Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/26/17

Area Forecast Discussion
National Weather Service Bismarck ND
934 PM CDT Sat Mar 25 2017 .UPDATE... Issued at 926 PM CDT Sat Mar 25 2017 Have backed off a bit more on the timing of potential rain over the southwest/south central in line with latest guidance. Have also trimmed down precipitation chances over northern locations. Updates have been sent. UPDATE Issued at 626 PM CDT Sat Mar 25 2017 Have backed off on timing of precipitation chances over the southwest as rain appears to remain well off to the west and latest high-res models have slowed things down a bit. Otherwise, previous forecast looks good. && .SHORT TERM...(This evening through Sunday) Issued at 304 PM CDT Sat Mar 25 2017 At the upper levels, a west coast trough will keep the state in southwest flow through the short term. While the two most vigorous waves will pass to the north and south, there does appear to be enough convergence at the surface for some light precipitation along an inverted surface trough that will extend from western South Dakota into southwestern North Dakota overnight. Many of the High Resolution models are showing fog from east of the Missouri River valley to the James River valley. While, the HRRR specifically looks a bit overdone, the feeling is that at least patchy fog will be possible over these areas overnight and Sunday morning. Light precipitation chances will continue to propagate east through the day on Sunday bringing more chances of light showers to much of the forecast area. Over the James River valley, forecast soundings show a very brief opportunity of a light mixture of rain, freezing rain, and possibly sleet Sunday morning. .LONG TERM...(Sunday night through Saturday) Issued at 304 PM CDT Sat Mar 25 2017 Progressive flow aloft will keep the area in an active pattern, but split flow will keep any major chances of precipitation to a minimum. For now, the best chances for some light precipitation appear to be overnight Tuesday and into Wednesday morning. From there, model agreement tends to diverge with regards to wave strength and timing specifics. For this reason, elected to keep with our in house blend of global models throughout the long term. Above average high temperatures, generally in the 50s and 60s, will stick around through the extended period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 626 PM CDT Sat Mar 25 2017 Patchy fog will develop later tonight over central North Dakota into the James River Valley bringing localized IFR conditions. The fog will deteriorate Sunday morning. Some light rain is possible over southern areas overnight into early Sunday morning. Localized MVFR visibility will be possible. Otherwise...VFR conditions will prevail. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JJS SHORT TERM...ZH LONG TERM...ZH AVIATION...JJS
Area Forecast Discussion
National Weather Service Cheyenne WY
338 PM MDT Sat Mar 25 2017 .SHORT TERM...(This evening through Tuesday) Issued at 300 PM MDT Sat Mar 25 2017 Unsettled weather ahead through the next few days into next week. Forecast challenges deal with timing and location of precip. Currently...Cold front extends from eastern Montana, south to near Casper to just west of Rawlins, into northern Utah this afternoon. Showers confined to northwestern Wyoming on mosaic radar this afternoon. Pretty tranquil conditions over our county warning area this afternoon as skies continue to thicken and lower. afternoon temperatures running in the mid to upper 50s across the area. Front forecast to move into our western zones (Carbon County) after 00Z (5PM) today to Converse and Albany Counties near 06Z (11PM)and then into the northern Nebraska Panhandle and around Cheyenne by the 09-12Z (2-5AM) timeframe. Would expect these time to be when showers would begin to break out across the CWFA. HRRR simulated radar confirms this timing as the front moves through tonight. Not a lot of cold air behind this system. 700mb temperatures fall from +1 to +4C this afternoon down to -4C to -1C from west to east. Snow could develop in the valleys out west as this colder air moves into the area. As for eastern areas, do expect showers to remain all liquid. Not expecting much in the way of accumulations as QPF fields are fairly low on all the guidance forecasts. Looks like a cloudy/showery day for Sunday with highs in the 40s and low 50s from west to east. Best chances for precip looks to be late in the short term as our next Pacific low moves into northern New Mexico Tuesday afternoon. Given the performance of the guidance on our last low pressure system, will lean towards a low confidence forecast on snow accumulations and timing for now. .LONG TERM...(Tuesday night through Saturday) Issued at 300 PM MDT Sat Mar 25 2017 Tuesday night/Wednesday...Strong upper trough moves slowly across northern New Mexico with widespread rain and snow showers progged to spread west to east across our counties Tuesday night. After daybreak Wednesday, the upper low is forecast to track into east central New Mexico with ridging moving over our counties north of the low. In response, precipitation is expected to end from west to east during the day. Thursday...Transitory shortwave ridging aloft progged to move across our counties, producing a dry day with warmer temperatures due to more sunshine and a moderating airmass. Friday...Next vigorous closed low aloft progged to move southeast to near the Four Corners by late afternoon, while a cold front moves across our counties, with a chance of showers across most of our region. Cooler temperatures due to expected precipitation and extensive cloud cover. Saturday...The closed low is progged to continue moving southeast into southern New Mexico, a further south track than the previous weather disturbance, thus lesser chances for precipitation across our counties, especially in the afternoon when the bulk of precipitation and clouds associated with the upper low, is progged to move over Colorado. