Category Archives: Forecast Blog

ANOTHER 100 DEGREE DAY AT DFW AIRPORT – FALL COOLDOWN ON THE HORIZON?

Yesterday, the mercury hit 100°F at DFW Airport on southwesterly winds. I really thought we would get through the rest of our hot season without hitting triple digits one more time, as that wasn’t readily apparent in the overall synoptic pattern. Today, the winds should be more southerly/southeasterly, H5 heights a little lower, and H85 temps a degree cooler as a result. This may help to keep temperatures below 100°F today, especially with the 0.35 inches of rain received yesterday at the airport, but it will again be close. Heights over all should continue to weaken as we head through the rest of the week. Moisture will begin to advect northward on Thursday, thus after another hot day on Wednesday, temperatures should be slowly coming down.

The guidance (both the GFS and ECMWF) are coming into better agreement with the pattern for next week with more rain opportunities beginning as early as this weekend. Both show the first significant cold front of the autumn season next week, but with slight timing differences. This is something I have been watching since the cool down earlier in the month didn’t pan out, and I suspected that our next big shot at cooler air may come the last week of September. The ECMWF weeklies have been locked on to this for a while now. This will be something I will have more details on through the week as better data become available. It should be noted that if the current guidance holds, it will be significantly cooler to close out the month of September.

SIGNIFICANT SEVERE WEATHER EVENT UNFOLDING FOR THIS AFTERNOON

Residents of North Texas, and in particular, residents in the forecast range of this website should be paying attention to the weather this Friday, April 29th afternoon. An extremely unstable atmosphere has setup shop across the area with excessive CAPE values of 3000 to 4000 J/Kg. A warm front has moved north of the area near a Bowie-McKinney line and has become stationary with a dryline extending southwest back toward Abilene. A surface low/triple point was noted between Snyder to Seymore. This dryline is expected to push eastward in response to height falls across the southern Plains. Showers and thunderstorms will begin firing along this dryline this afternoon and will very rapidly become severe. Initially these storms will be discrete supercells and be capable of producing all modes of severe weather including tornadoes. The convection will congeal into a squall line as the event progresses and march eastward away from the area by evening. The following hazards will be possible with this event:

Very large hail to the size of softballs
Damaging straight-line winds
Flooding
Frequent lightning
Tornadoes

A Tornado Watch will likely be issued shortly. Residents of North Texas should keep advised of the latest weather watches and/or warnings and be prepared to take action.

HEAVY RAIN RETURNS AS SPRING THUNDERSTORMS FIRE FOR THE FIRST TIME

The coming week is going to be a wet one for much of North Texas, including the DFW Metroplex. A very big upper-level low will be sinking south into Mexico and then ejecting east northeast slowly. The slow movement of this system will allow abundant moisture to stream into the region ahead of it. This is already noted with overnight low temperatures well above normal for this time of year.

Showers and thunderstorms will begin to fire tomorrow along a dryline in West Texas. At the same time a jet streak will be out across the Texas and Oklahoma panhandles juxtaposing North Texas in the right entrance quadrant of a speed max which will enhance lift across the area. Some hi-res models are forecasting convective development tomorrow as far east as the I-35 corridor. All storms that form should be supercellular in nature and elevated. With 1500 to 1800 J/Kg of convective potential energy, or CAPE, available, some of these storms could be strong to severe. Large hail would be the primary threats. In addition to the severe threat, heavy rainfall will also be possible as precipitable water values, or pWATS, climb above the 99th percentile for March. This could greatly enhance rainfall rates.

Monday night into Tuesday morning models are showing an MCS (mesoscale convective system) moving across North Texas with the potential for very heavy rainfall. The outflow boundaries from this system could act as foci for additional storm development on Tuesday as widespread lift begins to encroach on the area as the upper-level low begins moving east northeast. The MCS could also serve to help stabilize the atmosphere on Tuesday which would help alleviate the severe weather threat. While it is too early to pinpoint the mesoscale environment on Tuesday, it does appear all modes of severe weather will be possible on Tuesday, including tornadoes. A dryline will sharpen west of the Metroplex and act as focus for storm development as jet streak lifts out of the lower Rio Grande Valley. In addition to the severe weather threat, heavy rainfall will also be likely given the high pWATS. It is possible that Tuesday could see the daily rain record broken.

A weak cold front will push through ending the severe weather potential, but not the rain. Overrunning showers will likely continue. The remainder of the week looks to remain wet through Friday as north and central Texas remain on the eastern flank of the upper-level low. There won’t be significant drying until the upper-low moves far enough east by the weekend to end all rain.

