Winter to Spring back to Winter

Weather Discussion:

TGIF Everybody! Between Wednesday afternoon and now we have officially picked up 2.63 inches of rain at Camp Mabry and 3.26 inches of rain at the airport. That is great news! Unfortunately, the heaviest rains fell along and east of the Interstate 35 corridor. Lake Travis is only 0.60 inches higher than it was back when the rains started on Wednesday. Since January 1^st, we have picked up 4.71 inches of rain at Mabry and 5.02 inches at the airport. Average January rainfall for Austin is around 2.22 inches, so, as you can see, we are running above normal in the rainfall category for the month, WOO HOO! Always great to see above normal rainfall totals in a drought.

Latest Drought Monitor (image below) released yesterday shows Austin in the abnormally dry category with San Antonio and southern and western portions of south central Texas in the moderate to extreme drought category. About 41% of the state is in at least moderate drought.

Rainfall Totals (Inches) from across south central Texas (Wednesday through Friday):

LCRA Hydromet (Awesome resource for temps, rainfall, lake levels, etc…)

http://hydromet.lcra.org/full.aspx#

Austin (Mabry): 2.63

Austin (A.B.I.A.): 3.26

Bull Creek at Loop 360: 2.52

Barton Creek at Loop 360: 3.19

Walnut Creek at Webberville Road: 3.30

Lakeway: 2.97

Lago Vista: 1.90

Marble Falls: 1.32

Burnet: 1.33

Dripping Springs: 2.81

Johnson City: 2.14

Llano: 0.83

Fredericksburg: 1.06

Mason: 1.01

Cedar Creek: 3.72

Bastrop: 1.71

La Grange: 1.16

The upper level low responsible for the widespread rain and wintry precipitation across Texas over the past several days is finally beginning to push off to east. Behind the system, drier air is beginning to move into the mid/upper levels of the atmosphere as high pressure begins to take control of our weather for the weekend and much of next week. This upper level low is now moving off to the northeast where they are just now beginning to feel its effects. Wind, rain, and snow will be spreading across much of the Mid-Atlantic and New England over the weekend thanks to a strengthening area of surface low pressure now located across the northeastern Gulf of Mexico. That surface low actually developed along the Texas Coast just yesterday and will be moving just off of the New England Coast this weekend. As that surface low continues to push to the northeast it is expected to undergo “Bombogenesis”, which basically means the pressure in the storm is expected to drop 24 mb (degrees of pressure) or more within 24 hours. The lower the pressure, the stronger the storm.

Here’s a great explanation from The Weather Channel:

http://www.weather.com/storms/winter/video/what-is-bombogenesis

Here’s a look at forecast mean sea level pressure and precipitation across northeastern U.S. on Saturday:

Long Range Forecast Discussion:

No rain expected tomorrow (Saturday) through Thursday of next week as high pressure at the surface and aloft will be in control of our weather. That means get ready for a warming trend and highs in the 70s for a majority of next week. Things start to change in a hurry though by the end of next week into the weekend as a ridge of high pressure develops along the west coast and an upper level low develops over northwestern Mexico and the Baja Peninsula. That ridging along the west coast will push cold Arctic Air south into the central and eastern lower 48 and that area of low pressure over northwestern Mexico will create what looks right now to be another overrunning type weather pattern for next weekend into the beginning of the following week. Warm, moist air will be forced to rise up and over the cold, dense air expected to be in place at the surface behind a strong cold front that looks as of right now to move through south central Texas Saturday morning. Latest forecast model shows a decent chance for rain along and mainly behind the front Saturday afternoon through Monday of the following week. It also looks like parts of the state will be dealing with some more wintry precipitation. Way too soon to say if we are going to get any snow/ice here in central Texas, however, it bears watching. Of course this forecast is subject to change as we will have plenty of time to watch how things play out over the next week. If you take anything from the discussion above, plan on warming/dry (above normal temps) weather beginning this weekend and persisting through Thursday of next week. Clouds look to thicken by next Friday ahead of the front, with a major drop in temperatures expected by Saturday afternoon falling from the 60s and 70s for highs back into the 30s and 40s with clouds and rain returning for the remainder of next weekend. The roller coaster continues!!!

