textproduct: Columbia

WHAT HAS CHANGED

Temperatures trending warmer to end the week above normal with increasing chances of rain over the weekend. Aviation discussion updated for 18z TAF.

KEY MESSAGES

- 1. Generally low chances of rain through Friday favoring the CSRA with a warming trend expected across the area.

- 2. Increased chances of rain over the weekend with highest chances on Sunday into Monday.

DISCUSSION

Key Message 1: Generally low chances of rain through Friday favoring the CSRA with a warming trend expected across the area.

Much drier air noted across North Carolina on WV imagery and seen in satellite derived PWATs with values at or below 1 inch over much of NC. A sharp gradient to values to over 2 inches noted over South Carolina especially south of the I-26 corridor. Some convection already ongoing in the CSRA along a weak low level convergence zone but really struggling beneath the upper ridge. Expect scattered non severe convection into the evening. Slow storm movement with high PWATs could yield very heavy rainfall in stronger convection. Similar expectations for tomorrow regarding convection although coverage may be even less as some of the drier air to our north works southward.

Temperatures will be warming on Thursday and Friday as the upper ridge axis shifts southeastward from the upper Midwest to the Carolinas. NAEFS shows 850mb temperatures above the 99th percentile both days while the ECMWF also highlights anomalously high max temps to end the week. Expect high temperatures to push back into the mid and upper 90s with Friday being the warmest day. While deep mixing should result in some drier air mixing down to the surface, heat indices are expected to rise back above 100 degrees and could reach 105 by Friday.

Key Message 2: Increased chances of rain over the weekend with highest chances on Sunday into Monday.

Ensemble guidance suggests the upper ridge will retrograde and become re-established over the western CONUS by Saturday with an upper weakness left behind across the deep south and northeastern Gulf. This will allow for troughing across the OH Valley into Mid-Atlantic and New England bringing shortwave energy into the region interacting with above normal PWATs resulting in an increase in chances of convection late weekend into early next week.

There may be a slightly better chance of severe weather on Sunday as well with some increased wind shear and upper forcing from shortwave energy combining with diurnal instability. Also of note, NHC has added a 20% area across the northeastern Gulf for possible tropical development in the next 7 days.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Scattered showers and storms around Augusta, otherwise VFR conditions likely through the period.

The slow moving, southward sinking boundary continues to shift through our area causing a few showers and storms along the Savannah River westward this afternoon. This may bring a few storms into AGS and DNL this afternoon, with enough confidence in terminal impacts for a prob30. The remaining TAF sites will likely remain convection free. Drier air will move in overnight with clearing skies and light winds. Some morning stratus-fog is possible Thursday morning but confidence is quite low with a lack of model agreement. This pattern continues Thursday, but with slightly lower rain chances at AGS and DNL.

EXTENDED AVIATION OUTLOOK...The threat for restrictions eases for the end of the week into the upcoming weekend as conditions begin to dry out. Restrictions from showers and thunderstorms return this weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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