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The pattern of widespread rain which set up across the area late last week has come to an end.  That area of disturbed weather which pushed inland out of the Gulf of Mexico late Friday was located Monday morning over northern Mexico.  While much of the deep, tropical moisture has shifted to the west with this system, Monday's analysis showed a fair amount of moisture still remaining across the Central and South Texas.  Due to this lingering moisture, there will be a slight chance for a few isolated rain showers and thunderstorms across the region this afternoon and evening.  The probability for rain at any given location will only be near 20 percent.  Rain totals, if any, will average less than a quarter inch.  Today's sky will be partly cloudy and conditions will be warm and quite humid.  Today's temperature will generally warm to the low 90s.

For Tuesday through Wednesday, little change in the pattern is expected.  A couple of isolated rain showers and thunderstorms will be possible each afternoon, but the probability for rain will be less than 20 percent.  Conditions will be mostly sunny, warm and humid with high temperatures generally in the low to middle 90s.

A change in the weather pattern is predicted to take place Thursday when the broad ridge of high pressure over Texas shifts to the east, allowing a series of low pressure troughs to begin lifting north out of Mexico.  These troughs will pull moisture north from the Gulf of Mexico, resulting in the development of scattered rain showers and thunderstorms.  The probability for rain will be around 30 percent Thursday and near 40 percent Friday.  A partly to mostly cloudy sky is forecast both days, with daily high temperatures of 88-90 degrees.  Rain amount over the 2-day period are forecast to total less than a half inch.

The wet and unsettled weather pattern is forecast to continue Saturday through Sunday as additional low pressure troughs lift north out of Mexico.  These systems will cause the sky to remain mostly cloudy.  There will be a 30-40 percent chance for rain showers and scattered thunderstorms on both days.  Rain amounts over the weekend are forecast to total close to a half inch.  High temperatures will be in the upper 80s.

Forecast solutions indicate the unsettled weather pattern will continue into early next week, with at least a slight chance for rain showers and thunderstorms forecast for Monday and Tuesday.  Rain amounts are not shaping up to be very heavy, with most totals staying below a quarter inch.  High temperatures both days will be near 90 degrees.  Partly cloudy and warm weather is forecast next Wednesday and Thursday.  There are signs a Canadian cold front will attempt to push south into Texas sometime late next week or the following weekend.

One item to watch for late this week and into the upcoming weekend will be an area of disturbed weather currently located in the eastern Pacific Ocean, a few hundred miles south of Baja, California.  National Hurricane Center forecasters state this system will likely become a tropical depression later this week as it tracks north toward Baja, California and northwestern Mexico.  Depending in the eventual path of this system, it is possible some of this system's moisture could be pulled northeastward into Texas. Stay tuned for more details on the progress of this system.

Tropical Weather Update

The tropical Atlantic basin has quieted down from the very active pattern that was in place last week.  Tropical Depression Florence was located along the border between Kentucky and Ohio, about 240 miles west of Charlottesville, Virginia.  Florence is moving to the northeast at 15 mph and is forecast to become extratropical late today while accelerating to the east-northeast.

Tropical Depression Joyce was located over the northeastern Atlantic, about 285 miles south-southwest of the Azores.  The depression is moving toward the east-southeast near 8 mph and this forward speed is expected to continue while turning toward the southeast today, south on Tuesday, and southwest on Wednesday.  Maximum sustained winds are near 35 mph.  Some weakening is forecast during the next 48 hours and Joyce is expected to become a remnant low tonight or Tuesday.

National Hurricane Center forecasters continue to monitor an area of disorganized showers and thunderstorms extending from just west of Jamaica to eastern Cuba and Hispaniola.  This activity is associated with the remnants of Isaac.  Environmental conditions are expected to remain unfavorable for re-development while the system moves westward to west-northwestward across the northwestern Caribbean Sea.  NHC forecasters are giving this system only a ten percent chance for development over the next 5 days.

RAAMB-CIRA 09/17/18 2:30 pm CDT 

The First Day of Autumn

The autumnal equinox arrives this coming Saturday, September 23, 2018, at 8:54 pm CDT.  At the equinox, days and nights are approximately equal in length.  The equinox marks the beginning of fall in the Northern Hemisphere and the beginning of spring in the southern Hemisphere.  On the equinox, the sun shines directly overhead at the equator.  It's interesting to note, the sun will rise due east and set due west on the equinox.  This fact makes the day of an equinox a good day for finding due east and due west from your yard or other favorite site for watching the sky.  Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.  The equinox is a seasonal signpost in Earth's orbit around the sun.

