Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/05/18

Area Forecast Discussion...UPDATED
National Weather Service Charleston SC
947 PM EST Sun Nov 4 2018 .SYNOPSIS... A coastal trough will affect the area tonight and Monday before a cold front sweeps through Tuesday night. A warm front will lift north Thursday then a cold front will move through Friday night. High pressure will then build in next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The coastal front is showing signs of moving closer to the coast as weak low pressure develops along it. Temperatures along portions of the Georgia and lower South Carolina coast have risen 1-2 degrees within the last hour, even as rain falls. Low-level convergence is steadily building along the coast as the surface waves becomes better defined. This increased convergence coupled with strong isentropic assent atop the inland wedge and coastal trough will support widespread shower activity across the coastal counties for the next few hours until the surface waves passes off to the northeast. Pops will range from 100% at the coast to 30-50% in the Millen- Allendale-Cat Hole corridor. The rain could be moderate to locally heavy at times, but no major flooding problems are expected. Have seen A few lightning detections on both GOES-E GLM and the LDN across parts of Southeast Georgia. Still think the best instability will remain over the coastal waters, but there looks to be enough elevated instability along the cool side of the coastal trough to support a few tstms. Expanded a slight chance of tstms to include all coastal counties. Still think there is a non-zero risk for an isolated tornado along parts of the Charleston Tri-County area, mainly along the Charleston County coast, where the latest RAP still shows the EHI peaking around 1 unit and SigTor reaching near 2 unites ahead of the surface wave. Pinning down lows is proving very tricky as hourly temperatures will be driven by the ultimate position of the coastal trough and frontal wave. Latest high resolution guidance supports a slightly larger and warmer warm sector ahead of the wave. This will result in temperatures slowly rising in a few areas, especially along parts of southern South Carolina. Lows will range from the lower 60s well inland to the mid-upper 60s at the coast. Conditions appear favorable for areas of fog to develop across interior Southeast Georgia early Monday in the wake of the surface wave. The fog will be the result of stratus build-down and there are a number of guidance packages supporting dense fog with vsbys 1/4 mile less. Latest NARRE-TL shows probabilities of 60-70% for vsbys <1/4 mile roughly along/west of an Allendale-Glennville line. Maintained "areas of fog" in this region and will update the HWO include a mention for possible dense fog development. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Shortwave troughing aloft will continue to dampen as it rides northeast along the longwave trough as a trailing shortwave begins to deepen while sliding east. By late in the day, this trough develops more of a positive tilt while over the central U.S. Locally, the forecast area remains near the broader mid-upper longwave trough while better model agreement suggests the coastal trough slides inland and weakens through the day, bringing precipitation potential for much of the day, declining later in the evening. Mostly dry conditions over land zones are expected overnight into early Tuesday. A surface cold front trailing a strengthening low pressure system moving northeast across the Great Lakes region will cross the forecast area late Tuesday night into early Wednesday morning. The best forcing and associated risk of severe weather is expected to remain farther inland and north of the forecast area. At least a period of drying is anticipated behind frontal passage, but synoptic models show the front stalling just south of the area, with moist southerly flow likely leading to some degree of overrunning precipitation which could spread over the forecast area Wednesday, mainly during the afternoon and evening. Because of this, slight chance to chance POPs will be maintained. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A broad upper trough remaining over the central United States results in lower than normal forecast confidence in the long term. Models have shown poor run-to-run consistency beyond Thursday as there will be the potential for a series of fronts to develop and affect the Southeast during the period. The one feature that continues to appear is a cold frontal passage Friday or Friday night. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... KCHS: Showers will impact the terminal in some form through about 05z with the bulk of the activity pushing east/northeast as a wave of low pressure develops along the coastal trough. Risk for tstms is low. MVFR vsbys/cigs will be possible during this time with MVFR cigs lingering through mid-morning Monday before lifting. Best chances for IFR look to remain west and southwest of the terminal. KSAV: Rain showers will impact the terminal through about 03z after which the bulk of the activity will push northeast of the terminal as weak low pressure develops along the coastal trough. As the low pulls away, expect low stratus to overspread the terminal from the west as the coastal trough is forest to remain just offshore. The lowest conditions still look to remain west of the terminal, but still expect IFR cigs to move in. Right now, do not anticipate cigs any lower than 700 ft and vsbys in light fog no lower than 4SM. MVFR will return by mid- morning with VFR by noon. Extended Aviation Outlook: Periods of flight restrictions will be possible at both terminals through Tuesday due primarily to low ceilings. Additionally, fog will be possible overnight Monday into Tuesday, and shower and/or thunderstorm activity could briefly reduce surface vsbys. && .MARINE... Tonight: The tightest pressure gradient is working up the coast this evening ahead of a weak surface low developing along the coastal trough. Extended the Small Craft Advisory for the South Carolina waters through 1 AM for gusts to 25 kt. Winds are expected to diminish as the coastal trough works to the coast and low pressure develops along it. Advisory through 10 PM looks fine for now. Monday through Friday: Generally onshore flow 10-15 knots will persist into Tuesday before veering northeast behind a passing cold front late Tuesday into early Wednesday with a coincident uptick in windspeeds which are still expected to remain below Small Craft Advisory levels. Anticipate northeast flow to persist through Thursday. The greatest chance for winds/seas reaching Small Craft Advisory criteria will be Friday night into Saturday behind a stronger cold front. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 1 AM EST Monday for AMZ350-352. && $$
Area Forecast Discussion
National Weather Service Memphis TN
910 PM CST Sun Nov 4 2018 .UPDATE... A few light showers continue to affect portions the Mid-South this evening as an upper trof continues to move through the area. The trof will lift into the Ohio Valley by midnight. This should bring an end to the chances of rain. The HRRR indicates that dense fog may develop during the overnight hours especially across North Mississippi and portions of West Tennessee. The forecast already has mention of patchy fog, but will monitor for a possible Dense Fog Advisory. For now, current forecast looks good. KRM && .DISCUSSION... /issued 322 PM CST Sun Nov 4 2018/ Skies have cleared across much of east Arkansas with cloudy skies over the remainder of the forecast area. Temperatures this afternoon range from the mid 50s to lower 60s. A large area of light rain continues to move across much of north Mississippi and a small portion of west Tennessee with some additional showers about to cross the Mississippi River. All of this activity is ahead of a weak cold front which is just west of the forecast area. As this front moves through the forecast area tonight, rain should move out of the region tonight. Skies should clear some overnight and with light winds and wet grounds, some patchy areas of fog may develop. Temperatures will be on the cool side with lows Monday morning in the mid 40s to around 50 degrees. On Monday morning, the cold front will lift back north through the region as a warm front with some isolated showers possible. Behind the warm front, milder air will move into the region allowing temperatures to warm into the mid 60s to lower 70s. By Monday afternoon, a strong cold front will be moving across the southern plains and into western Arkansas. Numerous thunderstorms are expected to develop ahead of this front and move into the forecast area. As the front moves closer to the Mississippi River, there will be a better chance for some of these thunderstorms to become severe. The main threat with these storms will be damaging winds. Tornadoes, locally heavy rainfall and large hail are also possible. The main time frame for severe weather in our area will start around 2 pm in east Arkansas and end around 2 am in northeast Mississippi. By Tuesday, the cold front will be east of the region so rain will be ending in the morning over far eastern sections of the forecast area. Temperatures will not be that much cooler than Monday with highs in the mid 60s to lower 70s. On Wednesday, another cold front will drop into the region from the north. This front will produce some additional rain showers for both Wednesday and Wednesday night. By Thursday, a storm system will move into west Texas and move rapidly northeast reaching the Ohio Valley by Friday morning. This system will bring another cold front through the forecast area with more rain expected for Thursday, Thursday night and Friday. High pressure will start to build into the region by Friday afternoon bringing dry weather and colder temperatures. The dry and colder weather will continue through much of next weekend. Low temperatures both Saturday morning and Sunday morning will be in the 30s so some frost and even a freeze is possible. ARS && .AVIATION... Band of rain is moving very slowly east as a cold front stalls and weakens. Clouds are breaking up across KJBR and KMEM with VFR conds expected through much of the night. Fog is possible later tonight. KMKL should keep a MVFR cig overnight as clearing line will likely stall to the west. Low cigs will remain at KTUP with dense fog likely late tonight. As the front lifts back north as a warm front some dense fog could lift north into KMEM early Monday morning. Confidence is not high enough to place in the TAF but will be on the lookout. Low clouds will spread across the entire area Sunday morning with south winds around 10 kts. A potent system will push into the region Monday afternoon with numerous SHRAs and TSRAs during the latter parts of the period. SJM && && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Marquette MI