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 335 PM MDT Sat Mar 25 2017 Wyoming TAFS...VFR, except for MVFR at Cheyenne from 09Z to 15Z, MVFR at Laramie from 06Z to 15Z, and MVFR at Rawlins from 03Z to 15Z. Nebraska TAFS...VFR, except for IFR or MVFR from 11Z to 18Z. && .FIRE WEATHER... Issued at 300 PM MDT Sat Mar 25 2017 Unsettled weather for the upcoming work week. No fire weather concerns through the weekend. Minimum humidity values will mostly be above 25 percent this afternoon. Cooler temperatures along with a chance of rain and snow showers are expected on Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...RUBIN AVIATION...RUBIN FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Duluth MN
926 PM CDT Sat Mar 25 2017 .UPDATE... Issued at 926 PM CDT Sat Mar 25 2017 Clouds continue to expand north and west this evening with light precipitation moving through parts of northern Wisconsin. KPBH reported light rain for a brief period and area radars show weak echoes continue to move north. We don`t plan any big changes to the forecast at this time. There is some concern portions of Ashland and maybe even Bayfield Counties could get enough freezing rain to warrant an advisory. Temperatures were from 31 to 36 degrees across those counties and there may be a bit more of a drop but clouds continue to thicken. We will not add any more counties to the advisory at this time but continue to monitor radar/model/observations. && .SHORT TERM...(This evening through Sunday) Issued at 314 PM CDT Sat Mar 25 2017 Cloud cover is expected to increase again overnight tonight ahead of a stacked area of low pressure that will be situated over the mid Mississippi River Valley overnight. A lobe of PVA will eject from this low pressure system, along with increasing 850-700 mb layer warm air and moisture advection, will support increasing chances of precipitation over northwest Wisconsin this evening, and then from the Brainerd Lakes northeast towards the Minnesota Arrowhead Sunday morning. East to northeast on-shore winds off of Lake Superior will continue through the day Sunday, which should advect some cooler temperatures over land. This may lead to the development of some patchy fog along the North Shore. Confidence is not high that any dense fog will develop despite what a few of the models were progging, including the RAP and HRRR models, and to a lesser extent - the WRF ARW/NMM models. Cloud cover and stronger winds due to the favorable fetch should help limit the fog, but dew point depressions still look favorable. Due to the cooler temperatures being advected on-shore, still think some patchy fog is likely, but don`t think it will be dense. Therefore, introduced patchy fog over the North Shore overnight. The main concern for the overnight hours will be the precipitation types overnight. As the PVA and warm air advection arrives, the thermal profiles are expected to cool. Deepening moisture profiles, as indicated in the RAP/NAM model soundings, along with cooling sfc temperatures, will lead to mainly freezing rain across portions of northwest Wisconsin, with the possibility of snow/sleet mixing in. The most uncertainty for this forecast comes from the exact temperature profile as the sfc temperatures will be right at freezing. Any change in the sfc temperatures, either plus or minus a degree, will have big changes in p-types. The guidance is hinting at favorable sfc temperatures for freezing rain along the higher elevations of the Gogebic Range in Iron county. Due to the potential for a wintry mix, with freezing rain being the primary p-type expected, decided to issue a Winter Weather Advisory for Iron county tonight and into mid Sunday morning until temperatures warm up. Smaller changes of freezing rain are possible along the North Shore overnight as well, but the heaviest QPF is expected over northwest Wisconsin, so not expecting as much ice accumulation along the North Shore. Ice accumulation in Iron county could be up to a tenth of an inch, with the greatest amounts expected in the higher elevations of the Gogebic Range. Precipitation will transition to all rain late Sunday morning through the afternoon as the temperatures increase. Temperatures will remain near or above seasonal averages during the day Sunday, with decreasing chances of precipitation Sunday afternoon and evening. .LONG TERM...