14-Day Rainfall Totals

Pasted below is map showing the estimated rainfall accumulation beginning September 3rd.  The highest totals of rain during this period occurred near and to the west of San Antonio, with totals of 16-20 niches.  Another area of very heavy rain occurred along the coast between Corpus Christi and Galveston, with some totals in excess of 20 inches.  LCRA's Hydromet gauge located at Matagorda, recorded a 2-week total of 17.97 inches.

NWS Rainfall Acccumulation for the period 7 am 9/3/2018 through 7 am 9/3/2018
Map courtesty National Weather Service West Gulf River Forecast Center 

Much of the Hill Country received between 5 and 8 inches of rain.  LCRA's highest gauged total across the Hill Country region was 13.22 inches in southeastern Burnet County, roughly 8 miles south-southwest of Bertram.

Across Central Texas, totals generally averaged between 3 and 5 inches, with the lowest totals occurring across Fayette and Colorado Counties.  LCRA's highest gauged total was 15.48 inches, occurring in western Bastrop County, about 3 miles west-southwest of Cedar Creek.

Across the coastal plains, totals were generally in the range of 6- 8 inches, although amounts were considerably higher across the southern half of Matagorda County.

Bob

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Here is an update on the area of disturbed weather located in the western Gulf of Mexico.  This system is shaping up to be a big rain maker for our region.  However, the threat for a high wind/organized tropical cyclone appears to be decreasing.
 

RAMMB-CIRA 09/13/18 3:15 pm CDT

Satellite data and surface observations Thursday afternoon indicated a weak low pressure center has formed over the western Gulf of Mexico, a couple of hundred miles east-southeast of Brownsville, Texas.  In addition, showers and thunderstorms in association with this system have become more numerous today.  While upper-level winds are generally conducive for development of a tropical depression, the system only has about a day before it reaches the western Gulf coast.  An Air Force Reserve Hurricane Hunter aircraft was en route to investigate the low as of mid-Thursday afternoon.  The National Hurricane Center currently has the probability for tropical development down to 50 percent.  Regardless of development, this system is forecast to bring widespread rainfall to much of the South and Central Texas Friday and this weekend.

Forecast solutions call for the disturbance to come ashore across deep South Texas sometime early Friday.  An associated surge in moisture and lift associated with the system will lead to development of widespread showers and heavy rainfall across the middle and lower Texas coast Friday morning.  A fairly widespread coverage of light to moderate rain showers is expected to slowly spread northwestward to Central Texas and parts of the Hill Country Friday afternoon.  Widespread rain showers and isolated thunderstorms look to continue across the entire region Friday night through Saturday.  The probability for rain Friday afternoon through Saturday afternoon will be around 90-100 percent.

The heaviest and most persistent rains are forecast to shift to the western Hill Country and the Rio Grande Plains Saturday night as the disturbance tracks west towards Mexico.  Occasional light to moderate rain showers will likely continue across much of the Hill Country, Central Texas and the middle Texas coast Sunday into Monday due to lingering tropical moisture.  The probability for rain both days will be near 30-40 percent.  The chance for rain should drop to just 20 percent by Tuesday.

The latest National Weather Service rainfall forecasts call for widespread totals of 2-4 inches across the area between Thursday evening and early next week.  But due to the very tropical nature of this system, isolated total of 6-8 inches will be possible.   Since the soils are very wet and in some cases saturated from recent rains, this additional rain will increase the threat for flash flooding.  The National Weather Service intends to issue a Flash Flood Watch for parts of the area Friday into Saturday.

NWS rainfall forecast for the period 7 pm Thursday through 7 pm Tuesday:

Tropical Storm Isaac 

Forecasters continue to monitor the progress of tropical storm Isaac, located Thursday afternoon near the Leeward Islands, about 220 miles south-southeast of St. Croix.
 

 RAMMB-CIRA 09/13/18 3:15 pm CDT

Isaac is moving toward the west near 16 mph.  Isaac is moving to the west at 16 mph and this general motion with a decrease in forward speed is expected for the next few days.  On the forecast track, Isaac should move farther away from the Lesser Antilles tonight, moving across the eastern and central Caribbean Sea through the weekend.  Maximum sustained winds have decreased to near 40 mph with higher gusts.  Isaac is forecast to generally weaken over the next few days, and could degenerate into a tropical wave during that time.  Tropical depression Isaac or the remnants of Isaac are forecast reach a position over the northwestern Caribbean Sea by Monday.  We will need to keep a close eye on Isaac as the system could push north into the Gulf of Mexico in the early to middle part of next week.

