Forecast Discussion:
Good Monday evening everybody. I hope you all had a fantastic weekend. After a chilly, cloudy weekend southwesterly surface winds today in response to an approaching cold front and upper level disturbance allowed for temperatures to soar into the upper 60s and 70s across south central Texas today. We officially topped out at 77°F this afternoon at Camp Mabry (that's 15 degrees above the "normal" high of 62°F for this time of year).
A strong and deepening trough of low pressure across the center of the country will continue to build south into Texas tonight and into Tuesday. This deepening trough of low pressure will push a strong cold front and upper level disturbance across the area overnight tonight into Tuesday morning. This disturbance will be riding the outer periphery of the trough of low pressure (see image below).
Current Location of the Disturbance:
Big Red "L" over Nebraska and South Dakota represents position of large upper level low...Red "Circle" indicates current position of upper level disturbance set to move through central Texas late tonight into Tuesday Morning...Red "arrows" represent the steering winds (Jet Stream)...the big trough over the middle of the country is clearly visible. The disturbance is currently producing light rain and snow across northeastern New Mexico and portions of the Texas Panhandle
As the disturbance crosses the area overnight tonight into Tuesday, showers and a rumble of thunder will be possible; highest rainfall chances will come for northern portions of south central Texas from the Austin Metro Area and points north all the way up into the Dallas/Fort Worth Metroplex and southern Oklahoma. Disturbance will be moving fast and rain that falls should be light. Given those two factors, rainfall accumulation will be very light (<0.15 inches). It wouldn't surprise me if we don't get more than a few sprinkles or very light showers around Austin Tuesday morning.
Forecast Radar (8 a.m. Tuesday Morning)
Greatest energy with this disturbance looks to pass just north of south central Texas according to the latest high resolution NAM Model...Williamson County north to Dallas appear to have the best shot at seeing rain, of course if this system decides to track a bit farther south, rain chances would increase for us here in south central Texas
Forecast Accumulated Rainfall
Again, best rainfall chances look to move just north of the area...that's where the higher rainfall accumulations are likely to occur
In addition to the chance for rain across the area, MUCH COLDER weather will move in behind a strong early-morning cold front. Highs tomorrow (Tuesday) will actually occur after midnight ahead of the cold front. Cold front will arrive in the Hill Country first between 5-8 a.m. Tuesday morning. The front will then blow into the Austin Metro Area between 8-10 a.m. and should push through the remainder of eastern portions of central Texas between 10-11 a.m. Tuesday morning. Winds will be quite gusty behind the front sustained between 10-20 mph out of the north northwest with gusts between 25-30 mph likely. Our highs on Tuesday will be in the upper 50s (just after midnight) and drop into the 40s and lower 50s for the remainder of the day Tuesday behind the front. Breezy north winds and mostly cloudy skies will make it feel even colder. Especially since we saw temperatures in the 70s today. Clouds clear from northwest to southeast across the area late Tuesday into early Wednesday as the disturbance/cold front push east of the area. Areas of the Gulf Coast/Deep South may get some severe weather out of this system Tuesday afternoon/early Wednesday morning. The Storm Prediction Center has highlighted those areas in the map below.
Forecast position of Front 9 a.m. Tuesday Morning
Front will be pushing into the I-35 corridor (windy & much colder conditions can be expected behind front)
Tuesday Severe Weather Outlook
Areas shaded in YELLOW have a 15% chance of seeing severe weather (Hail 1" in diameter or greater and/or winds of 58 mph or greater and/or a tornado)
Christmas Eve Forecast: Chilly start to the day with temperatures in the 30s area wide will give way to a SUNNY, BREEZY, AND CHILLY afternoon with highs only topping out in the upper 40s to lower 50s (48-53°F range)...a breezy north wind will ensure a brisk, chilly day for all of south central Texas. Temperatures Christmas Eve into early Christmas Morning will bottom out in the 28-34°F range. A freeze is likely for all low-lying and out-lying areas. The urban heat island effect will should keep the center of Austin a degree or two above freezing, however, low-lying spots within the city limits should prepare for a light freeze.
Christmas Morning Forecast Lows
***IF WINDS REMAIN BREEZY DURING THE OVERNIGHT HOURS MORE LOCATIONS WILL REMAIN SAFELY ABOVE THE FREEZING MARK, HOWEVER, IT WILL STILL BE COLD WITH TEMPS IN THE 30s***
Christmas Day and after: COLD morning will give way to a sunny, cool and breezy afternoon with highs in the upper 50s to lower 60s across the area. Southerly winds will be blowing 10-15 mph with higher gusts. Southerly winds will keep temperatures well above freezing across the area Christmas Night into Friday morning in the 40s. Don't get me wrong, it will still be quite chilly with those breezy southerly winds.
