####018007655#### FXUS62 KCHS 042236 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 536 PM EST Thu Dec 4 2025 .SYNOPSIS... High pressure will prevail across the region before a frontal system impacts the area Friday into the weekend. High pressure will then return next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Under a broad trough aloft, an inverted surface trough will be building into the region throughout the rest of the afternoon and into the evening hours. Moisture transport in combination with isentropic lift will saturate the atmospheric column from top-down, resulting in increasing coverage of rain showers building in from the west. High temperatures remain seasonably cooler as a result, with highs ranging from the lower 50s to lower 60s, warmest along the coast. Will likely see two rounds of more focused rainfall this afternoon into tonight, each associated with a period of increased frontogenesis at varying levels. The first is building in this afternoon at around the 700mb level, as evident by the band of rain showers on radar, and will be focused further south near/along the I- 16 corridor. However, given the dry air near the surface layer, not expecting more than a tenth of an inch before this band dissipates. As a weak surface low begins to form and move up the inverted trough into southern Georgia overnight, a second band of frontogenesis is expected to form near the 850mb layer. This band is expected to pivot more from the southwest to northeast, and remain across interior southeast Georgia into the midlands of South Carolina. As the surface low continues to approach the region, the 850mb band will be sagging southwards increasing rainfall chances to include coastal southeast South Carolina and coastal southeast Georgia. Overall, the various ensembles would suggest probabilities for a quarter of an inch are highest (40-60%) across interior southeast Georgia and into interior southeast South Carolina, dropping to 10% for those along the coast. Overnight lows are a touch warmer than previous, in the lower to upper 40s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... Multiple rounds of rain are expected Friday through the weekend. Synoptically, the forecast area will remain ahead of mid level trough axis, with a series of shortwaves expected to pass overhead. At the surface, Friday will begin with a ridge of high pressure extending into the Carolinas and an area of low pressure over the northern Gulf. A front will extend from the low across southeast Georgia, and then off the Southeast coast. Through the day, the low will lift northeast along the front. An axis of deeper moisture will become oriented across the region, with PWats expected to surge to over 1.5 inches at times, which is well above normal for this time of year per SPC sounding climatology. Increasing isentropic ascent and larger scale forcing will lead to rain spreading across the area. The highest coverage is expected to be in the daylight hours. Friday rainfall totals are largely 0.75-1.25", except lesser south of I-16, in the 0.25-0.75" range. Additional waves of rainfall are expected Saturday and Sunday. Saturday rainfall totals are forecast to fall in the 0.75-1.25" inch range. Sunday rainfall coverage is a bit more uncertain with larger model spread. Regardless, southeast Georgia should see the higher rainfall totals on that day. NBM indicates the probability for seeing greater than an inch in 24 hours ending Monday morning is only around 10-20%. All in all, the current forecast indicates a widespread 2-3 inches of rain through the event (tonight/Thursday night through Sunday night). No thunder is expected at this time. Luckily, rain rates will not be particularly high and given almost half of the area is classified in severe drought, flooding is not anticipated at this time. && .LONG TERM /MONDAY THROUGH THURSDAY/... The storm system that impacted the area over the weekend will exit, allowing high pressure and drier weather to return. The main weather concern during this time period is the chance for freezing temperatures both Tuesday and Wednesday mornings. The probability for reaching 32F or colder is highest over inland counties, with only a 20-50% chance closer to the coast, roughly along and east of Highway 17 (away from the beaches). && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... 