641 PM EST Sun Nov 4 2018 .SHORT TERM...(This evening through Monday) Issued at 317 PM EST SUN NOV 4 2018 WV imagery and RAP analysis indicated a mid/upper trough into the central CONUS with a vigorous shortwave trough lifting northward through central WI which supported a broad area of light to moderate precipitation from ern MN through WI into IL. Colder air north of the low has also resulting in bands of moderate to briefly heavy snow from nw WI into western Upper Michigan snow has accumulated to 1 to 3 inches. However, radar trends and sfc obs showed that the snow was diminishing near KIWD/KLNL/KEGV with a changeover to rain at KPBH/KRHI. Snow as finally increasing over the higher terrain in north central Upper Michigan with minimal accumulations. Tonight, expect the snow to continue to diminish from south to north as the stronger WAA/295k isentropic ascent lifts quickly to the north. As the low moves toward western Lake Superior, warmer air moving in from the south will also change the remaining to snow to rain this evening. Temps should also climb to around 40 west half to the low to mid 40s over the eastern cwa. The more significant pcpn will shift into the east overnight in line with the stronger moisture transport and remaining 700-300 mb qvector conv and isentropic lift. With the dry slot moving into the west, much of the pcpn may be drizzle with little pcpn where downslope sse low level flow prevails. Monday, there may some leftover light rain or drizzle in the morning over mainly the east until the sfc trough axis moves through the area. SW low level flow will bring slightly drier air into the region. However, enough low level moisture will remain to maintain the cloud cover and limit high temps to around 40 west to the mid 40s east. .LONG TERM...(Monday night through Sunday) Issued at 258 PM EST SUN NOV 4 2018 Overall, we`re looking at an active weather week with chances for precipitation almost every day with a couple of systems tracking across the region and the arrival of what looks to be the first real good shot at accumulating lake effect/enhancement snow later this week and weekend. There is still quite a bit of uncertainty in how these systems will evolve as they move across the Great Lakes; however, we certainly will be on a cooling trend through the upcoming weekend. The earlier part in the week expect day time highs in the low to mid 40s and overnight lows in the low to mid 30s. Through the end of the week, temperatures will gradually cool into the teens and upper 20s for overnight lows and low to mid 30s for afternoon highs. Tuesday/Wednesday, the complicating factor with this time period is the multiple waves moving across the Great Lakes Region. The first is the southern stream lifting northeast out of the Plains and up across the eastern Great Lakes, with the deepening area of low pressure tracking further south and east than what model guidance suggested over the last couple of days. Given the further southeast storm track, impacts from this system will be well removed from the Upper Peninsula. We will however see precipitation from the second wave progged to dig across the northern Plains and over across the Western Great Lakes. This wave will result in either the development of a secondary low pressure system, or an extension of troughing off of the main low pressure system well east of the region. With the colder air still behind this secondary wave, it appears that most of the precipitation will remain all rain through much of Tuesday. Tuesday evening into Wednesday as the main 850mb low pivots east across the area, colder air moving in from Canada will support the transition over to snow. Expect lingering lake effect/enhanced snow showers Wednesday across the northwest wind snow belts in western Upper Michigan as cold air advection continues to drop across Lake Superior. Further east, the colder air doesn`t look to arrive until Wednesday night, switching lake effect/enhanced rain showers over to snow. Thursday through this weekend, lingering lake effect snow will become enhanced at times as another wave digs south across the Upper Great Lakes and supplies additional lift/support to deepening ongoing convection. This will mean that at times snow showers will push further inland from the typical lake effect snow bands. With 850mb temperatures progged to drop as low -12 to -15C, certainly not out of the question we could see moderate to heavy lake effect snow showers at times. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 640 PM EST SUN NOV 4 2018 As a weakening low pres system lifts from western WI this evening to northern Ontario on Mon, pcpn will diminish tonight at all terminals. Any snow or snow/rain mix at the beginning of the fcst period will change over to all rain by mid evening. While prevailing IFR conditions are expected at KSAW tonight, KIWD/KCMX will likely fluctuate btwn IFR and low MVFR. Overnight, KSAW will probably slip down to LIFR under an upslope sse wind. Slightly drier air will arrive on Mon, and that will likely lead to prevailing MVFR conditions developing at all terminals. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 258 PM EST SUN NOV 4 2018 East-southeast gales of 35 to 40 knots have begun to overspread Lake Superior as low pressure lifts northeast this afternoon. Expect these winds to continue through the overnight hours, before gradually diminishing to 20 to 30 knots from the southwest Monday morning. Winds look to further diminish to less than 15 knots Tuesday as the pressure gradient relaxes with broad troughing expected to develop over Lake Superior. However, this period with lighter winds will be short-lived as winds become northwesterly 20 to 25 knots Tuesday night through Thursday as colder air works down across the Upper Great Lakes. Towards the end of the week, another low pressure system progged to develop over the Upper Great Lakes will need to be monitored for the potential for gales. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 7 PM EST /6 PM CST/ this evening for MIZ002-004-009-010-084. Lake Superior... Gale Warning until 4 AM EST Monday for LSZ250-251-264-266-267. Gale Warning until 10 PM EST /9 PM CST/ this evening for LSZ162- 246>248. Gale Warning until 1 AM EST Monday for LSZ244-245-263-265. Lake Michigan... Gale Warning until 4 AM EST Monday for LMZ248. Gale Warning until 1 AM EST Monday for LMZ221-250. && $$ SHORT TERM...JLB LONG TERM...Ritzman AVIATION...Rolfson MARINE...Ritzman
