Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
891 FXUS62 KCAE 031846 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 246 PM EDT Wed Jul 3 2024 .SYNOPSIS... Moisture increases through the week and into the weekend with isolated to scattered showers and thunderstorms possible each afternoon. Above normal temperatures are expected and Heat Index values around 110 are possible Friday through Sunday. Atmospheric moisture remains high through the long term supporting a chance of rain each day. && .NEAR TERM /THROUGH TONIGHT/... Key Message(s): - Low-level Moisture increasing tonight Strong upper level ridge extending from southeast TX northeast across the Deep South to SC. At the surface, a pressure ridge centered off the coast of the Mid Atlantic and New England extends into the Carolinas and Georgia. Satellite and observations confirm that drier air remains across the area at the moment with higher moisture confined to the coastal SC and GA. Strong subsidence across the area is leading to higher temps this afternoon than yesterday, low to mid 90s. The surface ridge will shift east tonight and the low-level moisture will increase, especially in the SC Piedmont where south/south-westerly flow will be a little stronger around ridge. Expect precipitable water to rise above 1.6-1.7 inches overnight. Skies mainly clear overnight although some patchy stratus may develop toward daybreak due to increase in low-level moisture. Guidance temps consistent with lows in the low to mid 70s. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Key Message(s): - Heat Index values up to 110 possible Friday. A Heat Advisory may be needed. Upper level ridging will build over the Forecast Area (FA) during the short term as low level moisture increases through southerly flow. The main concern for the period will be Friday afternoon where Heat Index values should reach the 105 to 110 range. With PWAT values increasing to near 2 inches on Friday and upper ridging over the FA there should be sufficient heat and moisture to raise heat-related illness concerns and may prompt a Heat Advisory. Thursday afternoon appears too dry to meet criteria with afternoon dewpoints mixing into the 60s. Showers are unlikely Thursday due to a drier airmass and warm temps aloft. However we can`t rule out an isolated shower or weak storm in the afternoon. A low number of HREF and SREF members have convective precipitation on Thursday afternoon. On Friday, with temperatures reaching near 100 degrees, closer to the convective temperature, and PWAT values from 1.75 to 2 inches, we are more likely to see isolated or widely scattered storms. Forecast soundings show a tall, skinny CAPE profile indicating limited potential for severe weather. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Key Message(s): - Increased risk of heat-related illnesses this weekend - A Heat Advisory may be needed Saturday and Sunday Moisture continues to increase through the weekend with hot and humid conditions expected through early next week. Heat Index values on Saturday and Sunday of around 110 degrees are possible. Considering non-environmental factors of being a holiday weekend and increased exposure, the risk of heat-related illnesses could be higher than normal. A Heat Advisory may be needed for Saturday and Sunday. However the possibility for decent convective coverage does limit confidence in reaching criteria. Ridging should remain over the Southeast despite an upper trough expected to move through the Great Lakes region Friday and into northern New England on Saturday. A frontal boundary, associated with the trough, will approach the Southeast with significant moisture pooling over our FA. This pattern supports increasing rain chances in the long term with PWAT values slightly above normal. The upper ridge may limit widespread convection, but we should see a chance of rain each day through the extended. The highest rain chances may be Sat and Sun with the weak frontal boundary in the vicinity before it becomes diffuse early next week. Isolated strong or severe storms are possible as afternoon CAPE values increase due to the higher moisture. Near or above normal PWAT values continue through the end of the forecast period supporting climatological rain chances through the long term. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... VFR expected through 06z. The region is under high pressure. Satellite is showing scattered to broken cumulus clouds extending from the coastal area of SC southwest to the Savannah River. Fewer clouds in central SC where the air mass is a little drier. This should continue through the afternoon, then cumulus will dissipate after sunset. Winds variable but favoring east-southeast through the afternoon. Low-level moisture is expected to increase late tonight which may lead to areas of stratus with MVFR/IFR conditions near 12z Thursday. The higher probability of stratus appears to be near the AGS/DNL and OGB terminals. Will add tempo MVFR at those terminals 09z-13z. Lower clouds mixing out by 15z with scattered cumulus developing into the afternoon and south-southwest winds around 5 knots. EXTENDED AVIATION OUTLOOK...Moisture and potential for afternoon showers and thunderstorms and associated restrictions returns through Monday. && .FIRE WEATHER... Key messages(s): -Increased Fire Danger. -Rainfall probabilities increasing over the weekend. Increased fire danger during the Independence Day Holiday week, with temperatures well above normal values. Scattered afternoon and evening thunderstorms, especially by the weekend may aid current dry conditions. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$