05/00z TAF Discussion: KCHS/KJZI/KSAV: Dry air has kept rain generally confined to sprinkles so far this afternoon/evening. The atmosphere will slowly saturate through the night with cigs expected to slowly lower. As daybreak approaches, things should change quickly as the column becomes nearly saturday in tandem with impulses passing through aloft. This will support an extended period of very low cigs across the region with rounds of light to locally moderate rain falling at all terminals. VFR cigs will give way to LIFR cigs by 13-14z Thursday as vsbys begin to lower with the onset of more significant rainfall. Low cigs, likely below alternate minimums, but above airfield minimums, will persist through the remainder of the 00z TAF period. Rain may begin to pull out after 21z, especailly at KCHS and KJZI, but stratus build-down will likely keep some reductions in vsbys in place with fog. Extended Aviation Outlook: Flight restrictions, likely to IFR or lower, are expected in low clouds and rain Friday into the weekend. && .MARINE... Tonight: No concerns. The pressure pattern will support wind speeds between 10 to 15 kts. Seas will remain between 2 to 3 ft. Friday through Tuesday: Low pressure is expected to pass across the region Friday, with another wave passing through later in the weekend. Rounds of rainfall are expected, but otherwise no marine concerns with winds averaging 15 knots or less and seas 2-4 feet. The storm system should finally pull away on Monday with increasing winds and seas in its wake. Wind gusts and seas could approach Small Craft Advisory criteria Monday into Monday night. No additional concerns anticipated for Tuesday. && .TIDES/COASTAL FLOODING... Astronomical tides will continue to rise with the morning high tide cycles through Friday and remain elevated through the weekend. Coastal Flood Advisories will likely be needed for morning high tide cycles, primarily at Charleston Harbor (Charleston and Coastal Colleton counties) through Sunday morning. Friday, astronomical high tides peak (6.8 ft MLLW at Charleston Harbor and 8.86 ft MLLW at Fort Pulaski) and this is when winds are forecast to turn from the northeast. Overall, this type of setup can over-perform given the building anomalies from the northeast winds. There is potential for tides to reach moderate flooding criteria (7.5 ft MLLW), but current forecast keeps levels just shy. Further south, from Beaufort County through the southeast Georgia coast, the main tide of concern is Friday morning. There is potential for tides to reach minor flooding criteria (9.5 ft MLLW), but current forecast keeps levels just shy. && .CLIMATE... Record Precipitation: December 7: KCHS: 1.14/1976 KCXM: 0.82/1976 KSAV: 0.79/2017 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ ####018005047#### FXUS65 KBOU 042237 AFDBOU Area Forecast Discussion National Weather Service Denver/Boulder CO 337 PM MST Thu Dec 4 2025 .KEY MESSAGES... - Heavy, wind driven snow event likely (>80% chance) for the mountains Friday night through Saturday night, with difficult travel conditions. - Stronger winds at times into early next week. - Milder temperatures ahead, with above normal temperatures by early next week. && .SHORT TERM /Through Friday/... Issued at 216 PM MST Thu Dec 4 2025 Water vapor satellite imagery showing increasing moisture heading towards northern Colorado as a shortwave in the northwest flow aloft nears Colorado. This will bring snow back to the northern mountains for tonight and Friday. Cross sections show the moist layer being somewhat shallow, from the surface to roughly 600mb. This will keep snowfall amounts on the light side across the northern mountains. Just enough snow however for a Winter Weather Advisory for Western Grand and Western Jackson Counties where 4 to 8 inches of snow will be possible tonight and Friday. For the rest of the mountains, up to 5 inches will be possible. For areas east of the Continental Divide, lower surface pressure will bring increasing west to northwest winds to the Front Range mountains and foothills. Some of these gusty winds may spread east of the foothills. Localized blowing snow will be possible, but widespread impacts are not expected. Temperatures are expected to run near to slightly below normal tonight and Friday with highs in the upper 30s to lower 40s across northeast Colorado. Can't rule out a little light rain/snow over the far northeast plains as the shortwave moves across the region. Any precipitation will be very light. && .LONG TERM /Friday night through Thursday/... Issued at 216 PM MST Thu Dec 4 2025 Main story of the long term period is the potentially significant snow/wind event across the mountains this weekend. While snow will be ongoing to start the forecast period, cross- sections are fairly meager with the depth of moisture embedded in the west-northwesterly flow aloft. That will be short lived, as a another shortwave races towards the mountains late Friday night into Saturday. Model cross-sections show well-aligned WNWerly flow with moisture deepening to around 400mb by Saturday morning. As a result, orographic snow should quickly pick up across the mountains, with periods of moderate to heavy snow likely through most of the day Saturday. Considerable blowing snow is also expected, with 30-50kt boundary layer flow likely leading to at least a few gusts of 50-60 mph across favored terrain features. While gusty winds may reduce snow