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Tonight’s Severe Weather Chances & SPC’s New Classification System

March 25th, 2015 at 3:26 pm by under Weather

The new models are out, and they are beginning to hint at lower severe weather probabilities for this evening.  We still may see a thunderstorm or two, but the chances of any local storm reaching severe criteria is small.  So, what makes a storm a severe storm?  Well, for the title to be achieved, two of the these three criteria must be met:

1.  Winds 58mph or better

2.  Hail the size of a quarter or bigger (greater than or equal to 1″ in diameter)

3.  Any tornadic activity (funnel cloud/tornado)

 

The Storm Prediction Center

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The Storm Prediction Center (SPC), located in Norman, Oklahoma, is tasked with forecasting the risk of severe thunderstorms and tornadoes across the United States. The agency issues convective outlooks, mesoscale discussions, and watches as a part of this process.

This year, the convective outlook product has taken on a new look, as the SPC decided to expand upon their prediction classification system.  In the past, the threat for severe weather was either labeled slight, moderate, or high.  This severe weather season, you will notice two more classifications;  ENHANCED and MARGINAL.

So, if you see, for example, an enhanced risk area over your community, what does it mean??  Well, here is a breakdown:

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1.  Marginal/dark green risk area –  Includes severe storms of either limited organization and longevity, or very low coverage and marginal intensity.

2.  Slight/yellow risk area – Implies organized severe thunderstorms are expected, but usually in low coverage with varying levels of intensity.

3.  Enhanced/orange risk area – Depicts a greater concentration of organized severe thunderstorms with varying levels of intensity.

4.  Moderate/red risk area - Indicates potential for widespread severe weather with several tornadoes and/or numerous severe thunderstorms, some of which may be intense.

5.  High/magenta risk area - Suggests a severe weather outbreak is expected from either numerous intense and long-track tornadoes, or a long-lived derecho system with hurricane-force wind gusts producing widespread damage.

**The light green area above is labeled “TSTM” for “Thunderstorm.”  This area indicates a 10% or higher probability of thunderstorms forecast during the valid period.**

 

Now that the Spring season is upon us, don’t forget to download our KXAN Severe Weather Guide!!  It’s a great refresher in case you and your family get caught in a severe weather situation.

 


Friday 10PM Update – Flash Flood Potential

March 20th, 2015 at 9:48 pm by under Weather

2-6 Radar


FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH SATURDAY EVENING
A SLOW MOVING COLD FRONT WILL INTERACT WITH A DEEP PLUME OF MOISTURE TO PRODUCE MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS ACROSS SOUTH CENTRAL TEXAS THIS AFTERNOON THROUGH SATURDAY EVENING. LOW WATER CROSSINGS AND AREAS PRONE TO FLOODING WILL BE AT RISK OF BEING IMPACTED WITH ROADS POSSIBLY IMPASSABLE IN SOME LOCATIONS. THE HEAVIEST RAINFALL IS EXPECTED THIS AFTERNOON THROUGH SATURDAY MORNING. THE RISK FOR HEAVY RAINFALL AND FLASH FLOODING  WILL DIMINISH SATURDAY EVENING.
DETAILS:

* WIDESPREAD 2 TO 4 INCHES OF RAINFALL WITH ISOLATED TOTALS OF 6
  TO 7 INCHES FROM MULTIPLE ROUNDS OF MODERATE TO HEAVY SHOWERS
  AND THUNDERSTORMS.

* RAPID RUNOFF FROM HEAVY RAINFALL WILL LIKELY RESULT IN FLASH
  FLOODING OF CREEKS AND STREAMS...LOW WATER CROSSINGS...AND
  URBAN AREAS NORMALLY SUBJECT TO FLOODING. RECENT RAINFALL
  ALONG AND EAST OF INTERSTATE 35 OVER THE PAST FEW WEEKS HAS
  LED TO SATURATED SOILS WHICH MAY CAUSE FLASH FLOODING TO OCCUR
  WITH LESS RAINFALL THAN USUAL...POSING AN ELEVATED THREAT TO
  LIFE AND PROPERTY.

WHAT TO DO:

A FLASH FLOOD WATCH MEANS FLASH FLOODING IS POSSIBLE IN OR NEAR
THE WATCH AREA. IF YOU ARE IN THE WATCH AREA...PLAN NOW FOR WHAT
YOU WILL DO IF FLASH FLOODING DEVELOPS. STAY INFORMED AND BE
READY TO ACT IF YOU SEE FLOODING OR IF A FLASH FLOOD WARNING IS
ISSUED.

1 SPC

1 SPC

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Flash Flood Watch Details

March 19th, 2015 at 9:32 pm by under Weather

1 SPC

911 PM CDT THU MAR 19 2015

...HEAVY RAINFALL LIKELY FRIDAY AFTERNOON THROUGH LATE SATURDAY...

