Winter Storm Expected for North Texas Wednesday (3/4)

Final Update: Thursday 3/5 9 pm:  View the storm reports


Discussion #6 Wednesday 3/4 at noon: ***Winter  Storm Warning is in Effect***

I have been analyzing vertical thermodynamic profiles at various times over the next 15 hours and the evolution of the atmosphere continues to support a transition from rain to freezing rain this afternoon, then from freezing rain to sleet this evening. The atmosphere becomes cold enough at all levels aloft to support snow after 11 pm. Interestingly enough, some of the data suggest that the most significant precipitation may fall after the snow transition.  This winter storm is going to bring just about everything before it’s over with.  Keep in mind that all transition times will vary depending on your precise location, and it will be impossible to name off individual towns.  All of the transitions will occur from north to south.  For DFW specifically, this is an approximate timeline (Denton an hour or so earlier, Ennis an hour or so later… and the entire timeline is subject to a give/take margin of error):

  • 3 pm: Rain to freezing rain (up to .10” of frz rain by 8 pm)
  • 7-8 pm: Freezing to sleet (up to 1/2 inch of sleet)
  • Midnight: Sleet to snow (2 to 4 inches, locally higher)
  • Highest snow amounts appear to be Denton to Fort Worth eastward
  • Sleet will persist longer to the south of the metroplex.

Discussion #5 Tuesday 3/3 at 10:30 pm:

***Significant winter storm still expected for North Texas tomorrow afternoon through tomorrow night***
There are no changes to my forecast. I wouldn’t be surprised to see a Winter Storm Warning issued tomorrow morning (Wednesday 3/4). As for precipitation timing, I still believe everything will be just fine through noon (rain only). Temperatures will be falling through the 30s in the morning, and then below freezing by early afternoon. Shortly thereafter, conditions will begin to deteriorate. This storm appears to peak tomorrow evening, with convective elements (including thunderstorms) that could produce large amounts of sleet. To be honest, the convection (thunderstorms) is one of the aspects that really concerns me about this event (with temperatures in the 20s tomorrow evening). I believe that this will be a significant winter storm for North Texas. I will post updates tomorrow morning to keep you informed on the freezing line, the onset of the winter precipitation (afternoon), and other aspects of this rapidly developing winter storm.


Discussion # 4 Tuesday 3/3 at 2:55 pm:

1) I personally believe that a Winter Storm Watch is warranted, but that will be up to the good folks over at the NWS.

2) I still expect the Arctic front to move through N. TX tomorrow morning, around sunrise, with rapidly falling temperatures.

3) Forecasting the precise moment that the freezing line will move through every location will be an impossible task.  In general terms, the freezing line should be advancing southward through Gainesville/Denton by mid-morning, then into D/FW by late-morning/early afternoon (give/take).

4) I am still forecasting the front to arrive *sooner* than most of the numerical models have indicated based on a known tendency for this to occur.

5) Rain tomorrow will change to freezing rain and sleet tomorrow afternoon, increasing in coverage and intensity by tomorrow evening.

6) Mesoscale models continue to indicate convective instability which could lead to thunderstorms tomorrow evening.

7) Thunderstorms could produce rapid sleet/ice accumulations.

8) As of this moment, I believe the first part of the day will be just fine (rain only, through noon), with gradually deteriorating conditions in the afternoon (spreading from north to south with the freezing line).


Discussion #3 Tuesday 3/3 at 3:30 am:  ***Winter Weather Event Developing for North Texas***
As I’ve been discussing since last week, an Arctic front will move into North Texas Wednesday morning with falling temperatures during the day. I believe that the front will clear the DFW Metroplex by sunrise Wednesday, with temperatures falling below freezing during the morning. Once they fall below freezing, they will stay below freezing until Thursday. A series of upper-level disturbances (and mesoscale forcing mechanisms) will generate rain ahead of the front, and it appears that the forcing for precipitation will continue after the front passes.

There are signs of atmospheric instability Wednesday afternoon/evening, which may support convective elements, including thunderstorms. During that time, temperatures will be below freezing. Vertical thermodynamic profiles are supportive of freezing rain changing to sleet. Problematic accumulations are possible, and in fact, significant accumulations may occur.  As the atmosphere continues to cool Wednesday evening, there could be a changeover to snow before the precipitation ends (mainly from D/FW northward). On this map, I’ve indicated the predominant precipitation types during the time of maximum precipitation coverage. This map not take a changeover to snow into consideration. I will continue analyze all new data and closely monitor this developing situation. If trends continue, a Winter Storm Watch may eventually be issued by the NWS.

