Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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426 FXUS62 KCAE 031029 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 629 AM EDT Wed Jul 3 2024 .SYNOPSIS... Moisture increases through the week and into the weekend with isolated to widely scattered convection possible each afternoon. Ridging builds into the area late this week and into the weekend resulting in above normal temperatures and Heat Index values near 110 possible. && .NEAR TERM /THROUGH TONIGHT/... Key Message(s): - Increasing temperatures today Ridging continues to set over top of the region this morning and is helping to keep things quiet across the region today. Surface high pressure has shifted eastward, allowing the surface ridge axis to shift a bit. Southeasterly flow has commenced as a result, which has slowly allowed dewpoints to creep back up into the upper 60s and lower 70s most places. Despite this, PWs remain seasonally low across the region which should allow for at least once more day of bearable afternoon humidity. However, temps should warm quite a bit. Not expecting upper 90s quite yet today as HREF mean 850 hPa temps are ~16-18C, which would yield low to mid 90s for most this afternoon. Given subsidence aloft with the ridge overhead, not expecting any precip this afternoon. Given rise in dewpoints, overnight lows tonight should only fall into the low 70s across the FA. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... Key Message(s): - Temperatures pushing 100 degrees by Friday - Low level moisture increasing through Friday - Heat Index values up to 105-100 possible Thu/Fri afternoon Thursday and Thursday night: Upper ridge remains positioned over the deep south and southeastern states on Thursday while surface high pressure will be off the coast allowing for a warm southerly flow to return. This will support higher dewpoints and therefore higher heat index values with values as high as 105 degrees possible. Forecast soundings show a capping inversion around 700mb which will limit convection along with no real upper forcing mechanisms but temperatures under the upper ridge will be pushing back into the mid and upper 90s. PWAT values will begin rising again to around normal with ensemble mean forecast values around 1.8 inches. Cannot rule out isolated convection but severe storm threat seems low given generally weak instability and plenty of mid level dry air that could entrain into any storms that develop. Friday and Friday night: Upper ridge holds strong on Friday despite a deepening upper low moving into the Great Lakes region. Continued low level southerly flow should support increasing low level moisture advection as ensemble mean PWATs are forecast to rise to around 1.9-2.0 inches. Temperatures should warm further with highs in the upper 90s to around 100 degrees. Dewpoints in the 70s should support heat index values approaching or exceeding heat advisory criteria (108 degrees). The capping inversion around 700mb is still present on forecast soundings but a bit weaker and with temperatures pushing 100 degrees think isolated to scattered convection will be possible. Again, instability is not forecast to be very strong but if moisture is a bit higher than forecast that could result in higher instability and a possible low pulse severe threat. Not much relief at night expected with warm overnight lows in the 70s. && .LONG TERM /SATURDAY THROUGH TUESDAY/... Key Message(s): - Heat Advisory Criteria possible this weekend - Thunderstorm chances increase this weekend into next week An upper trough is expected to move through the Great Lakes region Friday and into northern New England on Saturday but does not appear strong enough to break the upper ridge over the southeast states. However, the trough should push a frontal boundary near the area with significant moisture pooling just ahead of it over our forecast area with LREF ensemble showing probabilities of PWATs greater than 2 inches at 60-80%. Despite the increasing moisture the presence of the upper ridge may limit widespread convection, but we should see some chances of rain each day through the extended with the highest pops Sat/Sun with the weak frontal boundary in the vicinity before it becomes diffuse early next week. Widespread severe weather is not expected but cannot rule out isolated pulse severe storms and the above normal moisture should provide an increased local heavy rain threat as well. Hot and humid conditions expected Saturday with highs around 100 degrees and heat indices approaching 110 degrees. Increased cloud cover and convection should help limit high temperatures Sunday into early next week. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... VFR conditions expected to dominate the period. Quiet TAF period is expected overall today as high pressure dominates the region. Stratus did not form near the Augusta sites last night, so nothing of note to mention in the immediate term with respect to restrictions. Mostly clear skies will take us through most of the day with generally easterly winds between 5 and 10 knots expected. Some stratus is being shown by guidance towards the end of the period tonight, so hedged in that direction without explicitly forecasting restrictions in the TAF at this time. EXTENDED AVIATION OUTLOOK...Moisture and potential for afternoon showers and thunderstorms and associated restrictions returns Thursday through Sunday. && .FIRE WEATHER... Key messages(s): -Increased Fire Danger mid to late week. -Rainfall probabilities remain relatively low mid week. Increased fire danger during the Independence Day Holiday week, especially late week as temperatures rise again to well above normal values. Scattered afternoon and evening thunderstorms possibly may aid current dry conditions. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$