500 mb forecast NOON Tuesday (wind flow/pressure at around 18,500 feet above the surface and is very useful for finding ridges of high pressure and troughs of low pressure) In this image a ridge of high pressure clearly visible across the center of the country with a deep trough over the east.  

500 mb Forecast Map for Saturday Morning: Strong ridge of high pressure over the west coast -represented by the big blue H-and the big red L over Hudson Bay, the infamous Polar Vortex (basically a large mass of bitterly cold Arctic Air that sits on top of the Arctic Circle for a majority of the year) will work together to send frigid, Arctic Air into the central and eastern U.S. by the end of next week into next weekend. The smaller red L over the Baja is an upper level low that will send disturbances/Pacific moisture over Texas (green arrows) over/on top of the Arctic Air at the surface. The white arrows represent the position of the Polar Jet Stream (when that jet stream decides to dip south watch out, it means cold weather for us here in the lower 48)

Long range forecast model predicting BELOW AVERAGE temperatures across a majority of the central and eastern U.S. next weekend...the brunt of the coldest air looks to miss Texas to the east, however, it will still be quite chilly around here with highs in the 30s and 40s expected. Blues/purples and pinks represent BELOW AVERAGE temperatures.

Forecast Temperatures across the nation Superbowl Sunday BRRR!!!:

Red arrow represents location of the Super Bowl (Glendale, AZ) at the University of Phoenix Stadium

Day by Day Long Range Forecast:

Tonight: Low level clouds will slowly erode across the area as drier air moves into the area, however, lots of mid and high level clouds will stream across the area overnight as Pacific Moisture streams across Texas in the mid/upper levels of the atmosphere on the backside of the upper level low that brought us all of the rain over the past several days. So, let’s call it partly to mostly clear and chilly with lows dropping into the 30s area wide. Low-lying, out-lying areas may receive a light freeze. Honestly, how cold we get tonight is going to be dependent on how thick the clouds are over the area.

Saturday: Mainly sunny & WARMER with highs near average for this time of year in the lower 60s

Saturday Night: Mostly clear & chilly with lows in the upper 30s to lower 40s; patchy fog may develop

Sunday: Mainly Sunny & BEAUTIFUL with highs in the upper 60s to near 70°F

Sunday Night: Mostly clear and chilly with lows in the lower 40s

Monday: Sunny & BEAUTIFUL with highs in the lower 70s

Monday Night: Mostly clear & chilly with lows in the 40s

Tuesday: Sunny & much warmer with highs in the lower to middle 70s

Wednesday: Sunny with highs in the 70s

Thursday: Mostly sunny with highs in the 70s

Friday: Mostly cloudy with highs near 70°F

Saturday: Mild start to the day finishes cold and windy as an Arctic Front moves through the area by midday bringing widespread clouds and rain…60s dropping into the 40s!! Winter Returns!!!

Sunday: Wet, cold and breezy with highs in the 30s to near 40°F

***Please note that this forecast is by no means set in stone and is definitely and most likely to change over the coming days, however, the general trend for above normal highs majority of next week with colder and wetter weather arriving for next weekend looks to be a good outlook as of right now…thanks for reading my blog***

Spring Tuesday, Winter Thursday

FORECAST DISCUSSION: 

We officially topped out at 75°F this afternoon at Camp Mabry thanks to abundant sunshine and a southwesterly wind. The airport officially topped out at 72°F. I’ve got my eyes on a cold front and a developing trough of low pressure that will be affecting south central Texas over the coming days. While the past few days have been gorgeous, the dry, mild, and breezy weather has really allowed for the cedar pollen to explode and spread. The highest cedar count of the season, so far, occurred today at the KVUE-TV Studios in north Austin. Meteorologists there recorded over 5,500 grains of cedar pollen per cubic meter. The rain Wednesday Night and Thursday should wash that pollen out of the air.

