Area Hydrologic Discussion
— Latest
Threat
POTENTIAL IMPACTS: Flash and urban flooding possible WHERE: Maryland into Southeast New York WHEN: Through this evening
Rainfall & Conditions
QPF: 2 - 4", locally higher (HRRR/WPC) QPE: Up to 1" with locally higher amounts (MRMS 6 hours) Rates: 1 - 2"+ (MRMS,HRRR) Soils: Variable Streamflows: Variable (Observed, USGS)
Discussion
Rounds of rainfall will continue to impact portions of the northeast through the evening. Some areas have already received 1 - 2" of rainfall resulting in flooding impacts and more saturated soils. With more rainfall forecast, additional flash and urban flooding impacts will be possible. Antecedent conditions are a mixed bag with conditions on the drier side in the southern portions of the area of concern and near normal to the north. These drier conditions to the south may initially mitigate flood impacts, however, given the potential for training, the flood potential will increase across this southern region going through the evening as well.
The HRRR-forced National Water Model (NWM) has been showing more organized responses over the last several runs with probabilities for rapid-onset flooding (ROF) ranging up to 50% (shown right) suggesting some remaining uncertainty in where the heaviest rainfall will materialize. The magnitude of the responses haATLve shown consistent isolated but robust rises across the area; however, the signals have tended to shift from run to run suggesting uncertainty with the placement. Given these factors, flash and urban flooding will continue to be possible through the evening, particularly in widespread urban areas.
Addressed To
WFO: ALY, OKX, CTP, LWX, PHI RFC: RHA, TAR, WPC
000 AGUS74 KWCO 271800 AHDNWC Area Hydrological Discussion #196 - EXPERIMENTAL NWS National Water Center - Tuscaloosa, AL 1241 PM CDT Thu Aug 27 2026 POTENTIAL IMPACTS: Flash and urban flooding possible WHERE: Maryland into Southeast New York WHEN: Through this evening FORECAST RAINFALL AND ANTECEDENT CONDITIONS: QPF: 2 - 4", locally higher (HRRR/WPC) QPE: Up to 1" with locally higher amounts (MRMS 6 hours) Rates: 1 - 2"+ (MRMS,HRRR) Soils: Variable Streamflows: Variable (Observed, USGS) DISCUSSION: Rounds of rainfall will continue to impact portions of the northeast through the evening. Some areas have already received 1 - 2" of rainfall resulting in flooding impacts and more saturated soils. With more rainfall forecast, additional flash and urban flooding impacts will be possible. Antecedent conditions are a mixed bag with conditions on the drier side in the southern portions of the area of concern and near normal to the north. These drier conditions to the south may initially mitigate flood impacts, however, given the potential for training, the flood potential will increase across this southern region going through the evening as well. The HRRR-forced National Water Model (NWM) has been showing more organized responses over the last several runs with probabilities for rapid-onset flooding (ROF) ranging up to 50% (shown right) suggesting some remaining uncertainty in where the heaviest rainfall will materialize. The magnitude of the responses haATLve shown consistent isolated but robust rises across the area; however, the signals have tended to shift from run to run suggesting uncertainty with the placement. Given these factors, flash and urban flooding will continue to be possible through the evening, particularly in widespread urban areas. GRAPHICAL REPRESENTATION: weather.gov/owp/operations-ahd Additional National Water Center products are available at: weather.gov/owp/operations //Smith ATTN...WFO...ALY...OKX...CTP...LWX...PHI ATTN...RFC...RHA...TAR...WPC