textproduct: NWS Birmingham

KEY MESSAGES

Issued at 1238 AM CDT MON MAY 25 2026

- There is a medium risk of flash flooding today and Tuesday, especially in urban and other poor drainage areas. Rainfall amounts of 1 to 2 inches are expected with locally higher 3 to 4 inch amounts.

- A low risk remains for strong thunderstorms with gusty winds this afternoon.

- Patchy dense fog will develop early this morning. Use caution while driving.

DISCUSSION

(Today through Sunday) Issued at 1202 AM CDT MON MAY 25 2026

Little change in the weather pattern is expected Monday and Tuesday as a broad upper low over the ArkLaTex becomes trapped underneath a building ridge over the central portions of North America. Deep layer southerly to southwesterly flow between this feature and a strong subtropical ridge over the western Atlantic will continue to funnel deep tropical-like moisture into Central Alabama, while several embedded vorticity maxima/MCVs emanating from convection over the Gulf provide forcing for ascent. First off, recent rainfall and some patches of clear skies are currently resulting in patchy dense fog developing. Widespread dense fog development remains uncertain given increasing low to mid level clouds expected later in the night, but the newest HREF probabilities for dense fog have increased. We will monitor the need for a dense fog advisory for portions of the area overnight. Similar to previous days, we expect some additional shower development in our southwest counties in the early morning hours. Then showers and storms will increase in coverage and lift northward through the morning hours and continuing into the afternoon, with outflows eventually propagating further east where the higher instability will be. There will continue to be around 20-25 kts of 0-6km bulk shear resulting in some loosely organized multicells with gusty winds. However, mid-level lapse rates will continue to be weak in the tropical-like air mass with saturated profiles. Water loading will be a limiting factor for strong updrafts, and with a lack of stronger updrafts that should limit for the stronger downdrafts and associated downbursts/microbursts. Therefore similar to Sunday the severe weather potential is nonzero but very low.

Locally heavy rainfall and isolated to scattered flash flooding continues to be the main concern. Storms will be moving but the unidirectional flow will allow for some training, with favorable upper-level divergence in the right entrance region of an upper- level jet streak. High PWATs and deep warm cloud layers will also be favorable for efficient rainfall rates. Limiting factors will be the modest 850mb moisture transport, and modest instability which could limit heavier rainfall rates. Still, the USGS National Water Dashboard indicates streamflows running above normal to well above normal along the I-65 corridor and in southwestern portions of Central Alabama, while still running below to well below normal in southeastern and east-central portions of Central Alabama. The placement and magnitude of the heavier bands of rainfall remain uncertain, but given the recent rainfall and some HREF members indicating some 4+ inch amounts, we have issued a Flood Watch for today and Tuesday covering where the best overlap of heavy rainfall potential and lower flash guidance appears to be.

By Wednesday the upper low will have opened up into a wave and weakened, and the ridge to our east will build westward a bit. Still, southerly flow and a moist air mass will remain in place through Saturday, resulting in continued high rain chances, with some weak troughing undercutting the building ridge over the north-central CONUS by later in the week. Some additional heavy rainfall concerns may develop by then. By the weekend an omega block is expected to develop over central Canada. The downstream trough over the northeast CONUS will eventually cause a transition to northwest flow aloft, and also cause a back door cold front to potentially approach the area. How far this front and associated drier air behind it makes it is uncertain.

32/JDavis

AVIATION

(06Z TAFS) Issued at 1238 AM CDT MON MAY 25 2026

Low level moisture will remain high with flow from the south bringing plenty of moist air from the Gulf. With light winds and recent rain, IFR to LIFR ceilings are expected at each TAF site tonight, with variability on timing of when these ceilings will reach each TAF site. Otherwise, fog development is likely, with visibilities also dropping at each TAF site. Confidence is low on timing at this time. Low ceilings will remain through much of the morning, improving slightly by mid day, with scattered convection developing and moving through the state through the afternoon and early evening on Memorial Day. Any storm will likely drop visibilities to LIFR briefly. Due to uncertainty in timing and coverage, have left a PROB30 to show a trend of when thunder will be most likely.

24

FIRE WEATHER

A persistent weather pattern will produce scattered to numerous showers and thunderstorms each day this week. As a result, there are no fire weather concerns.

PRELIMINARY POINT TEMPS/POPS

Gadsden 80 66 80 65 / 80 80 90 50 Anniston 79 67 80 66 / 90 70 90 50 Birmingham 79 67 80 67 / 90 70 90 50 Tuscaloosa 80 69 81 69 / 90 60 80 50 Calera 80 67 81 67 / 90 60 90 50 Auburn 79 69 80 68 / 90 60 80 50 Montgomery 79 69 80 68 / 90 70 90 30 Troy 80 69 81 68 / 90 60 90 30

BMX WATCHES/WARNINGS/ADVISORIES

Flood Watch from 10 AM CDT this morning through Tuesday evening for the following counties: Autauga-Bibb-Blount-Calhoun-Cherokee- Chilton-Clay-Cleburne-Coosa-Dallas-Elmore-Etowah-Hale-Jefferson- Lowndes-Marengo-Montgomery-Perry-Randolph-Shelby-St. Clair- Talladega-Tuscaloosa-Walker.