(Sunday night through Saturday) Issued at 314 PM CDT Sat Mar 25 2017 No major storms appear in the offing for the upcoming week, but there will be periodic chances for light precipitation, both at the beginning of the period, and again later in the week. At the beginning of the extended periods Sunday night and Monday, ongoing light precipitation will be winding down and ending as the slow-moving upper low over the middle Great Lakes region slowly pulls away to the east. As the eastern North American trof axis amplifies a bit early to mid week, high pressure will strengthen slightly over Canada, and should be sufficiently strong to push a weak surge of slightly colder air southward into the western Lakes region Tues-Wed. This should also be sufficient to minimize precip chances during this time with general large-scale subsidence. Beyond Wednesday, the medium range models have significant differences in both amplitude and timing of various weak disturbances that will affect the Northland through the remainder of the 7 day forecast window, which is also supported by the rather large spread in the ensemble solution space. The region should transition to a slightly warmer airmass with time, but there will also likely be periodic chances for light precip during the Thursday- Saturday time range, and it seems likely that there will be at least a couple of short time windows where light wintry mixed precip will be possible across the region. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 657 PM CDT Sat Mar 25 2017 Low pressure was located in central Missouri as of 23Z and moisture was surging northward. The low will move into the MO/IA/IL border by 12Z Sunday and a lobe of vorticity will move north into the Northland overnight. MVFR/IFR ceilings will expand to all areas overnight. Light rain or light freezing rain will also develop from southeast to northwest through the night, most widespread over northwest Wisconsin. There is still uncertainty whether or not KHYR will experience freezing rain later tonight. Temperatures did warm nicely this afternoon into the middle forties and clouds have moved back in which will cause temperatures to fall more slowly tonight. We kept a period of freezing rain from 09Z to 13Z in the latest TAF and will reevaluate with the next issuance. Rain or freezing rain may reach into portions of northeast Minnesota later tonight but confidence is lower there so we only have a mention at KDLH for now. Fog may also develop tonight and we did lower the visibility in some of the TAFS. && .PRELIMINARY POINT TEMPS/POPS... DLH 30 38 30 46 / 40 40 10 10 INL 29 47 28 48 / 0 0 0 10 BRD 32 45 32 54 / 30 20 10 10 HYR 33 42 31 48 / 60 50 30 10 ASX 32 39 30 45 / 60 50 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory until 9 AM CDT Sunday for WIZ004. MN...None. LS...Small Craft Advisory until 4 AM CDT Sunday for LSZ121-140>148. && $$ UPDATE...Melde SHORT TERM...JTS LONG TERM...Miller AVIATION...Melde
Area Forecast Discussion
National Weather Service Des Moines IA
651 PM CDT Sat Mar 25 2017 .SHORT TERM.../Tonight through Sunday/ Issued at 347 PM CDT Sat Mar 25 2017 The primary concern through the period will be precip trends. The parent upper low and its attendant short waves/PV anomalies continues to slowly advance through MO this afternoon and should only reach the IL/WI border by 18z Sunday. Our current deformation zone precip band should continue to slowly deteriorate into Sunday morning but not go away completely with precip just becoming more spotty as forcing becomes neutral to subsident as sufficiently deep moisture is less and less prevalent. Soundings suggest our moisture depth should stay in the 1-3km depth so patchy light rain or drizzle should be more common than steadier rain with persistent stratus in the broad cyclonic flow. The only exception to this may be SE this evening were weak convection is possible near the core of the upper low. Have mentioned some fog potential too as the latest ESRL HRRR, HRRR and RAP runs are all quite bullish. Do not expect anything dense however due to the steady blanket of stratus. The precip will likely end by Sunday afternoon however as the moisture layer shrinks due to mixing from below and drier air above. Temperatures should fall no more than several degrees tonight with little rebound Sunday either, especially north. SE sections may mix sufficiently to get well into the 50s however. .LONG TERM.../Sunday night through Saturday/ Issued at 347 PM CDT Sat Mar 25 2017 Monday... 20z Sat water vapor imagery clearly picking up on an upper low spinning near the four corners region of the SW CONUS. Now approaching 48 hours out, models have finally begun to come into agreement with one another...more or less beginning to cluster around the ECMWF (southern) track for the track of this low and the sfc reflection. Sfc low now slated to track through southern Missouri towards Kentucky. Subsequently, best forcing looks to be in Missouri, with a narrow ribbon of frontogenetical forcing near 900mb to 800mb barely clipping the 2 southernmost tier of counties in the DMX CWA. KOTM Bufkit soundings show pocket of dry air around 800mb to 650mb that will make notable precip growth difficult. Thus have kept QPF less than 0.05 inches, which even be too high yet. Tuesday and Wednesday... Sfc high pressure looks to fill in behind the Monday system. Models in good agreement with placing the high near the Minnesota/Canada border by 12z Tue, and by Lake Superior by 00z Wed. Aloft, zonal flow should remain in place, accompanied by a jet streak across Minnesota to Michigan, which should keep us under upper to mid-level cloud cover. Though strength of insolation not superb this time of year, depending on thickness of clouds, temps may need to be knocked down a few degrees. Thursday and beyond... Models continue wild variation with tracking of the next system. Most long-range models and ensembles now pick up on upper level low swinging through the TX/OK panhandle around 00z Thu. Tracing this low back to its source region, the low is picked up on water vapor imagery, and it should come onshore around 12z Monday. So, tonight`s 00z runs may not vary much...but hopefully the 12z Sun and 00z Mon runs should begin to have better resolution with the track of this system. 