As of 5:04pm, Friday, April 28th, 2017, Brian Smith of the National Weather Service office in Little Rock predicts several waves of showers and thunderstorms to affect Arkansas through the weekend. Heavy rainfall is likely, and severe thunderstorms are a possibility.
As waves of showers and thunderstorms move across the state tonight, and Saturday and Sunday, rainfall will be heavy at times. Heavy rain will be the most likely over northern Arkansas, primarily in the Ozark and Ouachita Mountains. Rainfall amounts in excess of six inches are likely, mainly in areas north of a line from Fort Smith to Pocahontas. Localized amounts of eight inches are possible.
The heaviest rainfall is expected late tonight, and again on Saturday and Saturday night. Already in the last few days, heavy rain has fallen over northern and northwest Arkansas, so additional rainfall on nearly saturated ground will yield the threat of flash flooding.
Stages are high on some area rivers, with some locations on the White River and its tributaries already in minor flood. Heavy rainfall will not only prolong the high stages, but is expected to cause minor to moderate flooding in most basins, and major flooding along the White River basin. These rises are expected to be long-term, likely keeping some areas along the White River above flood stage well into May.
Severe thunderstorms are possible through the overnight hours tonight, and again on Saturday afternoon into Sunday in much of Arkansas. This afternoon, a warm front was located from the Ouachita Mountains to northeast Arkansas. This front will slow down, and will eventually stall out. Showers and thunderstorms will develop this evening and into the overnight hours, in the vicinity of and to the north of the front.
To the south of the front, the atmosphere is capped, which is inhibiting thunderstorm development at the time of this writing (430 PM). However, there are a combination of ingredients in the atmosphere that, if and when something does develop, there will be a likelihood of severe thunderstorms.
Through tonight, the greatest potential for severe thunderstorms will be over central and northern Arkansas, mainly north of a DeQueen, to Little Rock, to West Memphis line. Timing-wise, the potential will be highest in the central portion of the state from around 6 PM to midnight, and in northern Arkansas from around 9 PM to 7 AM.
All modes of severe weather are possible. North of the frontal boundary, the greatest severe weather concern will be large hail and damaging winds. Near and a little south of the boundary, the tornado potential will be highest.
There may be a brief lull in showers and storms, before the next round develops during the day Saturday, as a cold front creeps into the state. Showers and thunderstorms will develop out ahead of the front, primarily during the afternoon and into the overnight hours. All portions of the state will carry about the same risk of severe thunderstorms.
On Saturday and Saturday night, large hail and damaging winds are the primary concerns. With the amount of wind shear over the state, tornadoes will also be a concern, especially during the afternoon and early evening hours.
On Sunday, the cold front will move into central and eastern Arkansas, eventually exiting the state late in the day. There will be a risk of severe thunderstorms on Sunday, primarily in areas near and a little west of the Mississippi River.
Rainfall will gradually come to an end around Sunday night.
As always, please continue to monitor the latest information from your Arkansas National Weather Service Forecast Offices and be prepared to take action if a watch or warning is issued for your area.
People in low-lying and poor drainage areas need to monitor the latest weather conditions. This is especially true for those near the banks of rivers and streams. Take all warnings seriously, and be prepared to move to higher ground if necessary.
Storm warnings for the Arkansas River Valley are automatically posted, as soon as they are issued, through the Arkansas River Valley Storm Warnings Facebook page.