ticka1
07-13-2007, 10:12 AM
Threat for heavy rainfall and flash flooding will return this weekend into next week.
The latest from JeffL:
After a small break from the heavy rains that have soaked that state the last month the upper pattern will once again unfold into a similar one to that of last week where excessive rains will be possible. Stout upper ridge over S TX will break down allowing yet another trough axis to develop over the state between upper highs to the west and east. Models are in good agreement with an upper level low forming within this trough axis and residing across the state through the middle of next week.
Upper level subsidence will give way to large scale rising motions by Sunday supporting complexes of thunderstorms with excessive rainfall. Much concern is had with potential outflow boundaries and weak frontal boundary over N TX as we did not have such well defined boundaries last week and rainfall was still very high. Well defined boundaries can help to focus the rainfall over a certain area for an extended period of time resulting in very high totals and flash flooding. No point in attempting to determine at this time period where such boundaries may reside and where the greatest threat may be found although it would appear there are equal chances areawide by Sunday. Gulf tape is fairly deep and impressive by Monday suggesting potential for nocturnal core rainfall formation near and to the east of any mid/upper low feature with PWS of 2.1-2.4 inches suggesting air mass will be tropical and rainfall rates extremely high.
Hydro:
All area rivers except the Trinity are in the recession limbs of their hydrographs however most remain above bankfull and several above flood stage. Additional heavy rains will result in slowed recessions and potential for additional rises on area watersheds.
A Flash Flood Watch may be required for parts or all of the area sometime Sunday or Monday.
The latest from JeffL:
After a small break from the heavy rains that have soaked that state the last month the upper pattern will once again unfold into a similar one to that of last week where excessive rains will be possible. Stout upper ridge over S TX will break down allowing yet another trough axis to develop over the state between upper highs to the west and east. Models are in good agreement with an upper level low forming within this trough axis and residing across the state through the middle of next week.
Upper level subsidence will give way to large scale rising motions by Sunday supporting complexes of thunderstorms with excessive rainfall. Much concern is had with potential outflow boundaries and weak frontal boundary over N TX as we did not have such well defined boundaries last week and rainfall was still very high. Well defined boundaries can help to focus the rainfall over a certain area for an extended period of time resulting in very high totals and flash flooding. No point in attempting to determine at this time period where such boundaries may reside and where the greatest threat may be found although it would appear there are equal chances areawide by Sunday. Gulf tape is fairly deep and impressive by Monday suggesting potential for nocturnal core rainfall formation near and to the east of any mid/upper low feature with PWS of 2.1-2.4 inches suggesting air mass will be tropical and rainfall rates extremely high.
Hydro:
All area rivers except the Trinity are in the recession limbs of their hydrographs however most remain above bankfull and several above flood stage. Additional heavy rains will result in slowed recessions and potential for additional rises on area watersheds.
A Flash Flood Watch may be required for parts or all of the area sometime Sunday or Monday.