12z Sat long-range solutions holding firm/stubborn with their 12z Fri solutions. 12z Sat GEM has joined the ECMWF with the northern solution. In short, the 12z GFS places the sfc low over the southeastern CONUS at 12z Fri, the 12z Sat ECMWF places the sfc low over central Illinois, and the 12z Sat GEM actually places the low over southern Iowa. Regardless of location, warm sector side of low should be able to tap into gulf moisture...and support may be there for strong/severe storms. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 650 PM CDT Sat Mar 25 2017 Main concerns are cigs/fog and potential for light rain or drizzle. Old low continues to spin up showers or light drizzle over the area. Winds are expected to diminish slowly in the next 24 hours. Cigs remain IFR and likely to drop to LIFR at times again overnight. Fog is also beginning to develop over the southeast. Hires models suggest that fog will fill in over much of the south overnight. Confidence not high enough to lower visby to IFR yet over all of the south. May need to update with time if areal coverage expands. Conditions slow to improve Sunday but some improvement expected toward end of period. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Small LONG TERM...Kotenberg AVIATION...REV
Area Forecast Discussion...Correction
National Weather Service Fort Worth TX
1036 PM CDT Sat Mar 25 2017 .UPDATE... Main update was to include a mention of patchy fog for southern zones as well as adjust temperature and dewpoint trends during the overnight hours. Also, made a few slight changes to PoPs based on the latest arriving model output. Surface analysis this evening revealed that low level moisture was beginning to lift northward along the Upper TX Coast with the 00 UTC RAOBs indicating the 1" PWAT isopleth was slowly lifting northward. Closer examination of these RAOBs indicate that the moisture depth is about 1km or so suggesting that perhaps a slightly richer quality of moisture does exist. The 4-Corner`s upper trough will continue to pivot eastward and with subsequent lee-side pressure falls ongoing and forecast to continue, this plume of low level moisture should have little in the way to impede its progress through the overnight hours. With the increasing low level moisture, there`s a potential for some light and patchy fog mainly across Central zones. Farther north, northerly winds, due to the influence of the weak front/surface low across the Missouri Valley, will eventually become more easterly and southeasterly, but not before temperatures fall into the low 50s. If southeasterly winds do not occur before sunrise, it`s possible that temperatures along the Red River are not low enough. This front will have ramifications for PoPs on Monday morning and this is discussed below. With regards to Sunday`s severe weather potential, the threat still remains contingent on several factors. The first will be the degree of low level mixing that occurs as low level moisture lifts northward. RAP output indicates that low to mid 60 degree dewpoints will be possible along the Red River. This is somewhat interesting as the RAP typically mixes quite deeply and one would not expect such high dewpoints as far north as the Red River. Other model guidance, however, remains tightly clustered around a solution that places the 60 degree isodrosotherm a little farther south with mainly 50s along the Red River and I`ve trended dewpoints closer to this solution. This is important as even a minor change in surface dewpoints can result in the amount of instability and low level buoyancy to perhaps breach the cap. If the RAP is correct, there could be a bit more instability in place and a slightly weaker cap than is advertised at this time. With regards to the cap---a majority of hi-resolution and coarser guidance do weaken the cap sufficiently in the 21-00 UTC time frame near the Highway 281 corridor. With sufficient convergence along the dryline, we should see a few storms develop. Environmental parameters do support a supercell storm mode. With an unseasonably warm and well mixed boundary layer, LCLs will likely remain high which would foster more of a damaging wind and large hail potential. If the quality of moisture is a bit better and can resist being scoured out completely, LCLs would in theory be lower. This combined with an environment characterized by favorable turning of the low level winds (large hodographs) does mean that a slightly greater tornado threat would materialize should the low level moisture quality be a bit higher than currently thought. This is something that we will closely monitor with additional model output and a new suite of upper air data Sunday morning. With that said, I nudged PoPs upward by a hair and extended them a bit farther south and west along the axis of greatest instability and weakest inhibition for Sunday afternoon. As has been stressed the past few days, the probability for numerous severe storms is low (likely just a handful at best), but should storms get going, they will more than likely become severe. The most likely area for strong ot severe storms will be generally along and north of I-20. The only other change in the forecast was to add a low chance for showers and storms Monday morning across eastern/southeastern zones. As the upper forcing slides eastward, it appears that a cold front will overtake the dryline. Various NAM solutions continue to produce QPF. With the forcing and expected low level moisture in place, I went ahead and added a sliver of 20 PoPs out across eastern zones. The remainder of the forecast looks to be in good shape. 