ratios a bit during the period of heavy snow, the combination of snow and wind is expected to lead to widespread travel issues across a majority of our mountain passes. We went with an upgrade to a Winter Storm Warning, and also tweaked the timing a bit to emphasize the period of highest impact across the I-70 corridor. It's possible some impacts extend into Sunday, but a majority of the accumulating snow should fall before midnight Saturday night. Meanwhile, most of the lower elevations should be fairly dry with a modest warming trend over the weekend. There may be a few light rain or snow showers on Saturday as the shortwave passes, but guidance is far from enthusiastic about precipitation chances for most of the I-25 corridor. Highs on Saturday should reach the mid to upper 40s, with low to mid 40s on Sunday. As we enter next week, guidance is in reasonably good agreement with the upper level pattern, as northwest flow continues to prevail across the western CONUS. There will likely be a few periods of snow across the mountains during the week as a few shortwaves pass near the region. There may also be a period of stronger wind gusts on Tuesday or Tuesday night following the passage of a stronger shortwave to the north. Forecast confidence decreases quite a bit by the latter half of next week, though some deterministic guidance tries to bring much warmer weather to the Denver metro and plains closer to next weekend. && .AVIATION /18Z TAFS through 18Z Friday/... Issued at 1036 AM MST Thu Dec 4 2025 VFR to prevail through tonight and Friday. Southerly winds at DEN and APA will weaken and become light and variable 19-21Z. Winds then return to a southerly drainage direction after 00Z Friday. At BJC and areas along the foothills, gusty west winds to 30 knots are expected to develop around 00Z and continue through the night. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to 11 PM MST Friday for COZ031. Winter Storm Warning from 11 PM Friday to 11 PM MST Saturday for COZ031-033-034. && $$ SHORT TERM...12 LONG TERM...Hiris AVIATION...12 ####018007059#### FXUS63 KIND 042237 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 537 PM EST Thu Dec 4 2025 .KEY MESSAGES... - Patchy freezing fog overnight, especially northwestern portions of central Indiana. - Wind chills of few degrees either side of zero will be possible across northern areas early tonight into Friday morning. - Low chances for snow will be around Sunday and again Tuesday. && .SHORT TERM (This evening through Friday)... Issued at 258 PM EST Thu Dec 4 2025 A cold front has passed through Indiana this morning, but is most noticeable across our northwest where temperatures dropped into the low teens. Further south, the advancing cold air mass has slowed and made little progress. In fact, surface winds are now veering as surface high pressure skirts eastward across northern Indiana. This will allow winds to go light and variable overnight before switching to southwesterly tomorrow. As mentioned above, winds become light and variable under the high along with clearing skies. This should promote ideal radiative cooling potential especially where a deeper snowpack exists. The deeper snowpack is generally across our northwest, which is coincidentally also deeper into the colder air mass which dropped south last night. As such, we're expecting our coldest reading overnight to be over our northwestern counties. Lows in the single digits will be common, along with the potential for some negative temperatures here and there. Further south, lows in the single digits are possible but teens should be more common. High resolution guidance is hinting at patchy fog potential overnight, especially further north and west where the best cooling potential exists. The air mass that moved south was dry, not overly so, but dry enough to make the idea of widespread fog seem unlikely. We'll introduce the mention of patchy fog for western and northern portions of our CWA. Should fog occur, it will coincide with the very cold temperatures expected overnight. Therefore, we'll mention it as freezing fog which carries the potential for light icing on cold surfaces. As high pressure lift northeastward on Friday, winds will turn southwesterly and increase ahead of a trough approaching from the northwest. Low stratus is possible Friday morning into the afternoon but is conditional on fog development. Regardless, enough sunshine looks to be present, along with warm air advection from the southwest, to allow temps to rebound into the upper 20s / low 30s. && .LONG TERM (Friday night through Thursday)... Issued at 258 PM EST Thu Dec 4 2025 Ridging aloft will remain confined to the Pacific coast through much of the extended before gradually shifting east into the Plains by late next week. This will maintain an eastern upper level trough and broad northwest flow across the region keeping temperatures largely