textproduct: Columbia

WHAT HAS CHANGED

Adjusted wording in Key Message. Aviation discussion updated for 00z TAF.

KEY MESSAGES

- 1. Scattered storms continue this evening with isolated damaging wind gusts and heavy rain possible. Lingering moisture leading to scattered to widespread afternoon storms Monday through Wednesday.

DISCUSSION

Key Message 1: Scattered storms continue this evening with isolated damaging wind gusts and heavy rain possible. Lingering moisture leading to scattered to widespread afternoon storms Monday through Wednesday.

Scattered strong to marginally severe clusters continue mainly south of the I-20 corridor this evening as PWATs sit between 2-2.20" across the FA. Instability has waned a bit with the loss of heating, but MLCAPE values still sit around 1500 J/kg. DCAPE values have also diminished with the more stable low level profiles as numerous outflow boundaries continue to traverse the FA. Overall, an isolated severe risk should persist for the coming 1-2 hours, but this should diminish into the overnight as any convection likely becomes a bit more elevated. Tonight, isolated to widely scattered showers and a couple storms could still be possible as the mid level low and surface front continue to work into the region, but severe weather is not anticipated with this activity.

On Monday, the front is expected to move through and the mid level low should drop into the region as hires guidance indicates PWAT's approach 2.2 inches. Low level flow becomes increasingly northerly to northeasterly, keeping temperatures a bit cooler and increased cloud cover is expected to limit destabilization. This brings a lower risk for severe weather with more marginal thermodynamics, but a couple strong to marginally severe storms cannot be ruled out during the afternoon/evening as deep layer shear is slightly increased. The bigger risk Monday may be the heavy rainfall risk as scattered to widespread showers and storms move through the area during the day with efficient rain rates, similar to slightly higher than Sunday in this moist airmass. The highest concern will continue to be in areas highlighted today along with areas that received additional significant rainfall today.

Shower and thunderstorms will likely continue Tuesday and Wednesday and ensemble means have been slower to bring in a drier air mass with PWATs generally greater than a standard deviation above normal for at least portions of the area through Wednesday, although drier air likely starts to sneak into the northern area on Wednesday. Cooler air mass generally expected to continue early this week with a recovery expected to normal or slightly above normal temperatures for the second half of the week as the upper ridge centered over the central CONUS begins to shift eastward.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions continue outside of convection, mainly near OGB, this evening. Isolated showers could persist overnight and MVFR ceilings are possible early Monday morning.

Convection is ongoing across the southeastern Midlands this evening, bringing vsby restrictions to OGB. This should continue over the coming 1-2 hours before a PROB30 then is in place across the terminals into the overnight. This is due to the mid level low nearing the region, possibly sparking isolated to widely scattered showers overnight. Winds this evening and overnight are expected to be light, but quite variable with the numerous outflow boundaries in the FA. VFR conditions outside of this activity are expected to persist until around 06-09z, when northeasterly flow behind a weak front and rich low-level moisture act to bring periods of MVFR ceilings into Monday morning. The NBM remains the most aggressive in timing (~06z), but the HRRR pushes the onset a bit later (~08-10z), so there is still some uncertainty in the exact timing. These ceilings should persist through the morning before gradually lifting to VFR after 15-17z with a BKN cumulus deck likely remaining. Winds should pick up out of the northeast around 5-7 kts during the late morning as well. During the afternoon, another round of scattered to widespread showers and storms are expected where associated restrictions will be possible. This activity is expected to persist through the end of the TAF period.

EXTENDED AVIATION OUTLOOK...A good chance for afternoon showers and thunderstorms with associated restrictions is expected through at least Tuesday.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.