FIRST SIGNIFICANT CHANCE FOR RAIN IN A WHILE AT DFW

It is looking like our first significant chances for rainfall at DFW will materialize by Sunday into Tuesday as a cold front and upper-disturbance approaches the region. Until then, we must contend with strong ridging over our area with gusty southerly winds. Combined with dried fuels, low humidity, and near record warmth, these strong winds will present elevated fire weather concerns, especially west of the I-35 corridor where Red Flag Warnings have been issued. The strong winds today will gust to near 40 mph at times, as a result, the National Weather Service in Fort Worth has issued a Wind Advisory for all of our forecast area. Temperatures will warm some 15 to 20 degrees above seasonal normal values with highs approaching or exceeding 80°F today and tomorrow. Overnight lows tonight will be near our normal high temperature for this time of year, struggling to get below 60°F, if at all.

The ridging should begin to relax on Saturday transitioning to more zonal flow aloft. This will allow the trough and cold front across the Central Plains to begin slowly sagging southward. This front will move across our area rather slowly beginning on Sunday. As it does, a disturbance will move across enhancing lift across our area which will enable showers and thunderstorms to fire. The best chance of rain will be along and behind the front as it moves through Sunday night into Monday. The highest moisture will be along and east of the I-35 corridor, thus this is where the best chances reside for receiving the most rainfall with this system. It is too early to say with confidence exact amounts, but we could be looking at widespread 1 inch plus amounts along and east of the I-35 corridor, especially with PWATs expected to climb as high as 1.50 inches.

SNOW NEXT WEEK? MAYBE NOT SO MUCH [UPDATED]

UPDATE: There continues to be no additional data that there will be snow or any wintry precipitation on Monday. There has been a lot of hype that there was going to be a snow or winter weather event on Monday for the DFW area. We are getting a shot at some modified polar air tomorrow, but the latest data suggests that this air mass will not be all that cold. In fact, DFW may struggle to get below the 30°F mark, yet again, on Sunday and Monday mornings. It is true that a very weak disturbance will traverse the area on Monday, but the lower 2000 feet of the atmosphere looks to be at or above freezing. This disturbance will have very little moisture to work with and have to overcome a very deep layer of dry air above. Thus, any precipitation would likely evaporate or sublimate before reaching the ground. This is a phenomenon we refer to as virga. The upper air pattern is not one that is favorable for significant moisture return or setup for a big winter weather event for DFW. We continue to see no indication of a major intrusion of Arctic air or wintry precipitation within the next 10 days. El Niño winters tend to prevent deep intrusions of Arctic air very far south, and in this particular winter, source regions are not all that cold. Thus, rather mild low temperatures (for this time of year) look to continue for several days. This means it will be hard enough to get us to freezing, much less cold enough for any significant wintry precipitation to cause problems.

For starters, a couple of short wave troughs will be moving across the area today and tonight which will be our next rain maker. The second trough is the stronger of the two, and that will be our best chance at seeing rain. This will not be a big thunderstorm or severe weather event. The atmosphere is too stable for big thunderstorms, though a clap of thunder or lightning strike cannot be entirely ruled out. There will be some drizzle and light rain today that will increase to a light to moderate rain later this afternoon into tonight as the stronger disturbance spreads lift across the area. Most locations will likely see some rain from this, but the heaviest rainfall will be east of the I-35 corridor. Rainfall amounts should generally stay around an inch or less with the heavier amounts further east.

Rain chances will end by tomorrow morning rapidly from west to east as the shortwave troughs move off to the east. Tomorrow will be sunny and much warmer with temperatures rising well above normal into the upper 60s. A repeat performance again on Friday, but a strong Canadian/modified Arctic airmass will be surging southward on Friday.

This front will move through the area early Saturday morning bringing much colder air to the region. It is likely that both Sunday and Monday morning lows will be below freezing area wide. Just how cold the temperatures drop will depend on cloud cover. Right now it looks as though our first dip below 30°F will be possible by Monday morning at DFW Airport. DFW has yet to do so this winter season, and a new record will be set to be the latest in the winter season to fall below 30°F. The previous record was January 8, 1932 (29°F).