  

Day-by-Day Forecast:

Tonight: Mostly clear & cool with lows in the 40s area wide

Tuesday: Mostly sunny & warm with highs in the 70s ahead of a late afternoon/early evening cold front that will shift winds from the southwest to the north by Tuesday evening across the area. That shift in the wind will allow cooler air to filter into the area.

Forecast Highs - NAM 4K Hi-Res Model (Check out the low 80s southwest of San Antonio!)

Tuesday Night: Mainly clear & chilly with lows in the 40s; north breeze will make it feel brisk; clouds increase late

Wednesday: Mainly cloudy & much cooler with highs in the upper 50s to lower 60s area wide; clouds thicken during the day in response to the approaching upper level trough/low pressure system. Warmer, moist air will be forced to ride up and over the cooler air at the surface. This is a common weather set-up across south central Texas during the winter months. Showers will increase from the west and southwest through the day with rain becoming likely by the evening hours across a majority of the area.

Wednesday Night: Showers and thundershowers likely with lows in the 40s area wide

Thursday: Cold, rainy, and breezy with highs staying steady in the 40s; pockets of moderate rain likely with some embedded lightning/thunder…many areas look to receive between 0.75 to as much as 1.25 inches of rain. Higher accumulations between 1.50 to as much as 2 inches not out of the question; especially for areas east of the I-35 corridor. The majority of the rain looks to shift east of the area by late afternoon.

Simulated Radar (NAM 12 Model) for 9 a.m. Thursday: Widespread rain from central, north, east, and southeast Texas...snow possible across the Panhandle and eastern New Mexico!

Thursday Afternoon Temperatures: 40s!!! Cold, wet, and windy

Thursday Night: Cloudy and cold with lows in the mid to upper 30s area wide; scattered light rain showers possible; All of the area looks to stay ABOVE FREEZING

Friday: Partly sunny & cool with highs in the 50s; a brief sprinkle or light rain shower possible during the morning hours

Friday Night: Clearing skies and chilly with lows in the 30s

Saturday: Mostly sunny & pleasant with highs in the low to mid 60s

Saturday Night: Mainly clear & cool with lows in the 30s & 40s

Sunday: Sunny & BEAUTIFUL with highs in the 60s

FORECAST RAINFALL TOTALS:

GFS Model:

NAM Model:

ECMWF Model:

For all of you Arctic Air fans, long range models are not forecasting any Arctic Air Outbreaks over the next two weeks for Texas. Of course that can change. Arctic Fronts can move through the area as late as early March. 

Arctic Parade

FORECAST DISCUSSION:

After hitting a high of 71ºF this afternoon at Camp Mabry it is time to brace yourselves for some BIG changes. A strong Arctic Cold Front will plunge through south central Texas late tonight into early Wednesday morning. Strong north winds will move in behind the front and allow cold, Arctic air to settle into the region. Highs on Wednesday will struggle to climb into the mid 40s under a mostly sunny sky. The brunt of the cold air moves in late Wednesday into Thursday morning when all of south central Texas will fall into the 20s! Don’t be surprised to see some upper 10s across the Hill Country. Remember the 4 P’s: Plants, pipes, people and pets. A reinforcing Arctic front moves through central Texas early Friday morning keeping highs in the 30s for Friday and Saturday [more info. below]

Strong Arctic High Pressure Cell [a.k.a. SIBERIAN HIGH] will take over a good chunk of the central and Eastern U.S. over the coming days. An Arctic High is simply an incredibly cold and strong built up mass of Arctic Air. This Arctic High will ensure a long stretch of well below normal temperatures not only us here in Texas, but for the majority of the lower 48 east of the Rocky Mountains:

Notice on the map below how tight the black lines [isobars=lines of equal pressure] are on the outer periphery of the center of the high pressure cell which is forecast by the GFS Model to be over the South Dakota and Nebraska Border noon Wednesday. The closer the black lines are to each other, the windier it is! So, just by looking at this map get ready for a WINDY Wednesday!

