textproduct: Columbia

WHAT HAS CHANGED

Updates to aviation section. Better agreement in rain chances moving in on Wednesday as a cold front nears the region.

KEY MESSAGES

- 1) One more chilly night tonight before temperatures warm up beginning tomorrow, continuing into the mid week.

- 2) First rain chance in the extended comes Wednesday and into Thursday before more rain chances may enter late in the week.

DISCUSSION

KEY MESSAGE #1: One more chilly night tonight before temperatures warm up beginning tomorrow, continuing into the mid week.

High pressure remains in the area today with cooler temperatures in place as highs this afternoon stick toward the mid to upper 40s with a couple spots nearing 50. Tonight, some cirrus moving in should limit radiational cooling a bit, but chilly lows into the mid to upper 20s are still expected with southern spots closer to the low to mid 30s. The upper ridge then begins to near the region Monday, moving overhead by Tuesday with 500mb heights exceeding the NAEFS 99th percentile. This strong ridge and low level WAA will allow temperatures to reach near normal on Monday before nearing the 70s on Tuesday. Heading into the remainder of the week, some uncertainty remains for precipitation chances and thus temperatures, but the trend in blended guidance to keep temperatures above normal Wednesday before lowering to near normal during the late week has continued, and this seems reasonable considering greater model confidence in troughing developing over the northeast CONUS.

KEY MESSAGE #2: First rain chance in the extended comes Wednesday and into Thursday before more rain chances may enter late in the week.

Greater agreement is seen across model guidance in the synoptic pattern heading into the mid week before uncertainty remains for the late week period. Recent ensemble and global guidance displays a cutoff low off the western coast of Mexico will gradually be forced eastward as a deep trough moves into the Pacific Northwest, bringing PVA near the FA toward Wednesday. There will also be a surface low moving across Quebec through the day Wednesday, dragging a weak cold front into the region. Ahead of this front and shortwave, PWAT's are expected to reach 150-170% of normal with rain chances moving in sometime Wednesday, possibly continuing into early Thursday as slight timing differences still exist between deterministic guidance. After this, greater variability remains in models in the progression of the deep trough over the western CONUS. There has been a bit more run to run consistency showing this trough moving across the central US with a surface low gradually developing, but generous timing/intensity differences still exist. Due to this confidence in timing remains low but at least slight chance PoP's should exist heading toward the late week and into the weekend as moisture remains in place.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions continue.

Surface high pressure will continue to build into the region, resulting in rather light and variable winds at the terminals through the forecast period. High level clouds continue to spill over the upper ridge axis to the west and stream across parts of the area within a northwest flow aloft. Expect ceilings to lower overnight into Monday morning, although remaining VFR, as an upper disturbance crosses the area.

EXTENDED AVIATION OUTLOOK...No anticipated aviation concerns through early this week. Restrictions possible moving into mid-week as another system pushes into the region and brings rain potential along with it.

CAE WATCHES/WARNINGS/ADVISORIES

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