Sunny and pleasant on Friday after Christmas with highs in the mid to upper 60s area wide on southerly winds ahead of a late evening cold front that will blow through and cool us off for the weekend with highs dipping back down into the 50s for Saturday and Sunday. There is a slight chance for some showers late Friday into early Saturday with the front. A freeze is possible for low-lying out-lying locations Saturday night.
Arctic Blast Possible Before New Year's
Long-range forecast models continue to indicate a significant change in the weather pattern as we head into the days before New Year's Eve. A strong ridge of high pressure is still forecast to develop across Alaska and northwest Canada. That ridge works to deepen low pressure to east and send lots of frigid, Arctic Air south into the lower 48. The long-range GFS Model shows temperatures running some 15-30 degrees COLDER THAN NORMAL for late December. New Year's Eve and New Year's Day have the potential to be pretty cold across central Texas with hard freezes possible. Still way too early to know for sure, but all forecast models continue to hint and indicate that we are in for some significantly colder weather to end the month of December and ring in the new year. Not just here in Texas, but across a good chunk of the central and eastern United States.
Forecast Temperatures for Midnight New Year's Day 2015-BRRR!!!
GFS Model forecasting a large swath of 15-30 degree below normal temperatures in the middle of the country later this month
Big Ridge (Red/Magenta Blob) forecast to develop over northwestern Canada/Alaska...that will send frigid air south into the lower 48
***Please understand that this blog post is just a forecast and is subject to change***
Weather Discussion:
With Christmas right around the corner, everybody wants to know what the weather is going to be like. To be honest, there are a lot of ups and downs over the next seven to ten days. As it looks right now, we have three separate cold fronts lined up to move through Texas between now and the end of the month. Each front looks to be progressively stronger.
We have been trapped under the clouds here along the I-35 corridor for the past several days now, however, portions of the Hill Country managed to see some this afternoon (check out the Visible Satellite Imagery from earlier today below). Clouds will hang on tough again tonight, but SHOULD slowly begin to break up and allow for some sun breaks by Sunday afternoon. A returning southerly wind flow and some afternoon sun will help highs temperatures climb 5-7°F across the area for Sunday after a chilly start to the day in the 40s. Highs Sunday afternoon will range from the upper 50s in the coolest locations to the lower 60s in the warmest spots. No rain is expected on Sunday, however, if clouds decide to remain stubborn highs will only make the upper 50s across central Texas.
Saturday Afternoon Visible Satellite Image of Texas:
(Monochrome view of Texas from space this afternoon, yellow lines overlaid on top of the satellite image represent state and county outlines)
As a strong and deep trough of low pressure builds down into Texas on Monday a surface area of lower pressure is expected to develop across north Texas. In response to the counter-clockwise wind flow around that area of surface low pressure our winds across central Texas will be out of the south southwest on Monday. The southwesterly component to the wind on Monday combined with strong southwesterly winds blowing around 4-5,000 feet above us will ensure a warmer day across south central Texas with highs climbing into the low to mid 70s under what should be a mainly sunny sky. If some stubborn low clouds were to stick around along and east of I-35, highs may only make the upper 60s. I mention this because a few of the latest forecast models want to keep some stubborn low-clouds around the area Monday.
Forecast Highs Monday (Snapshot of the NAM 4 KM High Resolution Model):
I've circled where the model believes low clouds could hang tough
The same deep trough of low pressure that will bring us the spring-like conditions on Monday afternoon will kick the surface low in north Texas to the east by early Tuesday morning. As that surface low is forced east by a strong disturbance riding the jet stream (river of fast-moving air) around the outer fringes of the trough, the door will open for a strong cold front to push through south central Texas Tuesday morning. A spotty light shower or two possible with the front as it crosses eastern portions of south central Texas, however, the majority, if not all of central Texas will remain dry. Strong northerly winds behind the front on Tuesday morning will knock highs into the 50s Tuesday afternoon under what should be a mostly sunny sky. North northwest winds sustained between 15-20 mph gusting to 30 mph will ensure a brisk feel to the day on Tuesday. Lows Tuesday night will drop into the 30s area wide. We will wake up to temperatures in the mid 30s right in Austin Wednesday (Christmas Eve morning). Areas north and northwest of Austin may receive a light freeze, however, a brisk north wind will not allow for a hard freeze.
