textproduct: Columbia

WHAT HAS CHANGED

Marginal risk for severe weather this afternoon has shifted a bit further south. Aviation discussion updated for 12Z forecast.

KEY MESSAGES

- 1. Scattered showers and isolated thunderstorms possible into the afternoon.

- 2. Another cold front moves through mid week with rain chances. Otherwise, dry conditions are expected with temperatures warming above normal into next weekend.

DISCUSSION

Key Message 1: Scattered showers and isolated thunderstorms possible into the afternoon.

Convection today has started to fire up but remains near the eastern portions of our CWA. The surface cold front is slowly working through the southern Tennessee Valley as a shortwave extends from northern MO toward the Ark-La-Tex region. Trends have continued to keep PoP's fairly isolated to scattered with mean QPF amounts generally less than 0.10-0.25". With any amounts greater than 0.50" focused mainly along and south of the I-95 corridor. The front will slowly work through the FA into the early evening as PWAT's reach near 1.50", but the greatest moisture looks to be confined closer to the coast. Ensemble paintballs continue to favor better coverage generally along/south of the I-95 corridor, but individual CAM's do suggest isolated storms could be seen closer to the I-20 corridor.

Overall, with the expected lack of coverage, the risk for widespread severe weather remains low, but any robust storms/clusters could bring the risk of damaging wind gusts as DCAPE values between 600-800 J/kg are seen with a weak inverted "v" profile. A couple instances of sub-severe hail cannot be ruled out as well. In the CWA, this risk would be greatest in the southeastern Midlands, but the greatest chance for severe weather is expected closer to the coast. A Marginal (1/5) risk for severe thunderstorms remains, though has shifted a bit southward along a line roughly from Waynesboro to St. Matthews to Florence.

Key Message 2: Another cold front moves through mid week with rain chances. Otherwise, dry conditions are expected with temperatures warming above normal into next weekend.

There is solid ensemble and cluster consensus that by Tuesday this week, a deep trough will begin digging into the Great Lakes region before deepening a bit further into Wednesday as it pushes into the Eastern CONUS. This trough is expected to drive a surface low across the northern Great Lakes with an associated cold front extending southward. This upper support and front is expected to move through the area late on Wednesday into early Thursday. Timing uncertainty remains across the area, but increased rain chances seem possible with this, mainly near the Pee Dee.

Once the shortwave ejects to the east, model guidance is trending toward a large closed upper level low forming over the Mid-Atlatnic on Friday. This may help lower temperatures near normal for a few days with dry conditions. An upper level ridge will then expand over the southeast. Confidence is increasing that temperatures will warm above normal next weekend with highs possibly reaching the 90s.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR conditions are expected through the period at all sites. An isolated storm remains possible at OGB this afternoon.

A cold front is approaching the region this afternoon, with distinctly quiet weather ongoing ahead of it currently. Partly sunny skies have been noted on and off today, with cloud cover remaining VFR at all sites. Some isolated showers or storms are possible primarily at OGB this afternoon but this seems increasingly unlikely. From there, this becomes largely a wind forecast. Winds are expected to veer as the period goes along & become gusty behind the front this evening. First, winds should become northwesterly for a few hours this afternoon. Then this evening, they are forecast to rapidly veer to the northeast and remain that way through tomorrow. Gusts of 15-20 knots are expected between 00z and 06z, subsiding a bit as the front sinks to our south. Clouds are expected to continue hanging around but remaining VFR, with bufkit time/height cross sections showing cloud cover generally staying between 5kft and 10kft.

EXTENDED AVIATION OUTLOOK...Conditions improve Tuesday with mainly VFR expected. Another front with more scattered showers and thunderstorms approaches the terminals Wednesday.

CAE WATCHES/WARNINGS/ADVISORIES

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