Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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224 FXUS64 KHUN 130245 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 945 PM CDT Sun May 12 2024 ...New NEAR TERM... .NEAR TERM... (Rest of tonight) Issued at 944 PM CDT Sun May 12 2024 A plethora of high clouds have enveloped much of the southeast. These clouds will low fairly quickly overnight. Deeper moisture advection working into the area from our southwest will overrun a weak stalled front overnight. We will likely see some virga around and after midnight. However, the lower levels of the atmosphere will still take a bit longer than that to moisten up enough for any precipitation aloft to reach the ground until closer to daybreak on Monday. Given the moisture advection seen in models that should be maximized in our southwest counties until shortly after midnight and the light or calm winds expected through then, some patchy fog is possible. Expect this to mainly occur towards Cullman county and in northwestern Alabama, where low level moisture advection should be the best. Further east, drier air will make it a bit harder to see fog. Expect overunning precipitation to move northeast into the area just before daybreak as winds pick up to between 5 and 10 mph. No thunderstorms are expected through daybreak today. Nudged up lows a tad into the lower 60s near and west of the I-65 corridor and into the 55 to 60 degree range elsewhere. && .SHORT TERM... (Monday through Tuesday Night) Issued at 240 PM CDT Sun May 12 2024 Rain chances will increase through the day Monday in response to an incoming area of sfc low pressure from our west (over the Central Plains moving into the MS Valley). Ahead of this, a series of upper level shortwaves will allow low-medium chances (30-60%) of showers with a low-medium chance of producing lightning through the afternoon hours Monday. As instability slightly increases Monday night (along with 6.5-7.0 C/km mid level lapse rates and ~40-50 kts of 0-6km shear), there is a low chance some storms may become strong-- bringing threats of gusty to damaging winds and hail. Confidence in strong storms remains low as the warm sector track trends to the south of our area (remaining more in South/Central AL). SPC has placed portions of our CWA (primarily areas south of the TN River) in a Marginal Convective Outlook (risk level 1/5) on Monday into Tuesday. Additionally, model PWATs between 1.3-1.5" would be nearing (just below) the 90th percentile sounding climatology for BMX. Storm total rainfall forecast Monday into Tuesday is between 0.5-1.5". WPC has placed most of our area in a Marginal Excessive Rainfall Outlook (risk level 1/4) for both Monday and Tuesday. This means at least a 5% risk of rainfall exceeding flash flood guidance. Medium-high chances (60-90%) of showers/storms are forecast to continue Tuesday morning through the afternoon hours before subsiding from southwest to northeast in the evening. Temperatures during the short term period will range from the lower to upper 70s for highs with lows in the upper 50s to mid 60s. && .LONG TERM... (Wednesday through Saturday) Issued at 330 AM CDT Sun May 12 2024 An upper level low currently over western Colorado will progress eastward, and should be moving over the eastern Ohio River Valley at the start of this period as a weakening trough. The main surface low should be moving over the VA/MD region, while a weaker low and boundary remain over eastern Tennessee. The presence of this front and remaining moisture will help bring isolated to scattered showers and thunderstorms Wed afternoon for the eastern, and much of the central areas. The area of low pressure and moisture should exit further to the east Wed night, and bringing a brief dry period on Thu. Another system nearing the area from the west will bring more shower and thunderstorm chances starting Thu evening over our far western areas, with the activity overspreading the area overnight Thu and on Fri. Have maintained likely (60-70%) rain chances on Fri. Output from some of the medium range guidance, especially the ECMWF/Canadian were hinting that some of the storms Fri afternoon/evening could become strong, with high outflow winds the main threat. Precipitable water amounts at and above 1.5" at this time could lead to locally heavy rain, with localized flooding a possibility. Despite the passage of a frontal boundary early Sat, residual moisture remaining will help continue showers as we close out the week. Clouds and showers on Wed will keep highs in the mid/upper 70s. A return of more sun early Thu and a southerly flow should help push highs into the lower 80s on Thu. Highs around 80 are expected Fri and Sat. Low temperatures in the mid/upper 50s Wed night will moderate into the 60s Thu and Fri nights. && .AVIATION... (00Z TAFS) Issued at 527 PM CDT Sun May 12 2024 VFR flight weather conditions are expected through 11-14Z before lower ceilings of 015-030agl (MVFR) arrive. A large area of -SHRA and TSRA will move through central AL Monday, with the northern && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....HC LONG TERM....RSB AVIATION...KTW