A Historical Note:  Today marks the ten year anniversary of Hurricane Ike making landfall along the north end of Galveston Island.

Bob

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It has been a wet week across Central and South Texas, with scattered to numerous rain showers and thunderstorms.  The highest totals have primarily been across the Hill Country where totals since Saturday have generally averaged between 2 and 4 inches.  Rainfall across the far western Hill Country over Schleicher and Sutton Counties has averaged between 5 and 7 inches.  An LCRA Hydromet gauge located near Eldorado has recorded a 7-day total of 7.89 inches, as of 2 pm.  Soils across parts of the Hill Country are beginning to become saturated.  For areas east of Interstate 35, totals this week have been considerably lower—generally around an inch, or less with some isolated heavier totals.  Towards the coast, totals this week have generally averaged between 2 and 5 inches, with the highest totals occurring across Matagorda County.

Friday's analysis showed the atmosphere across the region being very moist and fairly unstable.  In the upper atmosphere, a trough of low pressure was tracking east across the southern Plains states.  This feature was helping draw a very moist air mass from the Gulf of Mexico inland across the region.  With the atmosphere so very moist, scattered to numerous rain showers and isolated thunderstorms are forecast this afternoon.  Light to occasionally moderate rain is expected.  The probability for rain at any given location will be around 70-80 percent.  This afternoon's sky looks to stay mostly cloudy and today's temperature is forecast to only reach close to 90 degrees.

The trough of low pressure moving across the Plains states is helping to push a weak Canadian cold front south out of the Plains states.  This feature will be very important over the next couple of days as it will serve as a focus for widespread and potentially significant totals of rain.  As of midday Friday, the front was located over Northwest Texas, stretching just east of Wichita Falls to Abilene to near Fort Stockton.  Radar showed a widespread area of rain occurring along and behind the cold front.  Forecasts call for the cold front to sag south into the Hill Country Saturday and toward the coastal plains region Sunday afternoon.

High-resolution forecasts call for a widespread area of rain showers and thunderstorms to spread into the northern Hill Country around midnight and across the rest of the Hill Country Saturday morning.  Rain is forecast to persist all day Saturday into Saturday night.  There will be a 40-50 percent chance for additional rain and thunderstorms Sunday.

The large area of rain and thunderstorms is forecast to spread across Central Texas around midday Saturday, with the rain continuing Saturday night into Sunday.  The probability for rain both days will be near 70 percent.

Scattered to numerous rain showers are forecast across the coastal plains region Saturday, followed by a more widespread coverage or rain and thunderstorms Saturday night through Sunday night.  The probability for rain will be near 70 percent.

The threat for widespread rain is expected to decrease across the Hill Country Saturday evening and across Central Texas around midday Sunday.  The widespread rain should diminish across the coastal plains region around midday Monday.

A light to moderate rain intensity is predicted with most of this weekend's rains.  However, due to the large amount of tropical moisture in place, some locally heavy downpours will also be possible.  Rain amounts across the region between this afternoon and Monday morning are forecast to generally total between 2 and 3 inches, with isolated totals of 5-7 inches possible.

NWS Rainfall Forecast for the Period 7 pm Friday through 7 pm Wednesday

 
For areas that have already seen significant totals of rain, this weekend's additional rain could lead to a large amount of runoff and flash flooding.  The National Weather Service has posted a Flash Flood Watch for the northern and western Hill Country, including San Saba, Mason and Kimble Counties, through late Friday night.  The rest of the region will also see a threat for flash flooding throughout the weekend.

On Monday, the most favorable area for rain is predicted to be across the coastal plains region where the front will have stalled.  There will be a 40-50 percent chance for scattered rain showers and thunderstorms Monday through Wednesday.  Additional totals of 1-3 inches will be possible.  Across the Hill Country and Central Texas regions, the chance for rain will decrease to 20-30 percent Monday through Wednesday as an area of tropical moisture lingers over the area.  Additional totals to around a half inch will be possible.  Expect a partly cloudy sky.

Longer-range solutions call for a slight chance for mainly afternoon showers late next week into next weekend as considerable tropical moisture spreads north from the Gulf. 

High temperatures are forecast to be in the middle 80s this weekend, warming to around 90-92 degrees Monday through Wednesday.  Low to middle 90s are forecast late week into next weekend.

