textproduct: Columbia

SYNOPSIS

After a foggy start to the week on Monday, dry weather is expected through much of the week ahead with a notable warming trend and well above average temps. The next chance of rain and cooler temps arrives late Thursday into Friday.

NEAR TERM /UNTIL 7 AM MONDAY MORNING/

Key message(s):

- Another round of dense fog is looking more likely tonight.

With clearing, or mostly clear, skies across the area, guidance continues to trend towards fog quickly building back in after midnight tonight again. While there is some cirrus aloft downstream of the strong ridge axis, dew point depressions and are already small (between 2-6 degrees) and crossover temps are in the mid-40's. So we will not need ideal cooling to produce a favorable fog setup. Some MOS guidance is very aggressive with fog tonight, and hi-res guidance like the HRRR and RRFS remain aggressive with this outcome as well. Should this pan out, another Dense Fog Advisory is likely for more of the area and for a longer period of time tonight with widespread 1/4 mile or less visibilities into Monday morning. Thankfully, it looks like low temperatures should remain in the mid to upper 30s tonight, which will help us avoid any freezing fog problems.

SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/

Key message(s):

- Generally with near normal temperatures expected.

Upper level northwesterly flow should transition to a more zonal westerly flow on Monday as a strong shortwave and associated surface low move across the Great Lakes region. At the surface high pressure will be offshore allowing for a return southwesterly flow across the area which should support warmer temperatures on Monday with highs expected in the 60s. Expecting another morning with possible widespread fog across the area on Monday with low level moisture trapped beneath mid level dry air with light boundary layer winds.

Tuesday figures to be a bit warmer than Monday with another day of southwesterly flow and warm advection in response to the surface low tracking through the Great Lakes region with highs expected to be in the upper 60s to lower 70s. Some guidance is suggesting possible light showers moving into the CSRA Tuesday night just ahead of the approaching frontal boundary with PWATs approaching an inch (nearly 150 percent of normal) but with minimal forcing it appears unlikely, although non-zero. Above normal lows expected both Monday and Tuesday night with Tuesday night being well above normal with lows in the lower 50s with increased clouds and wind due to an increased pressure gradient.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Key message(s):

- Warm above normal temperatures expected - Increasing rain chances Friday into the Weekend

Ensembles continue to favor a transition to broad upper level ridging along the East Coast during mid to late week in response to upper troughing across the west. Increasingly deep southwesterly flow will result in a warming trend in temperatures with high and low temperatures expected to be above normal. ECMWF EFI trends have also been showing increasing confidence in well above normal temperatures (10-15 degrees) during this period. High temperatures are expected to be in the 70s from Wednesday into Saturday with lows in the upper 40s to lower 50s.

Dry weather is expected Wednesday and Thursday under the influence of upper ridging despite ensembles indicating increasing atmospheric moisture with PWATs rising to around 200 percent of normal by Friday. Ensembles continues to be in agreement with the overall upper pattern shifting the upper ridge axis east of the area by Friday with upper troughing moving eastward into the OH/MS valleys over the weekend. There remain significant differences in the details of the operational models handling the phasing of southern and northern stream energy leading to lower confidence on timing of increased chances of rain. However, it does continue to look like chances of rain for the forecast area are highest on Friday and Saturday as the approaching upper trough pushes a cold front toward the forecast area.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Another round of lifr conditions in fog/stratus is expected to develop once again tonight.

Taf sites starting off with basically vfr conditions. Skies are clear, visibilities mostly unrestricted, and winds are light to calm. There remains a good amount of low-level moisture across the region, and cross-over temperatures are in the mid 40s, close to what surface temperatures will be dropping into over the next several hours. Guidance has been consistent with once again developing another round of widespread fog, dense at times, late tonight and into Monday morning. This will bring ifr/lifr visibilities and clouds to all taf locations late tonight. Have begun bringing mvfr restrictions into tafs after midnight, with rapidly deteriorating visibilities into ifr/lifr by 08z at all sites. Those conditions should then persist through 14z Monday once mixing begins. Do bring improvements back to potential vfr between 14z-15z, but would not be surprised if low clouds end up holding in on a little longer similar to what happened this Sunday morning.

EXTENDED AVIATION OUTLOOK... No significant aviation hazards are currently anticipated through Friday.

CAE WATCHES/WARNINGS/ADVISORIES

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