textproduct: Huntsville

KEY MESSAGES

Updated at 1053 PM CDT Thu Jun 18 2026

- There is a low (10-30%) chance for additional showers and thunderstorms overnight as a weak cold front enters the region. The coverage of showers and storms will be most concentrated south of the TN River tomorrow.

- After a brief period of dry weather late Friday into Saturday morning, additional rounds of rain and thunderstorms are forecast into the long term period with high rain chances Sunday-Monday night.

NEAR TERM

(This Evening through Friday) Issued at 1053 PM CDT Thu Jun 18 2026

The remnants of TC Arthur will continue to accelerate east- northeastward across northern GA this evening and into north- central SC by 12Z Friday, with light stratiform rain along the northwestern periphery of its circulation expected to end in our southeastern zones by 3Z. Meanwhile, a cold front currently extends from the Upper OH Valley southwestward through central KY/western TN to a small low over central AR, before transitioning to a stationary front that extends west-southwestward to a lee cyclone across the southern TX Panhandle. Although showers and thunderstorms occurring in the vicinity of the front have largely dissipated with the onset of the nocturnal cooling cycle, there is some concern that a few convective cells may develop as the leading edge of the slightly drier continental airmass shifts southward and approaches the AL-TN border between 9-12Z. At this point, the risk for thunderstorms appears low (but non-zero with CAPE in the 500-750 J/kg range) and anticipated coverage only appears to warrant a 20-30% POP as the greatest concentration of nocturnal convection should occur across a corridor from south- central KS into northern AR (slightly north of the surface front) where elevated warm advection (related to an amplifying shortwave over IA/MO) will be maximized. Otherwise, overnight lows will be a few degrees cooler tonight (u60s-l70s) due primarily to cooler afternoon temps earlier today, with development of patchy fog/low stratus clouds prior to sunrise.

During the day tomorrow, the center of a modified Canadian anticyclone will build southeastward from the central Plains into the Lower OH Valley, forcing the leading edge of the drier continental airmass further southward through our CWFA. Present indications are that thunderstorms will redevelop in the vicinity of the moisture gradient over the course of the morning, with additional clusters of storms perhaps spreading southeastward from AR beneath NW flow aloft of 25-35 knots. Although it is unclear at this point precisely how far southward the boundary will reach before convective initiation begins, it seems reasonable to advertise a gradient in POPs ranging from 10-20% (north) to 30-40% (south). However, the greatest coverage of storms tomorrow should exist across central/southern portions of AL. With only a light NNW wind and mostly sunny skies north of the front, afternoon highs will be similar compared to today (l-m 80s).

SHORT TERM

(Friday night through Sunday night) Issued at 1053 PM CDT Thu Jun 18 2026

Surface high pressure will continue to spread southeastward into the southern Appalachians on Friday night, with a light northeast wind allowing both air temps and dewpoints to fall into the l-m 60s. Thus, we expect dry conditions (after any afternoon showers and storms dissipate south of the TN River), with patchy fog in a few of our normally fog-prone locations. During the day on Saturday, the stalled boundary to our south will begin to lift northward as a warm front in response to the east-northeastward movement of a mid-level shortwave trough across the Great Basin and subsequent development of a rather impressive surface low across eastern CO. Scattered showers and thunderstorms may develop over the course of the afternoon as the moist airmass begins to return northward, but at this point it appears as if convection will be most concentrated across the southwestern portion of the forecast area (where POPs are in the 20-30% range). As the lee low begins to migrate east-northeastward across KS on Saturday night, low-level SSE flow will gradually strengthen with dewpoints rising into the lower 70s region-wide by Sunday morning. Although a few showers may occur at times, POPs remain rather low and in the 10-20% range.

On Sunday and Sunday night, models suggest that the dominant synoptic surface low will advance further east-northeastward across the Mid-MS Valley and into northern OH (in conjunction with the mid-level shortwave trough). This configuration will induce strengthening southwesterly flow throughout the depth of the tropospheric column across our region, with PWAT values surging back into the 1.8-2" range. A fairly widespread coverage of thunderstorms is expected to evolve over the course of the day from southern MS northeastward into TN/KY (perhaps aided by an MCV from a nocturnal MCS over the MO Valley), but although rich tropical moisture may lead to very high rainfall rates, cells will be moving rather quickly to the northeast in this regime, which should limit concern for flooding. However, due to higher CAPE and stronger low/mid-level flow, storms may be capable of producing more frequent wind gusts in the 40-50 MPH range. Although afternoon convection across the open warm sector will exhibit a weakening trend and should dissipate shortly after sunset, there are indications that a large MCS (perhaps including multiple bowing segments) may evolve in the vicinity of the trailing cold front Sunday evening from eastern KS into western IL. The leading edge of this system may approach our forecast area prior to sunrise on Monday, at which point the WSW low-level jet should be peaking in the 35-40 knot range. Fortunately, forecast soundings suggest that convection may be slightly elevated above a strong low-level inversion, but if this does not materialize, this activity would carry a risk for both severe wind gusts and perhaps a few tornadoes as well.

LONG TERM

(Monday through Thursday) Issued at 1053 PM CDT Thu Jun 18 2026

A high coverage of showers and thunderstorms is expected to continue throughout the day on Monday and into Monday night as a surface low ejects northeastward off the coast of New England and a trailing cold front slips slowly southeastward. Although multiple rounds of convection may ultimately have an impact on instability, forecast soundings indicate a favorable combination of high CAPE and sufficiently strong low/mid-level flow that would be conducive for organized/severe thunderstorms during this timeframe. As for the remainder of the period, there are subtle differences within the suite of guidance regarding how far south the cold front (and a reinforcing surge of drier continental air in its wake) will push before eventually stalling. Due to this uncertainty, we will maintain POPs in the 20-40% range (highest during the afternoon). Fortunately, it appears as if the storm environment for the rest of the week will feature lighter low/mid- level flow and shear (reducing the risk for organized convection). However, lapse rates aloft will remain steep in the west- northwest flow regime, and high CAPE may still yield a risk for locally damaging downburst winds on a daily basis. Temperatures will fluctuate very little throughout the extended period, with highs in the l-m 80s and lows in the m-u 60s.

AVIATION

(00Z TAFS) Issued at 728 PM CDT Thu Jun 18 2026

The remnants of TC Arthur will continue to accelerate east- northeastward across northern GA and into SC overnight, with lingering pockets of light rain expected to end across the southeastern portion of the local area btwn 2-3Z. In the wake of this system, patches of low stratus clouds will persist beneath an overcast layer of Cs, resulting in MVFR cigs as low as 2500 ft AGL. During the early morning hours, a weak cold front will begin to shift southward across the AL-TN border, with weakening flow invof the boundary perhaps supporting development of lgt BR/FG and IFR-level stratus btwn 8-13Z. Although a few SHRA/TSRA may also occur near the wind-shift axis, confidence is not high enough to warrant more than a PROB30 group for this scenario. Light NNW winds will slowly advect a drier continental airmass into the northeastern portion of the forecast area throughout the day tomorrow, with a return to VFR conds expected after 14Z.

HUN WATCHES/WARNINGS/ADVISORIES

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