Area Forecast Discussion
National Weather Service Blacksburg VA
630 PM EST Sun Nov 4 2018 .SYNOPSIS... Low pressure forms along a coastal front tonight and sends clouds and rain back into the area overnight. Cloudy skies along with intervals of light rain and fog for Monday as a shallow wedge of high pressure builds back southward. A stronger storm system affects the region on Tuesday bringing a threat of showers and thunderstorms, followed by drier weather under high pressure on Wednesday. && .NEAR TERM /THROUGH MONDAY/... Update as of 630 PM EST Sunday... Previous forecast looks fairly on track. Did adjust PoPs up slightly along the Blue Ridge at the onset of precipitation based on latest ConShort and HRRR. Increased moisture from the south as mentioned in the previous discussion is beginning to show itself in observations as cloud heights are noticeably lowering across the forecast area. As this moisture continues to increase ahead of the approaching frontal system, still can reasonably continue to forecast precipitation becoming more widespread across the forecast area around midnight. As of 335 PM EST Sunday... Established wedge in place across the mid-Atlantic, Appalachians and Carolinas remains in place this afternoon with a continued dry forecast through the late afternoon hours. Will start to see an increase in clouds early this evening across our NC counties and advancing northward across VA/WV into the mid-evening, as Atlantic moisture associated with the southern end of a frontal boundary which moved off the Atlantic seaboard late last week returns northward atop the wedge. This shield of steady rains should be infused by a southerly low-level jet progged to increase to 40-45 kts, eventually linking up with an occluding frontal system moving into the eastern Ohio Valley and western Appalachians. Think the NMM- WRF and the 3-km NAM showing steady rain in the Piedmont starting early this evening is overdone. Have followed the later HRRR and the GFS which supports rain beginning closer to midnight near and east of the Blue Ridge. Areas including far southwest VA and into southeastern WV likely will see steady rain beginning in the wee hrs of Monday morning tied to the frontal occlusion. Overall expect rain to be at least steady light to moderate-intensity. Rain should be moving along to the northeast at a good clip given the strong winds aloft, with rain moving into the Shenandoah Valley and north-central VA toward the Monday morning commute. In terms of rain amounts, stayed largely with a blend of WPC and the NAM, with rain totals around a third to half-inch across the Southside and Piedmont, quarter to a third of an inch across the Mountain Empire into southeast WV, with higher amounts of half to three quarters an inch along either side of the Blue Ridge. Opted for a non-diurnal temperature trend with most areas seeing temperatures tending to hover or slowly rise overnight with best warm advection. Lows mainly in the 40s except low/mid 50s in the NC Piedmont and Southside. Majority of model guidance shows the wedge, which had briefly weakened/retreated north with the rain from overnight, eventually re- settling back southward across the area on Monday. Other than in our far southwestern counties, expect a cloudy, gray Monday across the forecast area as moisture remains trapped under a stout temperature inversion. Though the bulk of the steadier rains will have ended early Monday, have shown limited chances for very light rain or drizzle, and with light north winds did include patchy mist or fog. Temperatures likely to rise only very slowly on Monday mainly in the 50s given overcast, though a few lower 60s possible towards the Mountain Empire into Mercer County where some breaks in overcast look likely. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 230 PM EST Sunday... Dynamic upper trough to the northwest Monday night will push its associated cold front to just west of the Appalachians by daybreak Tuesday. This should also aid deepening warm advection allowing the low level wedge to break down from southwest to northeast overnight as a warm front lifts north across much of the region by Tuesday morning. Some degree of warm advection showers likely with the passage of this boundary and also within the increasing warm sector through midday Tuesday. However coverage remains uncertain espcly given much stronger lift/convergence with the cold front to the west, but appears still enough for increasing pops to likelys west Monday night at this point. Other concern with winds mainly along the western ridges as the 85h jet ramps up to around 50 kts later Monday night. This may produce gusts to around advisory levels BLF vicinity late Monday night into early Tuesday. However these potential higher speeds may be more associated with showers given more of a southwest trajectory, and model soundings showing the stronger winds above the near surface stable layer. Lows overall in the 50s espcly early before likely rising with the exodus of the wedge late. Cold front crosses the region from the west on Tuesday with guidance perhaps a bit slower than previous given best support lifting by well to the northwest. Scenario