Here's a look at what the GFS Forecast Model believes that trough of low pressure will look like on Tuesday over the center of the country...this map is for 500 mb (18,500 feet above sea level) The 500 mb level is extremely important in determining where weather systems (mid and upper level highs and lows) are headed: Can you spot the ridges and troughs?
Deep South Severe Weather Threat: Ahead of that strong, deep trough of low pressure that will be over Texas on Tuesday, severe weather is possible for areas along the Gulf Coast and Deep South from Louisiana to Florida. The Storm Prediction Center is monitoring all areas shaded in yellow on the map below for the possibility of severe weather on Tuesday (December 23). For a fantastic, detailed look at the possibility of severe weather for the Deep South on Tuesday, click HERE.
Storm Prediction Center Severe Weather Risk Area for Tuesday, December 23, 2014:
Stay up to date with the latest severe weather outlooks HERE.
Mostly sunny and pleasant on Christmas Eve after a cold start to the day with highs rebounding into the upper 50s to lower 60s...clear and chilly during the evening hours with temperatures quickly dropping into the 40s to lower 50s after sunset. Lows drop into the 30s to lower 40s area wide by Christmas morning. A returning southerly wind Wednesday night will help to keep the area above freezing. However, it is not out of the question for the lowest-lying locations across the area to receive a very light freeze. Sunny, beautiful and breezy on Christmas Day with highs in to the mid to upper 60s. Highs in the upper 60s to near 70°F for the Friday after Christmas ahead of our second cold front that is set to move through the region late Friday evening. As it looks right now, highs next weekend look to be quite chilly in the 50s with lows in the 30s. A fairly widespread freeze is possible across south central Texas next Saturday night/Sunday morning.
Looking towards the end of the month and into the new year, long range models continue to indicate a transition to MUCH COLDER weather across a good chunk of the lower 48. In their 8-14 day outlook, the Climate Prediction Center is indicating below normal temperatures for much of the lower 48 between December 26-January 3, 2015. Of course, this is a long range forecast and things are likely to change between now and then, overall it looks to be turning significantly colder for a good portion of the U.S. (including Texas) late this month into the new year.
Climate Prediction Center 8-14 Day Temperature Outlook:
Click HERE to go to their website
A big ridge of high pressure is forecast to build across Alaska and northwestern Canada late this month...that ridge of high pressure helps to dislodge cold, Arctic Air and push it south into the lower 48. Big bulls eye of red and magenta over Alaska and northwestern Canada represents that big ridge of high pressure. That ridge of high pressure helps to deepen low pressure to the east of it and that dip in the jet stream is what pulls that frigid air south. Pretty cool, huh? Once that cold, dense air mass is tapped it is hard to stop it from pouring south into the lower 48...I like to think of those cold Canadian, and especially arctic air masses as bowling balls.
Weather Discussion:
We officially topped out at 74ºF this afternoon at both Camp Mabry and Austin Bergstrom International Airport. A much cooler air mass is settling into the region tonight and will set us up for a MUCH COOLER Tuesday and Wednesday. Lows will dip into the 40s across most areas tonight with some mid to upper 30s likely across the Hill Country. A chilly start to the day on Tuesday will give way to a mostly sunny and cool afternoon with highs in the upper 50s and lower 60s area wide. Clouds will be on the increase in a hurry from the west and southwest Tuesday afternoon and evening ahead of a quickly approaching trough of low pressure (elongated area of lower atmospheric pressure) currently affecting California and the desert southwest.
The Big Red L represents the trough (TROF) of low pressure and the red arrow depicts its forecast track: For a really cool loop of this map in motion click HERE. This map depicts water vapor which basically shows mid and high level moisture in the atmosphere. The green lines are isobars (lines of equal atmospheric pressure) and are drawn on to help find areas of high and low pressure around 18,500 feet above the earth's surface.