Just for fun, the image below is an archived image of the same type of map you are looking at above from the December 1989 Historic Arctic Outbreak that brought us a low of 4ºF here in Austin just before Christmas of 1989, it sure is interesting to see just how similar those maps look! I'm not saying we are going to see single digits here in Austin, however, it is incredible to think just how strong this Arctic High moving in over the coming days is going to be: If you are interested in reading up on the December 1989 Arctic Outbreak click HERE.

This chart is a look at official high and low temperatures recorded in Austin during that Arctic Outbreak: Dec. 21st through Dec. 24th 1989

Information from Left to Right:

Date-High-Low-Average Temperature-Departure from normal

Wednesday Night/Thursday Morning Forecast Lows (NAM 4km Model):

As an upper level disturbance approaches from the west Friday and passes over the area on Saturday there is the chance for light rain to develop across the area. Given the cold temperatures in place, freezing rain/drizzle and sleet [ice pellets] are not out of the question for the area late Friday into Saturday. There is still a fair amount of uncertainty with this forecast, however, it is beginning to look like travel may become impacted late Friday into Saturday for areas along and west of I-35. Temperature forecasts will need to be monitored carefully. If the air turns out to be colder than models are currently suggesting, freezing rain may become an issue for all of south central Texas. Please monitor the weather carefully over the coming days and heed all watches/warnings/advisories issued by the National Weather Service.

Day by Day Forecast:

***High and Low temperatures below represent Austin Metro Area***

Tonight: Mostly clear and cool; north winds pickup overnight as Arctic Front moves through; we will wake up to temperatures as cold as the lower 30s across the northwestern Hill Country to as “warm” as the lower 40s across the remainder of the area.

LO: 39ºF

Wednesday: Mainly sunny, WINDY, and MUCH COLDER with highs in the 40s; North winds sustained 15-25 mph with gusts as high as 35-40 mph possible at times. Latest models show us spending a majority of the afternoon in the upper 30s and lower 40s quickly dropping into the 30s area wide by sunset.

HI: 45ºF (Lower 40s north, upper 40s south)

Wednesday Night: Area wide HARD FREEZE with lows in the 20s area wide; upper teens possible across the Hill Country. 

LO: 23-25ºF

Thursday: FRIGID START in the 20s (wind chills in the 10s) will give way to a partly sunny & COLD afternoon with highs in the upper 30s and lower 40s across the region

HI: 40ºF [if clouds are heavier we may not make 40ºF]

Thursday Night: Increasing clouds & COLD with lows dipping into the upper 20s and lower 30s area wide; Austin and points south and east may stay just above freezing

LO: 33ºF

Friday: Cloudy & COLD as another reinforcing Arctic front moves in with a 30% chance for afternoon light rain showers; temperatures likely to stay in the mid to upper 30s all day

HI: 39ºF

Friday Night: 50% chance of wintry mix (freezing rain & sleet [ice pellets] possible especially for areas along and west of the I-35 corridor) Temperatures expected to be at/below freezing along and west of I-35 with temperatures possibly remaining 1-2ºF above freezing for areas south and east of Austin

LO: 30º (colder west in the upper 20s)

Saturday: 50% chance of AM freezing rain/sleet mix along and west of I-35; cold rain for southern and eastern areas; otherwise, cloudy and cold with highs in the 30s

HI: 35ºF 

GFS Model 18Z Run:

This high resolution model has been persistently showing a rather large area of freezing rain mixed with sleet [ice pellets] over south central Texas beginning late Friday into early Saturday and clearing out by late Saturday afternoon/early evening (PINK ON MAP REPRESENTS THE FORECASTED WINTRY PRECIP & GREEN REPRESENTS A COLD RAIN)

Seven Day Forecast:

***PLEASE UNDERSTAND THAT THIS FORECAST IS SUBJECT TO CHANGE***

***ALL OF THE FORECAST MODELS SHOWN ABOVE ARE AVAILABLE/COURTESY OF TROPICAL TIDBITS*** THIS IS THE LINK:

http://www.tropicaltidbits.com/analysis/models/