DFW: Cold front to bring cooler temps to N. Texas Saturday 9/10

These forecast updates can also be found on our Facebook page.  I have compiled them here for easy access as we track the first fall cold front, very early for North Texas, if this verifies.   Note: Scroll down the page to see previous updates dating back to 8/27…

Follow Up [Monday 9/12]

The following are reported low temperatures across North Texas

***Saturday night 9/10 was our coolest in over 3 months***
***50s reported over much of the area***
Nacona  54
Graham Arpt  55
Alvord  55
Bowie  56
Fort Worth/Alliance  56
Bridgeport  56
Denton  56
Mc Kinney  56
Hillsboro  57
Sherman/Denison  57
Paris/Cox Field  57
Gainesville  57
Cooper Dam  57
Weatherford  57
Arlington  58
Grapevine 58
Mineral Wells Muni  58
Greenville/Majors  59
Greenville  59
Granbury  60
Lancaster  60
Breckenridge  60
Dallas/Love Field  64
Midlothian/Waxac  60
Decatur  60
Sulphur Springs  60
Hillsboro  60
Cleburne  61
Dallas/Redbird Arpt  61
Terrell  61
Lampasas 15Wnw  61
Fort Worth/Meacham  61
Stephenville/Clark  61
Goldthwaite 10 Ene  61
Fort Worth Nature Center  61
Temple/Miller 63
Rockwall  63
Hamilton  63
Fort Worth Nas  63
Mesquite  63
Athens  63
Comanche County Arpt  63
Waco  64
DFW Airport 65

Previous Forecast Update [Thursday 9/8 at 4:30 pm]

…Forecast is still on track…
…Cold front #1 Saturday morning…
…Coolest night in 3 months Sat night…

I wanted to take some time to provide some forecast specifics and explain the source of some uncertainty in the long range…

  Cold front early Saturday…

• As I posted earlier today, the first cold front is still on track to move through N. Texas late Friday night/Saturday morning.

• Some of the new data have trended cooler, and are indicating low temperatures Saturday night as cool as the mid/upper 50s northwest of a McKinney to Fort Worth line, and lower 60s at DFW Airport and Dallas. This is not extreme by any means, but it is the coolest airmass that we’ve seen since May.

• Regarding the high temperatures on Saturday, they will certainly be significantly cooler than those of today/tomorrow. In fact, we should stay in the 70s most of the day thanks to clouds and rain. However, a brief pullback into the lower 80s late in the afternoon is possible if we see breaks in the overcast or partial clearing.

• Irrespective of the exact high temperature, be it in the upper 70s or lower 80s, that has been my predicted range for the past week and it represents temperatures 15-20 degrees cooler than today’s. That’s significant as far as I’m concerned, and it will feel great.

• The temperatures on Saturday, assuming perfect prog, would be 10-15 degrees below normal (the normal high is 90º, normal low is 70º).

• As is typical of September cool fronts, a warmup is inevitable. Mid 80s Sunday, mid-upper 80s (possibly near 90º) Monday/Tuesday.

  Rainfall on Saturday…
• I expect an area of rain to envelope the area Saturday morning, spreading from NW to SE. I continue to place rain chances at 90%, with rain ending by 2-3 pm north of I-20 (even earlier further north/west).

• Some embedded thunder is possible, but no severe weather.

  Why there has been uncertainty next week…
• I must admit uncertainty with the mid-week front. The front will exist, but there is a chance that it could stop moving before it reaches DFW.  The atmosphere is a fluid described by the complex equations of fluid motion, and a storm system 2000 miles away can trigger downstream processes that affect other features/processes via various feedback loops.  

• In this case, we have to consider a slow-moving upper-level trough, currently thousands of miles away, and how it may ultimately evolve as it approaches the Pacific Northwest.  There are signs that various atmospheric dynamics associated with the upper trough may cause it to deepen, possibly evolving into a closed upper low over the Pacific NW early next week. The form that it takes and the direction that it moves during its evolution will really determine what happens with the front.  

• If the upper trough evolves a certain way, it  *could* trigger the formation of an area of low pressure at the surface over NW Texas by Tuesday. When that happens, the surrounding wind field responds accordingly and the ensuing low-level flow tends to slow the forward speed of southbound cold fronts.  This means that next week’s front could stall between Wichita Falls and DFW. Quite frankly, the numerical models have a poor handle on it and their solutions will continue to flip flop until they do. We have to make the best forecast we can in the absence of reliable computer guidance. 

Note: I also want to reiterate that by no means would any cold front (even the one on Saturday) result in “cold” weather. That has never been expected or implied. We’re talking about typical early fall cool-downs. That has been well-communicated in all of my previous forecasts, but sometimes the wrong conclusions are drawn from brief headlines and colorful images.

• Let’s muddle through the hot weather today and tomorrow, then we have much cooler weather to look forward to on Saturday.

  Forecast summary…
Today/Friday: Just hot. Mid 90s
Saturday: Cold front early. Overcast. Rain likely. Brief periods of heavy rain is possible, with embedded thunder. No severe weather. Chance of rain 90%. High: upper 70s to lower 80s.   Lows in the 60s Saturday night, possible 50s northwestern 1/3.
Sunday: Sun. Mid 80s.
Mon/Tue: Sun. Lower 90s.
Wednesday: Cold front early. Increasing clouds with a chance of showers. Lower 90s.
Thursday: Overcast. Rain likely. Lower 80s.

Chris Robbins, Meteorologist, M.S., iWeatherNet.com


Fifth Update [Tuesday 9/6 at 12:50 am]

…Some of the recent model guidance has trended cooler…
…However, no forecast changes are needed at this time…

• I’m still amazed by the consistency that I’ve seen in the numerical prediction models since mid-August. Model solutions have consistently indicated this airmass arriving in North Texas during the week of September 12.