colder than normal with a few clipper like systems offering the opportunity for light snow as well. Friday Night through Sunday Clouds will thicken Friday night into Saturday as a weak frontal boundary drifts into the Ohio Valley before washing out. Moisture will be lacking with the front and expect dry conditions for central Indiana through Saturday night with seasonably cool temperatures. Highs will rise above freezing into the mid and upper 30s over most of the forecast area Saturday afternoon as light southerly flow develops. Extended model guidance over the last few runs has trended back in the direction of the potential for a period with more widespread light precipitation associated with a clipper system set to track from the northern Rockies on Saturday into the region by Sunday afternoon. Moisture will be more plentiful along and ahead of this feature with growing confidence of a 6 to 8 hour period on Sunday with precipitation impacting the region. Low level thermals will be critical with a potential for rain to mix with snow across southern portions of central Indiana while the airmass remains cold enough for just snow further north. The track of the system will be the determining factor on precip type as a further shift south would support more snow over the area while a northerly track would favor an increased risk for mixed precipitation or even a period with primarily light rain. Ensembles continue to align but there is potential for a light snow accumulation focused especially across the northern half of the forecast area on Sunday. At this point...impacts would likely be minor and certainly lower than both of the recent storms last weekend and on Monday afternoon and night. Sunday Night through Thursday In the wake of the clipper on Sunday...a reinforcing shot of Arctic air will follow in tandem with strong high pressure to begin next week with highs reverting back into the 20s over a large portion of the forecast area on Monday. The high will be east of the region by Tuesday with return flow enabling temperatures to rise into the 30s on Tuesday with mid 30s to mid 40s Wednesday. Uncertainty increases in regards to precip chances but the overall pattern aloft supports one or two systems dropping southeast through the Great Lakes and bringing at least the potential for light precipitation including snow for the middle and latter part of next week. An amplification of the upper trough will bring another surge of colder Arctic air by next Thursday and Friday but that will be temporary as the aforementioned western ridge is expected to move into the eastern half of the country by next weekend with warmer temperatures and a brief break from the early winter conditions. Long range trends do support a return to colder and more unsettled conditions as we approach the weekend prior to Christmas. && .AVIATION (00Z TAF Issuance)... Issued at 537 PM EST Thu Dec 4 2025 Impacts: - Patchy fog possible overnight, mainly HUF and LAF - MVFR stratus possible Friday morning/afternoon, mainly at BMG Discussion: VFR conditions expected through much of the TAF period outside of patchy fog towards LAF and HUF and MVFR cigs towards BMG. Confidence is increasing in at least a period of IFR if not LIFR vsbys towards LAF with lower chances at HUF due to patchy freezing fog. This fog may settle is as early as 06Z but becomes more likely in the 10z to 14Z timeframe. Cigs should remain VFr outside of a low chance at BMG towards daybreak as low stratus builds across southern Indiana. Winds will be variable through the period at 0-6kts with a predominately northeasterly direction tonight and southerly direction tomorrow. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Eckhoff LONG TERM...Ryan AVIATION...White ####018006458#### FXUS66 KMFR 042238 AFDMFR Area Forecast Discussion National Weather Service Medford OR 238 PM PST Thu Dec 4 2025 .DISCUSSION...The battle zone between dry and wet will be SW Oregon and northern California for at least the next week. Model guidance is near unanimous in showing a strong, moist upper level jet and ARs directed into British Columbia and portions of the PacNW (especially northern Oregon and Washington) through next Thursday. But, strong high pressure aloft currently situated between 30 and 40N and around 140W will gradually drift ESE during this time period and will serve to deflect most of the heaviest precipitation associated with the jet to our north. At times, however, shortwave disturbances will allow for frontal systems to wag to the south and bring some rain to our area. With the main activity/fronts remaining to the north, this should also keep temperatures above normal for early December and snowfall will be limited in the mountains. One such system is expected to come over the top the offshore ridge on Friday, with a slug of moderate to perhaps briefly heavy precipitation focused in Coos and Douglas