Severe Weather Threat Saturday

FORECAST DISCUSSION:
As a potent upper level low pressure system moves across central Texas on Saturday showers and thunderstorms will become likely. Some of the storms that develop will become strong and/or severe with hail, damaging winds, and even the possibility for a few isolated tornadoes. The Storm Prediction Center (SPC) has placed all of central Texas under the SLIGHT RISK category for severe weather on Saturday. What this means is that any one location in central Texas has a 15% chance of seeing severe weather. Along with the threat for severe weather, there is the potential to see a widespread 1-2 inches of rain across the area with highest totals expected to be found along and east of the Interstate 35 corridor.

SLIGHT RISK=YELLOW SHADED AREA:

As the upper level storm system approaches Texas from the west, it causes air to converge, rise, and diverge aloft. Warm, humid air at the surface is forced to rise into significantly colder air aloft allowing for thunderstorms to develop. In the northern hemisphere, areas of low pressure spin counter-clockwise. At the surface, this upper level storm system will be pushing a Pacific Frontal Boundary across the state. Ahead of this frontal boundary is where the showers and thunderstorms will form. Once the front clears the area by late Saturday evening, the storm threat will diminish and skies will clear from west to east as much drier and more stable Continental air mass (air that originates over the desert southwest and the deserts of northern Mexico) moves into the area. West southwesterly winds on Sunday will allow for highs to climb into the mid to upper 70s area wide under a mainly sunny sky. 

Storm System as seen on Water Vapor Imagery (Red L=storm's location Friday evening): 

Water Vapor Imagery Loop: Can you spot the counter-clockwise rotation south of Arizona? That's the upper level low!!

FORECAST RADAR IMAGERY (NAM 4 KM HI-RES MODEL):

***WAVES OF STRONG/SEVERE STORMS DURING THE DAY SATURDAY WILL BE FOLLOWED BY A LINE OF STRONG/SEVERE STORMS DURING THE EVENING HOURS AS THE PACIFIC FRONT CROSSES THE AREA FROM WEST TO EAST***

(Loop starts at 9 a.m. Saturday and runs through Sunday Midnight)

***PLEASE STAY WEATHER AWARE DURING THE DAY ON SATURDAY AND KEEP AN EYE TO THE SKY*** 

WEATHER TIMELINE: 

Friday Night: Increasing chances for showers and thunderstorms as upper level low continues to move closer to Texas; a few strong storms are not out of the question with the main threats from those storms being heavy rain, lightning, and gusty winds. Mild with lows in the 60s with a south wind; 60% chance of rain

Saturday: Thunderstorms likely; some of the storms that develop will become severe with large hail, damaging winds, and possibly an isolated tornado or two...we are likely to see several rounds of storms during the day. Highs will be in the lower 70s; 100% chance of rain

Saturday Night: Pacific Front moves through the area during the late evening hours putting an end to storm chances; skies clear overnight from west to east as drier air moves into the region. Cooler with lows in the 50s

Sunday: Sunny, breezy and warm with highs in the mid to upper 70s! Enjoy!

Sunday Night: Cold Front moves through the area dropping lows into the 40s under a mostly clear sky

Monday-Friday of next week: Sunny/clear with highs in the 60s and lows in the 30s and 40s...beautiful fall weather! Enjoy!

SEVEN DAY FORECAST:

Early Season Arctic Blast Next Week!

TGIF everybody! There is a lot to talk about in the weather department so let's get right to it. The rain that we saw over the last several days was a very welcome sight and overall a beneficial rain for central Texas. Unfortunately, it is going to take a lot more rainfall events like that to fill up the Highland Lakes. Everybody in central Texas picked up over an inch of rain with several locations receiving 2-4 inches of rain. 

A really cool way to check out rainfall totals from the area is through the LCRA's Hydromet Network. Use the menu on the left-hand side of the website to display lots of different data from across the region, including temperature, rainfall, humidity, and lots more. Click HERE to access the website. It works just like any other Google Map application so feel free to zoom way down to your neighborhood. 

NEXT WEEK'S ARCTIC BLAST:

Would you believe it if I told you the Arctic Air getting ready to be unleashed on the central and eastern U.S. next week can actually be attributed to what was once Super Typhoon Nuri, the equivalent of a category 5 hurricane that moved through the western Pacific earlier this week, just east of Japan. As Nuri continues to move farther north into colder waters of the northern Pacific it has transitioned from being a warm-core low pressure system to a cold-core low pressure system, basically Nuri has lost its tropical characteristics. Meteorologists refer to a tropical cyclone that loses its tropical characteristics as an extra-tropical cyclone. As extra-tropical cyclone Nuri crosses the northern Pacific it is forecast to greatly strengthen thanks to a strong jet stream and is likely to go down in history as one of the most powerful low pressure systems to every develop in the Pacific and it has its eye set on Alaska. Weather historian, Christopher C. Burt, says the all-time low pressure record for Alaska is 926 mb set back at Dutch Harbor on October 25, 1977. Extra-tropical Nuri has a good chance of beating that record if its center passed over the Aleutian Islands of Alaska on Saturday morning. Hurricane force winds and very rough seas, with waves as high as 45-50 feet possible across Alaska's Aleutian Islands.

Super Typhoon Nuri earlier this week (South of Japan): Photo was taken November 4th

Okay, so how is this going to affect us here in Texas. Well, this unusually strong area of low pressure will amplify a ridge of high pressure over the eastern Pacific and across the west coast of the United States to build way into the Alaska, the Arctic Circle and northwestern Canada. As that ridge of high pressure amplifies it will allow for a trough of low pressure to deepen to its east across central Canada and the lower 48...this unusually strong ridge of high pressure to the west and strong trough over much of the U.S. will help to pull very cold Arctic air from the Arctic Circle and even Siberia down into the central and eastern U.S. early next week.

Weather Set-Up (Described in paragraph above):

FRONT'S ARRIVAL/DAY BY DAY FORECAST

The much anticipated cold front will arrive in central Texas early Tuesday morning (Veteran's Day Morning). Ahead of the front on Monday, southwesterly surface winds will push highs well into the 70s across the area.

MONDAY: Mostly sunny, mild, and breezy with highs in the mid to upper 70s; SSW wind 10-20 mph

TUESDAY: Arctic Front pushes through central Texas between midnight to 7 a.m. The front will likely sweep through the area dry as moisture levels across the area will not be sufficient to produce rain...strong northerly winds develop quickly behind the front keeping temperatures in the 50s all day on Tuesday under a mostly sunny sky...north winds will be kicking 15-25 mph with gusts over 30-35 mph likely.

GFS Model Showing Front arriving early Tuesday Morning:

TUESDAY NIGHT: Clear, cold and gusty with temperatures dropping into upper 30s to lower 40s across the area

WEDNESDAY: COLD morning with temperatures in the upper 30s and lower 40s (wind chills in the lower 30s). Highs will struggle to reach the lower 50s across the area with some locations not getting out of the 40s under a mostly sunny sky.

WEDNESDAY NIGHT: Lows drop into the 30s area wide (a few locations across the western and northern Hill Country may receive a light freeze) Temps: 34-39°F

GFS Forecast Lows Wednesday Night: 

THURSDAY: Sunny and chilly with highs in the upper 40s to lower 50s

THURSDAY NIGHT: Lows drop back into the 30s; low-lying spots may get a light freeze

Thursday Night Forecast Lows: 

Warming trend takes highs back into the upper 50s to lower 60s next weekend. Long range models indicate a second blast of Arctic Air possible by the beginning of the week after next, but I'll have to continue to watch for model consistency.