.A SLOW MOVING COLD FRONT WILL INTERACT WITH A DEEP PLUME OF
PACIFIC MOISTURE TO PRODUCE MULTIPLE ROUNDS OF SHOWERS AND
THUNDERSTORMS ACROSS SOUTH CENTRAL TEXAS LATE FRIDAY AFTERNOON
THROUGH EARLY SATURDAY EVENING. THE HEAVIEST RAINFALL IS EXPECTED
FRIDAY EVENING THROUGH SATURDAY MORNING AS AN UPPER LEVEL
DISTURBANCE FROM MEXICO PROVIDES ADDITIONAL FORCING ALONG THE
FRONT WHICH WILL BECOME NEARLY STATIONARY OVERNIGHT. DRIER
CONDITIONS WILL MOVE INTO THE AREA LATE SATURDAY AFTERNOON AND
EVENING AS THE UPPER LEVEL DISTURBANCE MOVES OUT OF THE REGION.

THE FLASH FLOOD WATCH CONTINUES

* FROM FRIDAY AFTERNOON THROUGH SATURDAY EVENING

* WIDESPREAD 2 TO 5 INCHES OF RAINFALL WITH ISOLATED TOTALS OF 6
  TO 8 INCHES FROM SLOW MOVING AND TRAINING THUNDERSTORMS.

* RAPID RUNOFF FROM HEAVY RAINFALL WILL LIKELY RESULT IN FLASH
  FLOODING OF CREEKS AND STREAMS...LOW WATER CROSSINGS...AND
  URBAN AREAS NORMALLY SUBJECT TO FLOODING. RECENT RAINFALL
  ALONG AND EAST OF INTERSTATE 35 OVER THE PAST FEW WEEKS HAS
  LED TO SATURATED SOILS WHICH MAY CAUSE FLASH FLOODING TO OCCUR
  WITH LESS RAINFALL THAN USUAL...POSING AN ELEVATED THREAT TO
  LIFE AND PROPERTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS FLASH FLOODING IS POSSIBLE IN OR NEAR
THE WATCH AREA. IF YOU ARE IN THE WATCH AREA...PLAN NOW FOR WHAT
YOU WILL DO IF FLASH FLOODING DEVELOPS. STAY INFORMED AND BE
READY TO ACT IF YOU SEE FLOODING OR IF A FLASH FLOOD WARNING IS
ISSUED.

1 SPC

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1 SPC

1 SPC


A New World Snow Record?

March 11th, 2015 at 10:39 pm by under Weather

If this verifies…. Well needless to say… It will be absolutely incredible!!

FROM THE WASHINGTON POST:

Hourly Forecast

 

World record? 100 inches of snow may have clobbered Italy in 18 hours, review pending

 

 

The Italian weather Website MeteoWeb reports that Capracotta, Italy saw 100.8 inches of snow in just 18 hours on Thursday, March 5 — a total that, if verified, would set a new world record for snowfall in a 24-hour period.

However, the reports from Capracotta as this time are not official.

An investigation of the measurement by the World Meteorological Organization would need to be conducted in order for this to go down in the “official” record books, but the WMO does not currently track snowfall for any location. According to Randall Cerveny, WMO’s chief rapporteur ofweather and climate extremes, this is because accurate snowfall measurements are fairly limited, and have been “markedly difficult” to verify.

But there is hope for an investigation of the Italy total. “The WMO is currently evaluating the addition of world snowfall extremes as a new category for the WMO Archive of Weather and Climate Extremes,” said Cerveny. “We will likely be adding it to the Archive in the near future.  When we do so, we certainly will be investigating this interesting report from Italy as a possible record snowfall extreme.”

snow

Snowfall records are notoriously difficult to pin down. Official snowfall measurements in the U.S. involve the use of a “snowboard” — typically just a 16 by 16 inch piece of plywood painted white — which is cleared at the time of each measurement. But even if you use the correct tools, you can still mess up a snow total. “Even making snowfall measurements too oftencan affect the total snowfall value as snow compression is a critical factor in snowfall measurement,” says Cerveny.

The U.S., Canada and Japan have strict snowfall measuring procedures, and reports from these countries have widely been accepted as “world records” by meteorologists, if not officially by the WMO. If Capracotta’s snow total is eventually verified, it would surpass the currently accepted world record by just over 10 inches – 90.6 inches (about 7.5 feet) in Mount Ibuki, Japan, on Feb. 14, 1927.

On April 14-15, 1921, 75.8 inches of snow fell in Silver Lake, Colo., and that measurement still holds the U.S. record for most snow in a 24-hour period.