counties, especially the coast and coast ranges, but also the Cascades and adjacent west side foothills. Snow levels are up around 9000 feet Friday, so precipitation will be rain, even at the higher mountains. Most likely rain amounts in those areas will be 0.50-1.50 inches, perhaps slightly higher in areas of higher orographic enhancement (NNW-facing slopes of Cascades). But, this isn't the type of flow that brings a lot of rain to the Rogue/Illinois valleys, so amounts drop off significantly, to around 0.10-0.25 of an inch. South and east of the Cascades, some places won't measure any rainfall, but a few hundredths here and there will be the general rule, again aside from any NNW-facing terrain enhancement. Models are showing a mid-level jet of 45-50 kt around 700 mb late Friday afternoon/night and this could bring gusts up to 45 mph over the higher terrain and the East Side (Summer Lake region) then. We don't think this will affect a large area, so we aren't putting up a wind advisory, but hunters or others venturing into the mountains should be aware of potentially gusty winds. Gradually, snow levels fall to 5500-6000 feet by Saturday morning, but precipitation should be tapering off or ending by then. Some light rain/drizzle has the highest probability of persisting along the coast and into the Umpqua Basin during Saturday. After a break Saturday/Saturday night, the next disturbance will move over the top and into WA/OR Sunday. This will bring a renewed risk of moderate precipitation across N&W sections of the CWA, once again with most, if not all, precipitation staying to the north of the OR/CA border. We don't currently predict any measurable rainfall here in Medford, but there could be a 0.10-0.30 of an inch from the coast to the Umpqua Divide/Cascades. The Pacific fire hose will continue to wag back and forth Tuesday through Thursday with models showing a warm front shifting north of the area and snow levels once again rising above 8000 feet. The force field still appears to be the OR/CA border, with precipitation really struggling to reach into NorCal during the stretch. Right now, we can expect some minor rises on area creeks, streams and rivers across N&W sections of the CWA (up around Roseburg and north/west), but since they're running low for this time of year, we don't expect flooding. Most significant impacts from the rain will be to our north. Beyond that, model clusters/ensembles are generally split between the upper ridge moving onshore into the SW late next week and then into the nation's midsection over the weekend or upper ridging holding in the SW longer. If the pattern is more progressive, upper troughing over the north Pacific/Gulf of Alaska could head in our direction Fri/Sat. Right now, about 20-40% of the membership show a colder solution with the potential for lower snow levels. However, more likely, some semblance of the upper ridge remains over the SW with a shift in the storm track slightly southward with time. This is likely due to some blocking expected downstream. This brings better odds for precip here, but with temps remaining near to above normal. CPC 8-14 day forecast is showing this scenario with better odds for above normal temps continuing through Week 2, but also a higher probability of above normal precip. Since there are many scenarios and plenty can change between now and then, we'd recommend checking back for updates! -Spilde && 04/18z TAFs...VFR will prevail for most areas this afternoon. A weak front is crossing through the area today, with periods of light rain expected along the coast and into the Umpqua and southern Oregon Cascades this afternoon and tonight. Low clouds will spread inland late this afternoon and this evening, with MVFR and IFR developing along the coast inland to the Cascades. From the southern Oregon Cascades west, ceilings are expected to lower overnight to IFR/LIFR with IFR visibilities. Mountain obscurations are likely. Areas of MVFR ceilings may spread east of the Cascades and into portions of northern California late Thursday night. Lower flight conditions will continue through at least Friday morning. -BPN && .MARINE...Updated 200 PM PST Thursday, December 4, 2025...North winds will transition towards the south and west today and tonight as a front passes through the area. The combination of residual north wind seas and new south/west wind seas will result in somewhat chaotic seas today into Friday. Then, gusty south winds and west swell will produce continued steep seas Saturday night into Sunday. Conditions remain unsettled through the first part of next week, with several passing fronts bringing periods of gusty south winds and continued steep combined seas. -BPN && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory from 4 PM this afternoon to 4 PM PST Saturday for PZZ350-370. Small Craft Advisory until 4 PM PST Saturday for PZZ356-376. && $$ MAS/BPN