Page | 1

8 AM August 15, 2015 – River Flooding/Heavy Rain Update

Synopsis/Overview: The forecast for the next several days is for an active summer thunderstorm pattern. There are no well-defined systems or fronts to focus the rainfall, however, moisture levels are high and will result in localized heavy rainfall amounts associated with daily storms. Daily rainfall amounts are likely to vary highly across the area given the scattered nature of the forecast storms. Above normal levels of moisture are forecast to continue through the middle of next week. A persistent low level wind pattern from the south and southeast will favor numerous showers and storms across the western half of the Florida peninsula each afternoon and early evening. Although the greatest coverage of storms each day is likely to be along and inland from the I-75 corridor, the pattern will favor some of these storms moving back to the west toward the coast each day. The pattern and atmospheric conditions through the middle of the week will favor heavy rainfall producing thunderstorms, potentially adding to ongoing flooding and high soil moisture concerns.

NWS Tampa Bay Area Briefing for August 15, 2015

Page 2 of 4

Warnings/Watches/Advisories

River Flood Warnings

o Withlacoochee River at Trilby: Remains in Action Stage. This river is just

below minor flood stage, and will need to be monitored closely if

additional heavy rainfall occurs in the basin this weekend.

o Anclote River at Elfers: Forecast to reach Action Stage Today.

o Cypress Creek at Worthington Gardens: Remains in Minor Flood

o Hillsborough River at Morris Bridge: Remains in Action Stage. This river

is forecast to drop just below action stage tonight, given that additional

heavy rainfall does not fall across the basin today.

o Myakka River at Myakka River State Park: Remains in Minor Flood. This

river is running just below moderate flood stage, and will need to be

monitored closely should additional heavy rainfall occur within the basin

this weekend.

o Horse Creek near Arcadia: Remains in Action Stage

o Peace River at Arcadia: Forecast to reach Action Stage Monday.

The latest forecasts for all local rivers can always be found on the Advanced

Hydrologic Prediction Service (AHPS) Page.

http://water.weather.gov/ahps2/index.php?wfo=tbw

Impacts

Flooding

Widespread areas will see rainfall totals between 0.50” and 1.0” through the weekend, with localized amounts in excess of 2.0” likely. Through the middle of next week, continued above normal moisture and a favorable pattern for thunderstorm development over the western half of the Florida peninsula will lead to widespread areas seeing between 1.25” and 2.5” inches of rainfall. Favorable conditions for heavy rainfall producing thunderstorms will likely result in localized areas seeing in excess of 5.0” of rainfall.

o Focus for the rain, and the greatest coverage of daily storms should generally be along and inland from the I-75 corridor during the afternoon and early evening hours. However, the pattern will favor some of these storms moving back westward toward the coast each day.

o Rivers already at or near flood stage will see prolonged flooding. Showers and Thunderstorms

Gusty thunderstorms could topple shallow-rooted trees due to highly saturated soils.

Isolated strong thunderstorms will produce damaging winds, however the greater threat from thunderstorms the next several days will be the potential for additional heavy rainfall.

NWS Tampa Bay Area Briefing for August 15, 2015

Page 3 of 4

Point and Click Forecast Available For Your City or Zip Code

http://www.srh.noaa.gov/tbw/

Enter City or Zip Code in the upper left box

Total Areal Precipitation Forecast Ending 8PM Sunday

Generally between 0.50” and 1.00”. Locally higher amounts exceeding 2.0” are likely. 1.25”-1.5”

NWS Tampa Bay Area Briefing for August 15, 2015

Page 4 of 4

Total Precipitation Forecast Through 8AM Next Wednesday

Generally 1.25” to 2.50”. Given the favorable pattern for heavy

rainfall producing storms each day, locally higher amounts in excess

of 4.0” are likely.

0.25” – 0.5”