Even if the WMO does decide to take up snowfall records, it would be quite a while for the investigation to conclude. Investigations include both internal committees, and climatologist and meteorologists from the observing country (in this case, Italy). “Those committees discuss all aspects of the event (such as equipment, monitoring techniques, site location) and then recommend to the WMO chief Rapporteur … whether or not to accept the event as an official world record weather extreme,” said Cerveny. “When that decision is made, we then issue an announcement through the WMO offices in Geneva.”

Hourly Forecast

One recent and notable record investigation by the WMO was the overturning of the world’s hottest temperature — previously 132.8 degrees in El Azizia, Libya in 1922. The committees found that the measurement was erroneous, which elevated Death Valley’s temperature of 129.2 degrees in 1913 to the world record.


The Cool & Wet Stretch To Continue?

March 11th, 2015 at 9:48 pm by under Weather

The seemingly never ending weather pattern that has been delivering Central Texas and the better part of the eastern 2/3 of the United States below average temperatures and abundant wet weather, may continue into the Spring season according to the Climate Prediction Center.  Here is a recap of the month of March thus-far, as it has started in a very similar fashion to how the month of February finished:

1 SPC

1 SPC

Here are the latest temperature and precipitation outlooks through the Spring season:

8-14 Day Temperature Outlook

8-14 Day Temperature Outlook

 

8 - 14 Day Precipitation Outlook

8 – 14 Day Precipitation Outlook

 

Three Month Temperature Outlook

Three Month Temperature Outlook

Three Month Temperature Outlook

Three Month Temperature Outlook

 

 

 

 


An In Depth Look At Our Flash Flood Potential

March 8th, 2015 at 9:49 pm by under Weather

Here is the very latest from the National Weather Service, in regards to the FLASH FLOOD WATCH that covers over half of the KXAN viewing area.  Also, take a look at the two in house models we have here in the KXAN First Warning Weather Center.  If these prove to be correct, some rain gauges, and low water crossings may be overflowing  tomorrow afternoon.

LOCALLY HEAVY RAINFALL TONIGHT THROUGH MONDAY......
A SERIES OF DISTURBANCES WILL INTERACT WITH A PLUME OF MOISTURE
FROM THE PACIFIC AND WILL CONTINUE TO PRODUCE ROUNDS OF SHOWERS
AND ISOLATED THUNDERSTORMS ACROSS SOUTH-CENTRAL TEXAS THIS
AFTERNOON THROUGH EARLY MONDAY EVENING. THE HEAVIEST RAINFALL IS
LIKELY TO OCCUR LATE TONIGHT THROUGH MONDAY AFTERNOON. DRIER
CONDITIONS WORK INTO THE AREA MONDAY NIGHT FROM WEST TO EAST.
FLASH FLOOD WATCH REMAINS IN EFFECT FROM 7 PM CDT THIS EVENING
THROUGH MONDAY EVENING...

THE FLASH FLOOD WATCH CONTINUES FOR

* A PORTION OF SOUTH CENTRAL TEXAS...INCLUDING THE FOLLOWING
  AREAS...ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...
  BURNET...CALDWELL...COMAL...DE WITT...FAYETTE...FRIO...
  GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...LAVACA...
  LEE...MEDINA...TRAVIS...WILLIAMSON AND WILSON.

* NOW THROUGH MONDAY EVENING

* WIDESPREAD 2 TO 4 INCHES OF RAINFALL IS EXPECTED WITH ISOLATED
  POCKETS UP TO 6 INCHES.

* RAPID RUNOFF FROM THESE HEAVY RAINS COULD RESULT IN FLASH
  FLOODING OF CREEKS AND STREAMS...LOW WATER CROSSINGS...URBAN
  AREAS NORMALLY SUBJECT TO FLOODING...AS WELL AS A THREAT TO
  LIFE AND PROPERTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS FLASH FLOODING IS POSSIBLE IN OR NEAR
THE WATCH AREA. IF YOU ARE IN THE WATCH AREA...PLAN NOW FOR WHAT
YOU WILL DO IF FLASH FLOODING DEVELOPS. STAY INFORMED AND BE
READY TO ACT IF YOU SEE FLOODING OR IF A FLASH FLOOD WARNING IS
ISSUED.

2-7 Temps

1 SPC

3-8 FFW

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1 SPC


WINTER STORM WARNINGS AND ADVISORIES

March 4th, 2015 at 11:02 am by under Weather

Here is the latest information from the National Weather Service as of 11:00AM Wednesday:

 

NWS

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WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO NOON
CST THURSDAY...

THE NATIONAL WEATHER SERVICE IN AUSTIN/SAN ANTONIO HAS ISSUED A
WINTER STORM WARNING FOR FREEZING RAIN AND SLEET...WHICH IS IN
EFFECT FROM MIDNIGHT TONIGHT TO NOON CST THURSDAY.