• Model consistency doesn’t guarantee accuracy, but consistency is something we look for when forecasting.

• The first cold front will move through on Saturday (9/10) with significantly cooler temperatures.  The magnitude of cooling behind the front will be a function of cold advection, overcast, and diabiatic cooling (evaporative cooling from rain).

• Instead of temperatures in the 90s on Saturday, like they will be the day prior, we believe they will struggle to reach 80º (this further assumes that our forecast of an early morning frontal passage and persistent overcast most of the day pan out as expected; as we say, the failure of one predicted element affects all others).  Parts of the area will stay in the 70s all day.

• A second front appears to come through Tuesday night/Wednesday (7 days from now), but we currently have much higher uncertainty since that time period is still a week away.  Updates will be added later this week.  Preliminary graphics are shown below.  Again, it’s important to read the details and embedded caveats — not just the headlines or graphics.

• All of the model solutions are in close agreement and line up with my own estimates/experience, particularly with the first front on Saturday.

• I generally shy away from posting model graphics, but this is the best way for me to illustrate the nature of this airmass. Today’s data have trended colder, and therefore no changes to my forecast are required.

• If we assume perfect prog, this front will be moving through North Texas during the day, with gusty winds and falling temperatures. We would also have low temperatures in the 50s, which is about 3 weeks earlier than normal (on average, our first low temperature below 60º occurs on/around October 8).

Chris Robbins, Meteorologist, M.S., iWeatherNet.com

Frontal Position & Temperatures Tuesday Afternoon (9/13)

Cold Front Forecast Position on Tuesday 9-13-16

Computer-simulated position of the second cold front Tuesday afternoon (9/13/16).  This is a very uncertain and climatologically unlikely scenario. We will keep an eye on it.


Fourth Update [Sunday 9/4]

I wanted to show an animated gif depicting temperature anomalies during the week of September 12 through the 18th.  The dark blue and purple represent temperatures 10 to 18 degrees below normal.  As a scientist, I have to admit some degree of uncertainty; since we are still 8-9 days out, I will wait another day or two before I pin down timing and exact temperatures.  However, I have been tracking this airmass and I have seen remarkable consistency within the data that I’ve analyzed for over 2 weeks now.  Therefore,  I have high confidence that the airmass will begin to move south in a few days and that North Texas will experience early fall weather next week (summer doesn’t end until the following week).

If this comes to fruition, it would be a rare event for mid-September in North Texas.  Climatologically speaking, our first day with low temperatures below 60ºF at DFW is October 8; we were close to that last year since we didn’t fall below 60º until October 2.  This map shows temperature anomalies (departure from normal), not actual temperatures; anomalies on the order of 10-15º below normal would put highs in the 70s to lower 80s, and lows in the 50s.  I will post a forecast for the timing of each front by Wednesday 9/7.

Preliminary Timing

  • Front #1: Saturday 9/10 … Front early…mainly 70s on Saturday. Highs in the 80s Sun/Mon
  • Front #2: Tuesday night 9/13 … Front late night or Wed morn. Highs: upper 70s – lower 80s by the middle of next week

Quick Stats for DFW*

  • Normal (average) high temperature for September 11-15:   90ºF
  • Last time we were below 70º: 3 months ago on June 6
  • On average, the first low temperature below 60ºF:  October 8

*Based on current 30-year average (1981-2010)

Computer model animation of the cooler airmass moving into the Southern Plains next week (9/12-19)

Computer model animation of the cooler airmass moving into the Southern Plains next week (9/12-19)


Third Update [Sunday 9/4]

Lauren here with a quick update. The beautiful weather continues today, and temperatures are in the upper 80s to around 90º. Highs by late afternoon in the lower 90s at most locations.

  • I expect a continuation of nice weather tomorrow, although an isolated shower is possible, mainly from DFW southward.
  • The upcoming week looks to be very warm, with temperatures in the 90s.
  • A cold front in about 9 days from now should bring an end to the 90s — at least for a while. Highs in the 70s to lower 80s, and lows in the 50s/60s are quite possible behind that front.
  • Enjoy your Labor Day tomorrow!

-Lauren


Second Update [Friday 9/2]

…19 Days Until Fall…
…Beautiful Labor Day Weekend in N. TX…
…Fall-Like Weather mid-Month…

There are no changes to the forecast that I posted a week ago. We will have a beautiful Labor Day weekend in N. TX, with seasonable temperatures. Highs around 90º Sat/Sun.

I still believe that a series of cold fronts mid-month (between the 12th and 19th) will bring fall-like temperatures to the Southern Plains and the Southeast. It is too early for specifics right now, but assuming the data remain consistent (as they have for the past 2 weeks), I should be able to post a forecast in a few days.

Countdown to fall: 19 days

-Chris R.


First Forecast [Saturday 8/27]

…25 days until fall…
…Possible cool-down by mid-September…
…Very nice Labor Day Weekend…

Summer has flown by and fall is my favorite time of year. For the past 10 days or so, I’ve seen remarkable consistency with long-range data which suggest that our first autumn cold front may plow through N. TX sometime between September 15 and 19. *IF* this comes to fruition, we would see our first nights with low temperatures in the 50s and highs in the 60s/70s.

I generally avoid making statements about anything beyond 7 days in advance, mainly because such forecasts are extremely time-consuming and require much more analyses than a glance at one model. However, I feel comfortable introducing the possible mid-September cold front, to give us some hope for real autumn temperatures, and to help us get into the pumpkin spirit

Labor Day Weekend in N. TX looks to be very nice, with highs in the 90s.

-Chris