Rain is a good bet on Wednesday as warm, moist air rides over the cooler air here at the surface thanks to the approaching trough. Get ready for a dreary, chilly and showery day on Wednesday with temperatures likely to stay in the 40s and 50s all day. Rain on Wednesday will be light to moderate in intensity. This is not the right weather set-up for big storms or heavy rainfall. Dense fog may become an issue late Wednesday into Thursday morning as much warmer air from the south advects north into central Texas. That warmer air will push highs back into the lower 60s ahead of another area of low pressure that will push across Texas from west to east Thursday and Friday. Good chance for showers on Thursday with some heavier showers and possible thundershowers Thursday night into early Friday morning ahead of a cold front that will usher in more chilly air into the area from the northwest and clear out our skies on Friday afternoon. Highs hover into the 50s to near 60ºF Saturday through Monday of next week with lows in the upper 30s and 40s. More light rain possible early next week with another weather system from the west. Latest model guidance showing a mild Christmas Eve and Christmas Day with highs in the 60s, possibly low 70s ahead of a strong cold front that would push through the region late Christmas Day into the day after Christmas. (Please keep in mind this is a very early look at the Christmas forecast. Weather has a mind of its own and this is only one model's take on what is going to happen).
Here's a look at Forecast Simulated Radar Reflectivity for 3 P.M. Wednesday afternoon:
Latest forecast guidance is forecasting 1/2 to 1 inch of rain to fall across a good portion of central Texas between Wednesday morning and Friday afternoon. Keep your fingers crossed that these forecasts verify. We can use every drop we can get here in central Texas. No freezes likely between now and Christmas Eve...that may not be the case for the days after Christmas if latest model data verifies. The Weather Prediction Center is forecasting a good 1-2 inches of rainfall falling across a good chunk of central Texas over the next 5 days (see image below):
Upper level storm system currently affecting the west coast of the United States will continue to push east over the weekend and affect us here in Texas by Sunday. Warm and mild weekend in store with highs in the lower to middle 70s and lows in the upper 50s to near 60°F. Southerly winds will begin to pick up across the area Saturday afternoon and will be rather breezy on Sunday ahead of the storm system moving into the state. Spotty sprinkles or a very light rain shower are possible Sunday morning. Highs Sunday afternoon will make the lower 70s ahead of a Pacific Cold Front that will work its way through the area from west to east during the afternoon and evening hours. The warm, moist air out ahead of the front will be forced to rise in turn giving us a 50% chance for showers and thunderstorms on Sunday afternoon/evening, possibly lingering into the early morning hours on Monday depending on how quick this weather system pushes through the area. Some of the storms that develop on Sunday will have the potential to become strong with heavy rain and deadly cloud to ground lightning. The severe weather threat on Sunday is not zero, however, it is not very likely. With that mentioned, the Storm Prediction Center has placed a large swath of the central United States from Kansas south into central Texas under the MARGINAL RISK category for severe weather. What this means is that there is a 5% chance that any location in central Texas from Austin north will see severe weather. A thunderstorm is defined as severe when it produces hail quarter size (1 inch in diameter) and larger, and/or winds of 58 mph or greater, and/or a tornado.
STORM PREDICTION CENTER MARGINAL RISK AREA FOR SUNDAY:
Click HERE to go the Storm Prediction Center's Website
Quick refresher on watches/warnings issued by the National Weather Service and Storm Prediction Center as defined by the National Weather Service:
WEATHER WATCH: atmospheric conditions are FAVORABLE for the type of weather specified (generally issued for a larger geographic area for a longer time span; 4-6 potentially up to 24 to 48 hours)
WEATHER WARNING: the type of weather specified is IMMINENT/OCCURRING and is and an immediate threat to life and/or property (smaller geographic area; shorter time span of 1/2 to 1 hour)...proper action should be taken to protect life and/or property.
FORECAST RADAR FOR SUNDAY EVENING (NAM FORECAST MODEL):
Model forecasting a line of storms to develop from Kansas all the way south into central Texas along the frontal boundary (I'm expecting rainfall totals between 0.25 to as much as an inch in spots across the area thanks to Sunday's storms. Some areas may receive significantly less. It all depends on how solid the line of storms is when it moves through the area. If there are lots of gaps in the line of storms, as I'm expecting there will be, many folks may be left with little to no rainfall accumulation---Hope I'm wrong)
Long Range Outlook:
Cooler weather moves in behind the front on Monday with highs dropping into the 60s for highs; 40s expected across the area Monday night/Tuesday morning of next week. Clouds quickly increase across the area by Tuesday of next week ahead of another weather disturbance that will bring us several days of light rain chances by the middle/end of next week. Highs only in the 50s Tuesday/Wednesday with light rain possible Wednesday through Friday ahead of another front that as or right now, looks to drop highs into the 50s for the days leading up to Christmas with lows in the 30s and 40s...the general pattern for Christmas week looks cooler with some long range models predicting a possible freeze after Christmas Day. Of course, forecasting that far out in the future should be taken lightly and please understand that nothing is set in stone when it comes to the weather.
