textproduct: Columbia

WHAT HAS CHANGED

Confidence is increasing in wedge conditions developing early next week and a significant warm up with unsettled weather late in the week.

KEY MESSAGES

1. Significant temperature swing expected Sun/Mon as wedge conditions redevelop.

2. Well above normal temperatures and unsettled weather late week.

DISCUSSION

KEY MESSAGE #1: Significant temperature swing expected Sun/Mon as wedge conditions redevelop.

A weak upper trough axis will be slow to move through the region today but will shift east of the forecast area by Sunday with zonal westerly 500mb flow expected. A low level northwesterly flow at 850mb will develop providing some downsloping flow along with 850mb temperature anomalies around 5-7 degrees above normal resulting in high temperatures on Sunday in the 70s to near 80 degrees.

Strong confluent 500mb flow across the Great Lakes into New England Sunday night will drive a backdoor front southward through the forecast area setting up favorable conditions for at least in situ wedging if not a cold air damming scenario into early next week. The extent of cloud cover remains uncertain as upper flow is more westerly than southwesterly atop the northeasterly low level near surface winds. A negative factor for sustaining a strong wedge is that it doesn't appear there will be much precipitation across the area Mon/Tue with most of it staying just to our north across NC/VA where shortwave energy tracks through the westerly flow aloft. Cannot rule out some light precipitation across the northern Midlands but chances remain low at this time. Nevertheless expect temperatures to be below normal each day with highs ranging from the low to mid 50s northern and western Midlands to low to mid 60s southern Midlands and CSRA.

KEY MESSAGE #2: Well above normal temperatures and unsettled weather late week.

A deep upper trough moving into the central Plains by Wednesday will result in downstream upper ridging over the Carolinas and southeastern states with surface high pressure shifting offshore resulting in a warm southerly flow. A deeper trough digs into the four corner region on Thursday and then into the Plains by Friday keeping the upper ridging over our area through the end of the week. NAEFS is showing strong warm temperature anomalies with values above the 90th percentile at all levels from 500mb to 1000mb and values up to the 97th percentile at 850mb by Friday. This should result in temperatures well above normal with highs well into the 70s and lower 80s for the back half of next week. In addition to the warm temperatures, unsettled weather is expected due to increased instability from persistent moisture advection from deep south to southwesterly flow at the surface through 500mb with PWATs approaching 200% of normal late in the week and NAEFS showing PWATs above the 90th percentile. This should result in some diurnal convection across the forecast area. Severe weather does not look like a concern at this time in our area but rather would remain further to the west.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

Widespread IFR to tempo LIFR restrictions continue early this morning with gradual improvement expected through the day.

Low pressure has shifted east of the area with northeasterly flow helping to strengthen in situ wedge and thus widespread low clouds which is the predominant restriction, although periods of visibility restrictions will be possible but mostly between 2 to 4 SM. IFR will be predominant for most of the early morning with tempo LIFR possible at all terminals. A shortwave moving through the area today will likely scour out the low level clouds late today, although have generally favored a later time as models typical improve the wedge too quickly but generally do expect improvement to MVFR late this morning, with MVFR ceilings lingering through much of the day. Tonight, clearing skies will lead to a relatively favorable fog setup, although most models favor this occurring after 6z so have not included additional visibility restrictions with this TAF update. Winds will be light and variable, increasing to around 5 knots out of the north later this morning.

EXTENDED AVIATION OUTLOOK...Nightly low ceiling or visibility restrictions will remain possible over the weekend through midweek.

CAE WATCHES/WARNINGS/ADVISORIES

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