* TIMING...ARCTIC AIR WILL POUR INTO THE AREA AFTER 6
  PM...FREEZING RAIN AND SLEET SHOULD BEGIN AROUND MIDNIGHT AND
  CONTINUE THROUGH NOON THURSDAY. TEMPERATURES SHOULD RISE ABOVE
  FREEZING AFTER NOON THURSDAY.

* MAIN IMPACT...FREEZING RAIN AND SLEET CAUSING ICING OF 1/10 INCH
  AND POSSIBLY A LITTLE HIGHER. THIS WILL MAKE FOR ICY ROADS AND
  HAZARDOUS DRIVING CONDITIONS.

* OTHER IMPACTS...SIDEWALKS...DECKS...AND OTHER SURFACES MAY BE
  DIFFICULT TO WALK ON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS ACCUMULATIONS OF SNOW...SLEET...
FREEZING RAIN OR FREEZING DRIZZLE ARE EXPECTED OR OCCURRING. THIS
WILL CAUSE CONSIDERABLE TRAVEL PROBLEMS AND MAY POSE A THREAT TO
LIFE AND PROPERTY.




An Early Look At Our Next Chance For Ice

March 1st, 2015 at 8:30 pm by under Weather

Here is the latest from the National Weather Service, regarding the possibility of Central Texas ice…… Again….

Remember, it is only Sunday evening, and models will most likely shift timing, and the freezing line location by Wednesday evening.  Therefore, keep an eye on the forecast between now, and the middle of this week.  We’ll have numerous up to the minute updates on KXAN, KXAN.com, and on our KXAN Weather App.  Have a great week and stay warm!!

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Another strong arctic front is scheduled to move through the area Wednesday afternoon. Showers and thunderstorms will be possible ahead and just behind the front, but as cold air filters into the area, freezing rain/sleet/snow will be possible for areas in white. It is too early to get into specifics regarding accumulations and impacts, but areas north of the pink line will see the coldest temperatures. Stay tuned over the next few days for updates as confidence increases one way or the other


Last Update On The Wintry Weather From NWS

February 28th, 2015 at 3:39 pm by under Weather
All Winter Storm Warnings and Winter Weather Advisories along and south of a Kerr to Llano to Williamson County line have been allowed to expire.  
 **WINTER WEATHER ADVISORIES continue for Mason and San Saba Counties through 6PM Saturday**
Overview:
Temperatures have risen above freezing across Travis and Williamson counties.  Temperatures are still below freezing across some areas of the northern Hill Country.  There could still be some patchy light freezing rain or freezing drizzle along and north of a Marble Falls to Blanco to Kerrville line through the remainder of the afternoon.  Any additional accumulation amounts are expected to be very light.  However, those traveling through the region should still exercise caution due to earlier icing this morning, especially over bridges and overpasses.  Elsewhere, patchy drizzle and light rain will continue today through tomorrow.  Temperatures tonight rising across the Hill Country into the mid and upper 30s, and elsewhere in the 40s. 
 
Next Week:
A heads up for next week, weather models have been indicating another possibility of wintry precipitation Wednesday night into Thursday morning across the Hill Country and Central Texas.  At this time it is too soon to determine with high certainty the precipitation type, exact amounts and exact locations.  However, stay tuned next week for potential email briefings if trends continue towards another round of winter precipitation.
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Latest NWS Update For The Winter Weather Advisory

February 27th, 2015 at 5:40 pm by under Weather
1 SPC
A Winter Weather Advisory is in effect until 10 am Saturday for the entire Hill country, I-35 corridor, Metro Austin, and Metro San Antonio. Numerous Reports of Icing across Williamson, Burnet, and Gillispie County. 
Area of Concern:
The primary area will be roughly from Taylor in eastern Williamson County to the southwest border of Bexar County, and along and west of U.S. 90 from San Antonio to Del Rio. This does include All of Metro Austin and Metro northern San Antonio.
 
Threats & Impacts:

Expected Accumulations: We expect light amounts of 1/10 inch or less freezing drizzle in the advisory area.
Impacts:  The primary impacts are expected to be slippery spots, primarily on bridges, overpasses, less traveled roads, and other elevated surfaces (e.g., backyard decks).
Timing and Overview:
Freezing drizzle is on the increase at the present time and numerous reports of icing mainly on bridges and overpasses have come into the office. In the attached image, most of the moderate impacts have been in the yellow shaded region. Locations in the pink area can quickly see impacts as the night progresses. The most significant impacts will be where temperatures have dropped below 30 degrees. Precipitation is light but it only takes a little to cause moderate impacts of ice. The freezing drizzle should continue for most of the night with a nearly steady temperature. Temperatures should warm above freezing around 9-10 AM Saturday morning. 
Confidence:
High for the temperatures being cold, High for freezing precipitation and amounts.
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NWS