Tropical Weather Update

The tropical Atlantic and Pacific are currently quite active.  At the current time, there are no identified threats to the Gulf of Mexico or the Texas coast.  However, we will need to keep a close watch on the disturbance currently located over the east-central tropical Atlantic.  Forecast solutions call for this system to track generally to the west over the next 5-7 days, possibly reaching the Caribbean region by the middle of next week.

Tropical  Storm Florence:  At 10 am CDT, the center of Tropical Storm Florence was located over the central tropical Atlantic, about 935 miles east-southeast of Bermuda.    Florence is moving toward the west near 8 mph and this general motion is expected to continue through Sunday.  A west-northwestward motion with an increase in forward speed is forecast over the southwestern Atlantic Ocean early next week.  Maximum sustained winds are near 65 mph (with higher gusts.  Little change in intensity is expected during the next day or so, but re-strengthening is forecast over the weekend.  Florence could become a hurricane again by Saturday night or Sunday.  Florence could pose a threat to much of the US East Coast around the middle of next week.

Forecasters are closely monitoring a tropical wave with a well-defined circulation located about 700 miles west of the Cabo Verde Islands.  Forecasters note this system's associated shower and thunderstorm activity has not been sufficiently organized to designate the system as a tropical depression.  However, only a slight increase in organization would cause this system to be designated as a tropical depression.  This low is expected to move slowly westward across the tropical Atlantic Ocean  during the next several days.  NHC forecasters are giving this system a 90 percent chance for tropical development over the next 5 days.

Hurricane Center forecasters are also keeping an eye on a second area of disturbed weather over the far eastern Atlantic, about 440 miles east-southeast of the southernmost Cabo Verde Islands.  The system is moving toward the west near 10 mph.  A westward to west-northwestward motion with a gradual increase in forward speed is expected during the next 72 hours. On the forecast track, the disturbance is expected to move near the southern Cabo Verde Islands on Sunday.  Maximum sustained winds are near 35 mph with higher gusts.  Satellite imagery indicates that the disturbance is becoming better organized, and it is expected to become a tropical depression or tropical storm later today.  This system is being designated as Potential Tropical Cyclone 8.

 

RAMMB-CIRA 09/07/18 11:30 am CDT

In the central tropical Pacific, Major Hurricane Olivia was centered about 1465 miles east of Hilo, Hawaii. Olivia is moving toward the west-northwest near 16 mph, and this general motion is forecast to continue through Saturday.  A gradual turn toward the west is expected Saturday night or Sunday.  Maximum sustained winds have decreased to near 115 mph with higher gusts.  Olivia is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale.  A slow weakening trend is expected during the next few days.  The National Hurricane Center's 5-day forecast calls for Olivia to weaken to a tropical storm early next week, but the system could move close to or through the Hawaiian Islands around the middle of next week.
 


Four Bright Planets Still Visible

Four bright planets still shine during twilight, though one is getting very low and tricky. From right to left, they are Venus very low in the west-southwest, Jupiter upper left of Venus, Saturn higher in the south, and Mars well to the left of Saturn.  The best viewing time that includes Venus is around 30 to 40 minutes after sunset.

Have a good weekend.

Bob
 

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A rainy pattern developed across the region over the holiday weekend as the persistent ridge of high pressure moved away from Texas and abundant tropical moisture spread north from the Gulf of Mexico.  The heaviest and most widespread rain over the past 3 days has occurred over the Hill Country, where most totals have averaged between 1 and 2 inches.  Totals were generally less and more spotty across Central Texas where amounts ranged from a quarter inch, to around an inch.  A few spots across Bastrop, Lee and Washington Counties received zero rain.  Meanwhile, an LCRA gauge located in central Hays County, Dripping Springs 5 SSW, recorded 5.01 inches.  Towards the coast, totals generally averaged around a half inch across Colorado and Wharton Counties.  Matagorda County saw widespread totals of 2-4 inches.

NWS Estimated Rain Falling between 3 pm Saturday and 3 pm Tuesday:


Tuesday's weather maps showed a broad trough of low pressure over the Desert Southwest and the southern Rockies.  The ridge of high pressure which had been over Texas last week is now situated over the eastern and northeastern US.  Circulation around the western trough and the eastern ridge has pulled abundant moisture into Texas out of the Gulf of Mexico, resulting in a very moist atmosphere.  Weak disturbances moving through the western trough and pushing inland off the Gulf of Mexico have been responsible for the recent rain and thunderstorm activity.  One other feature of note is tropical storm Gordon, which was centered Tuesday morning over the north central Gulf of Mexico.  Gordon is forecast to push inland tonight across the central Gulf coast, just to the east of New Orleans.  The remnants of Gordon are forecast to spread northwest across Louisiana and Mississippi Wednesday, moving into Arkansas on Thursday.  From here, Gordon's remnants are forecast to turn north to the Plains states late week into the weekend, having no impact on Central Texas.

