Friday, January 23, 2015

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 1st, 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…)


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:

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***



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