still appears to suggest residual showers over the mountains Tuesday morning with either these fading or some redevelopment of narrow bands just east of the Blue Ridge Tuesday afternoon. These bands again low topped with perhaps little thunder and possibly embedded within the very strong unidirectional wind field aloft. Latest models suggest best shot at organization and wind producing severe storms across the southeast counties around mid afternoon before quickly exiting to the southeast per consensus. More expansive shower/cloud coverage early on could also play into limiting already weak instability, but likely overcome by shear espcly given helicity off latest progged soundings. Thus will beef up pops some for more linear aspects to shower/storms and keep severe mention in the HWO per the going DAY3 outlook. Otherwise breezy and mild with highs 60s mountains to low/mid 70s east. Front exits the region Tuesday evening allowing a very fast zonal flow aloft to take shape with high pressure bridging in from the northwest into Wednesday night. This looks to bring in much drier air espcly aloft by Wednesday under west/northwest flow. Brief punch of stronger winds will be possible Tuesday night behind the front but given only a 25-30 kt 850 mb jet and weak cool advection, appears will stay below advisory levels, with less wind Wednesday into the overnight under the ridge axis. Also post frontal upslope moisture quite shallow so expect only some spotty showers at most far northwest Tuesday night before things clear out Wednesday despite lingering high clouds. Will see temps lower about a category or two behind the front but overall still above normal with mostly 60s Wednesday, except around 70 east given downsloping. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 215 PM EST Sunday... Flat 500 mb flow will again sharpen up from the southwest heading into the end of the week in response to the next strong upper low pivoting east toward the Great Lakes by Saturday. This backing flow should again start to bring overrunning moisture back northeast toward the area during Thursday with possible deeper moisture over the region Thursday night into Friday evening. However model spread has become even larger today with quite a difference in some phasing northern/southern energy and others much flatter under more sheared upper support. This would include the wetter operational GFS/CMC solutions from yesterday, that have switched to a much more shunted scenario per weak low pressure either offshore or to the south. This in contrast to the stronger 12z ECWMF and FV3-GFS which support a more pronounced swath of deeper moisture heading up across the region later Thursday night into Friday with a subsequent frontal passage Friday night. Since this remains more consistent with trends from yesterday and still supported by a few GFS ensembles members will keep higher pops during this period before tapering off Friday night when a few snow showers could still occur over the west. Otherwise highs mostly in the 50s to lower 60s Thursday/Friday pending clouds and eventual rainfall to end the week. Secondary shortwave swings by to the north over the weekend allowing better cold advection to get a southeast push resulting in drier and colder weather for the weekend. Latest progs suggest that the coldest air will remain north but enough cold advection Saturday to keep highs 40s west to low 50s east and similar Sunday but under less wind. Coldest night also likely Saturday night as the surface high settles overhead allowing for lows mostly in the 20s to around 30 east. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 630 PM EST Sunday... Poor flying conditions are expected through the TAF period as increasing moisture riding into the region on a low level jet will combine with an approaching frontal system to drop ceilings and visibility to sub-VFR in low clouds, rain, and fog. Any location that will begin in VFR will see those conditions deteriorate within the next couple of hours. Rain could be heavy at times overnight, particularly out east. By the morning, heaviest rains should be finished however the wedge that will weaken slightly with passage of the front will re-establish itself creating gloomy conditions for Monday with continued low ceilings and lingering drizzle and fog at many locations throughout the day. Winds will be from the east/southeast and light, but a bit more pronounced, going into the forecast period than it will become tonight, changing to very light and variable tonight through the end of the forecast. Forecast confidence is high on conditions being sub-VFR through this TAF period, but does wane as far as timing out and severity of MVFR and IFR conditions. Further, latest LAMP guidance does suggest that LIFR conditions could be possible for short periods of time at some locations, however have opted not to advertise it in the TAFs themselves as enough uncertainty is already in play regarding changes to the conditions. Extended Discussion... Sub-VFR to continue into Monday night with trapped moisture under wedge, periods of low clouds and intervals of mist likely. The first of a couple of major weather systems digs into the southeast U.S. on Tuesday. Winds, low ceilings, and low visibilities in showers and thunderstorms can be expected, with a period of high winds possible. Improvement in ceilings/visbys likely Wednesday though still breezy until Wednesday evening. Second major weather system affects the region on Thursday with good potential for sub-VFR. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AL NEAR TERM...AL/JR SHORT TERM...JH LONG TERM...JH AVIATION...AL/JR/WP