A mostly cloudy, wet and unsettled weather pattern is forecast to remain in place across Central and South Texas this week as the current moist and tropical air mass holds in place across the region.  The high pressure ridge along the East Coast is not expected to move back across Texas.  Weak disturbances pushing inland off the Gulf, combined with weak disturbances moving northwest out of northern Mexico will cause a daily chance for rain across the entire region today through Friday.  The probability for rain will generally be 40-50 percent.  The most favorable period for rain looks to be from late morning through late evening.  Daily rain amounts are forecast to generally average between 0.25 and 0.5 inches, with isolated totals of 1-2 inches possible.  The sky is forecast to remain mostly cloudy throughout the week, keeping high temperatures mostly in the low 90s.

The chance for rain and thunderstorms is forecast to increase across the northern Hill Country late Friday and across the rest of the region Friday night into Saturday when a weak cold front sags south out of Oklahoma.  The front is forecast to slow down and stall across Central Texas Saturday afternoon into Saturday night.  A widespread shield of rain is forecast along and behind the cold front Saturday.  This area of widespread rain is predicted to weaken and push south of the region Sunday, with a slight chance for rain lingering Sunday afternoon.  High temperatures this weekend are forecast to continue in the low 90s.

Rain totals over the next 7 days are forecast to be significant.  The National Weather Service is calling for totals of 2-4 inches across the Hill Country, extending east to the Interstate 35 corridor.  Totals of 1-2 inches are forecast for areas to the east of Interstate 35.  Keep in mind that due to the tropical nature of the atmosphere, some higher totals will be will possible at a few locations.

NWS rainfall forecast for the period 7 am Tuesday through 7 am next Tuesday:


The outlook for next week calls for a somewhat drier pattern as the tropical air mass weakens.  A slight chance for mainly afternoon and evening rain showers and thunderstorms is forecast throughout the week.  With a weak ridge of high pressure spreading over the area, high temperatures are predicted to be in the middle 90s.   

Tropical Weather Update

The tropical Atlantic has come alive, with two named systems and the potential for a third system soon.

Tropical Storm Gordon

… A Hurricane Warning is in effect from the Mouth of the Pearl River to the Alabama-Florida Border…

At 4 PM CDT, the center of Tropical Storm Gordon was located by NOAA Doppler weather radars over the north central Gulf of Mexico, about 95 miles south of Biloxi, Mississippi.   Gordon is moving toward the northwest near 15 mph and this general motion is expected to continue until landfall occurs tonight along the north-central Gulf coast.  A northwestward motion with some decrease in forward speed is expected after landfall, with a gradual turn toward the north-northwest and north forecast to occur on Friday.  On the forecast track, the center of Gordon will make landfall along the north-central Gulf Coast within the hurricane warning area this evening or tonight, and then move inland over the lower Mississippi Valley through Wednesday.

Data from NOAA Doppler weather radars indicate that maximum sustained winds have increased to near 70 mph with higher gusts.  Some additional strengthening is still possible, and Gordon could become a hurricane before landfall occurs along the north-central Gulf Coast this evening.  Rapid weakening is forecast after Gordon moves inland.

Hurricane Florence

…Florence becomes the third hurricane of the Atlantic season and poses no threat to land through the upcoming weekend…

At 4 pm CDT , the center of Hurricane Florence was located over the central tropical Atlantic, roughly 1305 miles east of the northern Leeward Islands.  Florence is moving toward the west-northwest near 12 mph, and this motion is expected to continue through Wednesday night.  A northwestward motion is expected to begin by Thursday with Florence's forward speed decreasing by the weekend.  Maximum sustained winds have increased to near 85 mph with higher gusts.  Some additional strengthening is possible through tonight, but Florence is expected to weaken beginning on Wednesday and continuing through Friday.

A New Tropical Disturbance

National Hurricane Center forecasters are closely monitoring a broad low pressure system located a few hundred miles south of the Cabo Verde Islands.  This system is forecast to move slowly westward to

west-northwestward across the eastern tropical Atlantic for the next several days.  Environmental conditions are expected to gradually become more conducive for development, and a tropical depression is

likely to form by late this week or this weekend.  NHC forecasters are giving this disturbance an 80 percent chance for development over the next 5 days.

RAMMB-CIRA 09/04/18  11:15 am CDT 

Bob

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