textproduct: Columbia

WHAT HAS CHANGED

Little change in the expectation of a gradual warming trend this week. It will be dry through mid-week, then rain chances start to increase again closer to the weekend. Aviation discussion updated.

KEY MESSAGES

- 1) A warming trend this week will lead to well above normal temperatures, especially Wednesday through Friday.

- 2) Rain chances look to increase again late this week or this weekend.

DISCUSSION

KEY MESSAGE #1: A warming trend this week will lead to well above normal temperatures, especially Wednesday through Friday.

LREF 500 mb height interquartile range remains less than 3 dam through Thursday, indicating good ensemble agreement in the overall synoptic pattern. Given this pattern features surface high pressure offshore and strong upper ridging for this period, confidence is high for a period of well above normal to near record high temperatures. LREF max T interquartile ranges are between 1 and 4 degrees for CAE through Thursday, and only slightly greater at 5 degrees on Friday. NBM temperatures show highs reaching around 70 by Tuesday, then increasing by 2 or 3 degrees each afternoon through Friday. Record highs by the end of the week are generally in the low 80s, and NBM probabilities of 80 degrees or higher are notably 50% to 75% southeast of I-20 on Friday. Lower confidence in temperatures returns by the weekend with the potential for rain chances increasing and the upper ridge breaking down.

KEY MESSAGE #2: Rain chances look to increase again late this week or this weekend.

The overall synoptic pattern depicted by the global ensembles suggests the next decent shot of rain to be late this week or perhaps this weekend. Deterministic solutions have been inconsistent over the last several runs, so have little confidence that we'll see much if any precip around the middle of the week, especially given a lack of forcing and persistent upper ridging. There may be a bit more potential by Thursday as a weak frontal boundary tries to sink into the northern forecast area, and PW values will be slightly higher by then as well. However, a more significant pattern shift in the way of an upper trough and preceding deeper southwest flow aloft appears most likely toward the upcoming weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Widespread restrictions continue through at least 08-10z before VFR conditions return later this morning.

Widespread IFR ceiling restrictions are now seen at all TAF sites as rain clears the area with a front working through and 7-10 kt winds shifting out of the northwest. These restrictions continue much of the night until around 08-10z when downsloping flow helps scour out these low clouds and bring a return to VFR conditions, but brief periods of MVFR ceilings cannot be ruled out. OGB may linger in MVFR ceilings a bit later into the morning before returning to VFR. Guidance is hinting that a 35-40 kt LLJ will set up between 09-13z as the system clears, strongest along and north of the I-20 corridor. Due to this, mention of LLWS was added to the TAF for the Columbia and Augusta terminals as the likelihood of near 40 kts of flow around 2000 ft is highest here. Winds shift out of the north to northeast through the morning and as mixing occurs after 14z, some gusts upwards of 20 kts may mix down to the surface before winds relax into the afternoon and evening with VFR conditions continuing through the remainder of period.

EXTENDED AVIATION OUTLOOK...VFR conditions expected much of the extended period outside of potential fog Tuesday morning.

CAE WATCHES/WARNINGS/ADVISORIES

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