 mph by evening.
Temperature: 53-56 degrees at the start of the ride. Up to 62-64 degrees at lunch in Bellville and reaching a high of 68-70 degrees by 3pm in La Grange.
Probability of rain: No rain expected during the ride.

Sunday: (La Grange to Austin): Mostly clear and milder after a cool early morning start to the day.
Wind: N 2-7 mph, increasing to NNE 7-12 mph by midday
Temperature: Around 48 degrees at the start of the ride, increasing to 71-73 degrees by the time the riders reach the lunch stop in Bastrop and up to 77-79 degrees at the end of the ride in Austin.
Probability of rain: 0%