Strong Winds and Frigid Wind Chill Wednesday Afternoon/Evening

One aspect of this well-predicted Arctic front that will likely get push aside amid the upcoming discussion of accumulating winter precipitation is the strong wind and the resulting wind chill tomorrow afternoon/evening (Wed 3/4).  Here are some highlights:

  • Arctic front passes DFW by 9 am Wednesday
  • Temps falling to freezing by 1 pm (or sooner)
  • North winds increasing to 25-35 mph, Gusts to 40+ mph
  • Wind chills in the 10º to 15º range Wednesday afternoon/evening
  • Frost bite will be a concern for anyone outdoors
My Forecast for Predominant Precipitation Type

Predominant precipitation types expected Wednedsay (3/4) and Wednesday night


Forecast Discussion #2 (Monday 3/2 at 5:00 pm) 

No changes to the forecast discussion below (from yesterday, March 1). While there is a chance for winter precipitation on Wednesday, I use a personal “confidence threshold” of 30% before I formally mention it my forecasts (it reduces the “crying wolf” potential). In yesterday’s update, I mentioned that I see a number of mitigating factors arguing against a significant winter weather event. For the time being, I still see those and they are weighing heavily in my forecasts. I will have a brand new data suite this evening. I’ll definitely provide an update if I believe a significant winter weather event will occur.  Remember, this doesn’t mean that there will not be any winter precipitation.  However, my mission is to forecast for high-impact events.  I need to be confident, through a preponderance of all atmospheric data, that a significant winter weather event will occur.  Most of the current data suggest little more than a 2 or 3-hour overlap between the Arctic intrusion and the exiting precipitation Wednesday.

The Arctic front will move through between midnight and sunrise Wednesday, with temperatures falling below freezing during the morning.  This will be a quick-hitter, with a warming trend by the weekend (60s) and possibly near 70º by Monday.

Temperature Animation (Prepared Monday 3/2)

This is a rough animation depicting the progression of the Arctic front and the dramatic temperature changes behind it.  I believe the front will be moving a little faster than I’ve depicted here, such that DFW may be below 35º by sunrise Wednesday.

 


Forecast Discussion #1 (Sunday 3/1)

Posted: Sunday 3/1/15 at 5:00 pm: Following last week’s winter storms (sleet storm on 2/23/15 and snowfall on 2/27/15), a brief warming trend is underway, but I’m afraid the overcast will not be going anywhere. We should reach the mid 40s tomorrow (Monday), and even warmer for Tuesday. For the past week, some of the model data have consistently indicated temperatures warming to the lower 70s on Tuesday, but I really have a hard time believing that temperatures will be that warm. The airmass will continue to warm/modify, but with the wet/cold ground (evaporative cooling) and persistent overcast, I am inclined to undercut model guidance by at least 5 degrees on Tuesday — possibly even 10 degrees. I think a forecast high temperature on Tuesday in the lower 60s is reasonable for now. If it ends up being warmer, we’ll take it; and lower 60s will be a heatwave compared to the past few days.

Arctic Front Wednesday (3/4)

Another Arctic front will move through on Wednesday morning, but I still have uncertainty about the exact timing. Given the nature of Arctic fronts in the Southern Plains, I am inclined to forecast an earlier passage than later. Some of the data suggest that the front will move through around midnight Tuesday night, with temperatures falling into the 20s during the morning Wednesday (and staying below freezing all day). Other data suggest that the front will move through 12 hours later (early afternoon Wednesday), with temperatures falling as much as 30 degrees within the first 1-2 hours after frontal passage. I am leaning toward the first scenario: early passage, sometime between midnight and sunrise Wednesday. Wednesday’s “official” high temperature will likely occur at midnight, with temperatures falling from there.

Winter Precipitation Wednesday (3/4)

Upper-level disturbances will move across North Texas Tuesday night/Wednesday, and there is a possibility that we could see some winter precipitation on Wednesday. I am not 100% convinced about a widespread, significant winter weather event just yet, but there is still plenty of time to watch the data, monitor the upper-level disturbances over the North Pacific, and get a better handle on how they will evolve/interact with the Arctic airmass.

Yes, some of the model data have been quite aggressive for the past few days with solutions depicting a winter storm over North Texas midweek; but I do see some mitigating factors that argue against this scenario.

I will update with future data. This promises to be a busy week in N. TX.