At the same time, several models are bringing a weak disturbance across the area and producing snow on Monday. There have been widespread rumors across social media from various sources that this could be a big snow event. Well, there are several problems with this setup. One, it is not a favorable pattern for bringing moisture to our area, thus the weak disturbance will be moisture starved. Second, the disturbance is weak and not very strong. The upper air pattern is not one that has historically brought substantial snowfall to our area. Then, there is the question of how cold it actually will be when there is precipitation as nearly all models warm us above freezing on Monday. At this time, it is still possible that some flurries or light snow can fall on Monday with the passage of the disturbance, but there is nothing in the data to suggest more than that. This certainly does not look like a major winter storm at this time. While it is possible to snow, the chances are very low that precipitation can form in the dry air and that it will be cold enough to support wintry precipitation. For these reasons, we are not forecasting snow at this time. This may change with future data, but right now the forecast will remain dry and chilly for next Monday.

DFW 2015 YEAR IN REVIEW

2015 was the 19th hottest year on record for DFW with an average temperature of 67.2°F. December 2015 was the second hottest on record behind 1933 for the area with an average mean temperature of 53.6°F. It was the wettest year in all of DFW weather recorded history with an incredible 62.61 inches of rainfall. May 2015 was the wettest May ever recorded for the area with a whopping 16.96 inches of rainfall. Thanksgiving 2015 was the second wettest Thanksgiving of record with 2.71 inches of rainfall. The highest temperature for the year was 106°F on August 9th and 10th. The lowest temperature for the year was 16°F on January 8th.

SOME SNOW WILL BE POSSIBLE TONIGHT INTO TOMORROW ACROSS THE FORECAST AREA

As our much advertised vigorous upper-level storm system moves across the area this evening, rain will become mixed with sleet and snow from west to east in the areas depicted in the map below. The highest accumulations are expected mostly outside our extreme western counties where 1 to 3 inches are possible and a Winter Weather Advisory has already been hoisted by the National Weather Service office in Fort Worth. A dusting to under an inch will be possible in our northwestern counties. Closer in to the heart of our forecast area, wet snow flakes will be mixing in with the rain with a brief window for a transition to all snow early tomorrow morning before precipitation shuts off. However, temperatures will be at or above freezing and coupled with recent warm grounds, we expect little to no accumulations in these areas.

Snow will begin mixing with sleet and rain this evening across the areas shaded above. This graphic shows where we expect accumulations.

SEVERE WEATHER THREAT TODAY AND TONIGHT

As discussed, a powerful storm system will be affecting the area for the next couple of days. This storm system will be responsible for a variety of weather across the state, including a historic blizzard in West Texas to heavy rainfall and severe weather in our area. The Storm Prediction Center has placed our entire forecast area in an enhanced risk area for severe weather. Abundant moisture, indicative of dewpoints well into the 60s, very warm temperatures well into the 70s, will create convective instability around 2000 J/Kg. Combined with adequate shear, approaching cold front, and destabilization from storm system, the parameters are in place for severe weather across our area. The main threats will likely be heavy rainfall, but damaging winds and large hail will also be possible. In any discrete storms that can become rooted in the boundary layer may be able to spin up an isolated tornado. Most of the convection will be tied to a strong Arctic cold front that will move across the area and force the convection to take on a linear storm mode which should lessen the tornado threat. The cold front should be around DFW in the 10:00 PM to 12:00 AM timeframe. Behind this front much colder air will spread into the region lessening the severe weather threat.

Severe weather threat for December 26, 2015 as issued by the Storm Prediction Center.

CURRENT WATCHES AND WARNINGS ACROSS THE REGION

Current watches/warnings across the state as of 10:00 AM December 26, 2015.

Persons traveling across the Lone Star State should be aware of all the different watches and warnings posted as a powerful winter storm impacts the region. Residents of North Texas should be aware that the Winter Storm Watch has been expanded to just outside this website’s forecast area border. Accumulating snowfall will be possible in this area Sunday night. Wet snowflakes may fall as far east as the DFW Metroplex, though confidence in this is not high and highly depends on the track of the upper-level low and what dry slotting develops. Anyone traveling to West Texas should note that traveling in this region is strongly discouraged as a historical blizzard is going to take shape.

HEAVY RAIN EXPECTED TOMORROW INTO SUNDAY

As discussed yesterday, we are still expecting a heavy rain event to affect the area beginning tonight and lasting into Sunday. A Flash Flood Watch has already been issued for the entire forecast area by the National Weather Service office in Fort Worth. The graphic below depicts what we can expect in terms of rain amounts by the end of this event. On average, 3 to 6 inches of rain is expected across our area with locally higher amounts possible. This will only exacerbate the extraordinary rainfall received this year and flooding and flash flooding will be of major concern.

Post Christmas 2015 heavy rain event. Map depicts expected rain totals by the end of the event.