textproduct: Huntsville

KEY MESSAGES

Updated at 946 AM CDT Thu May 28 2026

- A low-medium (20-50%) coverage of showers and thunderstorms is expected today and tonight, with lightning and locally heavy rainfall/flash flooding the main concerns.

- Medium-high (60-80%) chances for showers and thunderstorms return from Friday through this weekend.

- Chances for showers and thunderstorms will begin to diminish on Monday, with drier conditions expected from Tuesday-Thursday.

NEAR TERM

(Rest of Today and Tonight) Issued at 221 PM CDT Thu May 28 2026

There have been no significant changes to near term forecast reasoning since the update earlier this morning. Thus far, moderate-heavy showers and a few thunderstorms in our general region have been confined to a surface wind shift axis (positioned near the AL-TN border), the higher terrain of northeast AL, and along the northern fringe of more extensive precipitation across central AL (occurring downstream from a remnant MCV over the central Gulf Coast). With time, outflow from each area of convection will likely become consolidated in the portion of the forecast area not receiving precipitation at the moment, generating additional showers and storms that should dissipate between 0-2Z. Although hourly rainfall rates have not yet raised concern for flash flooding, we will need to monitor this carefully over the next several hours due to very slow storm motions. Otherwise, lightning will be the most significant impact.

After a brief period of clearing late this evening, it still appears as if redevelopment of showers and perhaps some thunderstorms will occur in the vicinity of the same wind shift axis between 9-12Z Friday, as SSE flow in the low-levels begins to strengthen to the east of a weak shortwave trough in the Arklatex vicinity. Due to the anticipated increase in mid-level clouds after Midnight, the risk for fog development appear rather low as temperatures slowly fall into the m-u 60s.

Previous Discussion: In the mid/upper-levels, our forecast area remains beneath an area of weak steering currents aloft associated with an amplified ridge extending north-northwestward from a subtropical high (centered across the Greater Antilles) to the Upper MS Valley. A light gradient flow regime will also exist today in the low- levels, as a continental airmass builds into the Great Lakes (in the wake of a deepening low over the northwestern Atlantic) and a weak area of low pressure (initially across eastern OK) opens into a trough as it lifts north-northwestwad into southern KS. Within the locally warm/moist airmass, scattered showers and thunderstorms are expected to initially develop across our region between 16-18Z in the vicinity of a subtle low-level streamline confluence axis induced by high pressure to our north, and should persist through the 0-2Z timeframe before dissipating with the onset of the nocturnal cooling cycle. Afternoon temps in the l-m 80s (coupled with dewpoints ranging from the u60s/NE to m70s/SW) will support MLCAPE in the 1000-1500 J/kg range this afternoon (perhaps a bit higher in portions of the CWFA). However, given lack of notable synoptic scale forcing for ascent and flow throughout the atmospheric column, convective cells will be widely dispersed/unorganized and should exhibit slow/erratic motions. Thus, lightning and locally heavy rainfall/flash flooding will be the greatest concerns.

Overnight, high pressure over the Great Lakes will expand southeastward into the Upper OH Valley/central Appalachians, inducing surface pressure rises from western VA into northern GA. Low-level convergence induced by this process will may result in redevelopment of weak convection shortly before sunrise on Friday morning across portions of east-central and northeast AL, which will should spread slowly northwestward with time as southeasterly steering flow becomes established ahead of a weak shortwave trough across the Arklatex. Lows will be rather mild once again (m-u 60s), with only a limited risk for development of patchy fog late this evening (prior to an increase in clouds after Midnight).

SHORT TERM

(Friday through Saturday night) Issued at 946 AM CDT Thu May 28 2026

Latest short range model guidance suggests that the spatial coverage of rain and thunderstorms will become fairly widespread from the Mid-MS Valley southeastward through the TN Valley and into the southeastern Atlantic Coast on Friday and Friday night. This region will be influenced by subtle low-level confluence (induced by high pressure to our north-northeast and a developing lee trough across eastern CO/western KS), and lower latitudes will also experience a minor increase in deep-layer lift provided by a southern stream trough that will shift eastward across the Lower MS Valley and into the Gulf Coast states. As low/mid-level flow gradually veers to the southwest and strengthens ahead of the trough, there may be a tendency for the axis of most widespread rain and thunderstorms to spread northeastward with time on Friday night, but it is uncertain when this will occur and how much northeastward progression the axis will make, and for this reason we will leave POPs in the 60-80% range for both periods. With the early onset on clouds and precipitation (around or shortly after sunrise tomorrow), CAPE will be lower compared to today. Nevertheless, lightning and heavy rainfall/flash flooding will remain impacts from the stronger convection.

On Saturday, global models indicate that the southern CONUS shortwave trough will begin to accelerate quickly off the southeastern Atlantic Coast as it becomes absorbed in the flow around a sharp northern stream wave digging southeastward across New England. Although gradual height rises and subsidence in the wake of the disturbance may limit redevelopment of showers and thunderstorms later in the afternoon, subtle low-level confluence will be maintained by a reinforcing Canadian high building southward from Ontario into the Great Lakes, and this should be sufficient to force redevelopment of convection as the local airmass destabilizes diurnally. With northwest flow aloft predicted to strengthen by Saturday afternoon, showers and storms should be tracking southeastward at a higher rate of speed, thus reducing the concern for excessive rainfall. Present indications are that a slightly drier airmass will begin to spread into the region from the northeast on Saturday night, allowing for a lower coverage of showers/storms (mainly confined to the early evening hours) and slightly cooler overnight lows in the l-m 60s.

LONG TERM

(Sunday through Wednesday) Issued at 950 PM CDT Wed May 27 2026

As high pressure continues to slowly expand over the northeast Atlantic coast, upper ridging centered over the eastern Plains will stall any significant change in airmass until likely late Monday or Tuesday. We will maintain medium chances for rain and thunderstorms Sunday and Monday with the greatest chances during peak diurnal heating hours. Upper troughing paired with high pressure over the northeast will finally begin to dig south toward Tuesday, bringing a drier airmass to the area and a break from the wet and humid pattern we have been in lately. Only low chance PoPs are forecast on Tuesday with the majority of the area expected to stay dry. Temperatures will stay close to seasonable norms during this period, topping out in the upper 70s/lower 80s each day.

AVIATION

(18Z TAFS) Issued at 1216 PM CDT Thu May 28 2026

Prevailing conditions will remain VFR at the HSV/MSL terminals for much of the period. However, local radar data indicates that SHRA are currently developing in the higher terrain of northeast AL, as well as in the vicinity of a low-level convergence axis extending from southern Middle TN into northeast AL (with a somewhat greater concentration across central AL). Current thinking is that coverage of TSRA will increase throughout the aftn, with greatest risk for impacts at the terminals btwn 21-1Z (when AWWs for lightning may be required). After a brief window of partial clearing this evening (when patchy BR/FG may develop), bkn-ovc mid-level clouds will return by 8Z, with redevelopment of SHRA and perhaps some TSRA anticipated in the 10-14Z timeframe. Low-level flow will veer to SW by the end of the period, with MVFR ceilings in low stratus prevalent and perhaps redevelopment of additional SHRA/TSRA btwn 16-18Z.

HUN WATCHES/WARNINGS/ADVISORIES

AL...None. TN...None.