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190812-

PROBABILISTIC HYDROLOGIC OUTLOOK

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON, TX

312 PM CDT Thu Apr 18 2024



...Advanced Hydrologic Prediction Service (AHPS) long range

probabilistic outlook for Harris County Watersheds in Southeast Texas...





The Houston/Galveston National Weather Service Office has

implemented Advanced Hydrologic Prediction Service (AHPS) for Harris

County Watersheds in Southeast Texas. AHPS enables the National Weather

Service to provide long-range probabilistic outlooks. This service is

also available on the internet.





In the table below, the 90 through 10 percent columns indicate the

chance the river could rise above the listed stage levels in the

next 90 days. Example: Greens Bayou at U.S.Hwy 59 in Houston has a flood

stage of 55 feet. There is a 50 percent chance the U.S. Hwy 59 forecast

point will rise above 49.0 feet during the next 90 days.





           Chance of exceeding stages at specific locations

                  Valid 04/17/2024 - 07/16/2024





Location       fs(ft)   90%  80%  70%  60%  50%  40%  30%  20%  10%

-------------------------------------------------------------------

Spring Creek

 Tomball       155.0    140.7 143.9 145.8 146.3 147.4 148.7 150.0 151.2 153.7

Cypress Creek

 Katy-Hockley  157.3    146.4 147.2 149.7 150.8 152.2 153.3 154.3 155.4 158.9

 Grant Road    122.0    104.5 106.2 107.0 108.6 110.6 114.9 116.9 119.1 123.0

Greens Bayou

 Knobcrest St   84.8    69.8 70.7 71.4 71.9 72.6 73.5 73.9 75.5 77.8

 U.S. Hwy 59    55.0    43.6 45.1 46.5 47.0 49.0 50.0 50.7 53.6 55.2

 Ley Road       30.0     6.4  8.6  9.6 11.4 13.3 14.8 23.2 25.8 28.2

White Oak Bayou

 Heights Blvd   32.0    13.5 14.5 15.9 17.2 18.3 19.3 21.5 25.1 30.2

Brays Bayou

 Main Street    41.0    23.8 25.4 27.3 28.6 29.4 30.6 32.5 36.0 40.3

Buffalo Bayou

 West Belt      62.2    41.8 42.4 42.6 43.0 43.2 43.6 44.2 45.1 46.1

 Piney Point    52.0    34.5 35.6 36.3 36.8 37.6 38.0 38.3 39.6 40.4

 Shepherd Dr    28.0     8.0  9.0 10.3 11.5 12.1 12.5 13.9 17.6 22.5





This long-range probabilistic outlook contains numbers that are

calculated using multiple scenarios from 50 years of historical

climatological and stream flow data. These numbers also take

into account current conditions of the river and soil moisture.

By providing the complete range of probabilistic numbers, the

level of risk associated with long-range planning decisions can

be determined.





Additional supportive data and explanation are available on the

internet at: https://water.weather.gov/ahps2/long_range.php?wfo=hgx

(internet address is all lower case).





Long-range probabilistic outlooks are issued around the third

Thursday of every month.





$$