24-Bain && .AVIATION... /ISSUED 620 PM CDT Sat Mar 25 2017/ Winds will become light and variable toward sunset and then southerly later during the evening as a surface high moves off to the east. Low clouds and areas of fog are expected to develop across South Texas overnight tonight and some low clouds may spread north into the Waco area by 12z and into the Metroplex TAF sites after daybreak. Thus have indicated a TEMPO BKN015 at KACT from 12 to 16z and a TEMPO BKN020 at the Metroplex TAF sites for the 13 to 16z period. Southerly winds will be on the increase Sunday as a lee side trough deepens. Expect south winds 10-12 knots at 13z to increase to 15-17 knots by 16z with some gusts of 25 knots possible through the afternoon. Although a capping inversion will be in place, isolated to scattered thunderstorms may form along the dryline by mid afternoon along and north of the I-20 corridor. Thus have placed VCTS in the Metroplex TAF sites for the 21z through 00z period. 58 && .PREV DISCUSSION... /ISSUED 400 PM CDT Sat Mar 25 2017/ Mostly sunny skies and pleasant temperatures prevail across North Texas behind last night`s cold front. West-northwest winds have ushered in some drier air making for a nice day across the region. Temperatures are generally in the 60s and 70s with dewpoints in the 40s. Springtime usually means rapidly changing weather as the upper pattern is usually fairly progressive. Tomorrow will be no different. Shortwave ridging today and tonight will give way to a fast moving shortwave trough by tomorrow and increasing severe weather chances. As the upper disturbance approaches, rapid surface cyclogenesis will commence during the morning hours. This will result in strengthening southerly flow and a rapid northward transport of moisture. By midday, surface dewpoints will likely be near 60 degrees along the I-35 corridor toward to the Red River. In addition, a dryline will advance eastward across West- Central Texas. By late afternoon, an elevated mixed layer will be in place across North Texas resulting in a capping inversion around 800mb with very steep lapse rates through about 500mb. Even as the main shortwave tracks across northern Oklahoma, stronger forcing for ascent will spread into North Texas by late afternoon. This should help to lift the capping, which is not expected to be overly strong. We`ll likely sample this with supplemental balloon data tomorrow afternoon. The bigger concern regarding convective development will be the quality and depth of moisture return into the area given the northerly track of the shortwave. Surface based instability is expected to be around 2000 J/kg with dewpoints in the lower 60s, although this moisture is fairly shallow. Mean layer instability (around 1500 J/kg) will likely be more representative of the environment tomorrow afternoon from the Metroplex and areas southward. Most of the high resolution guidance develops convection to the west-northwest of the Metroplex by 22Z, although these initial convective attempts quickly diminish by 00Z. This suggests that the initial development along the dryline may not have enough support to allow them to move off the dryline into a more unstable environment. Forcing will be stronger the farther north, so areas generally north of I-20 should have a better chance for thunderstorms through the early evening hours. Our latest thinking is that the best chance for severe thunderstorms in our area will be in the Red River counties, particularly Cooke, Grayson, and Fannin counties, from about 22Z to 00Z. However, it should be noted that if any storms farther south can be sustained, then the environment is more than suitable to support severe weather. Forecast soundings for tomorrow afternoon feature lapse rates in excess of 8 C/km through a deep layer along with large clockwise curved hodographs through the lowest 2 km. While all modes of severe weather will be possible, the quality/depth of moisture remains the biggest limiting factor for a more appreciable tornado threat. Very large hail (baseball size or larger) will be the main severe weather threat through the evening hours. We`ll maintain 20-30% PoPs across mainly the northern half of the CWA with the best chances along the Red River. Any convection that develops will move east through the evening with a cold front moving into the area during the overnight hours. Monday looks like it will be a rather nice day behind the cold front but it won`t last long. Another strong upper low will move into the southwest U.S. by Tuesday. This will again allow moisture to spread northward and rain/storm chances increasing late Tuesday through Wednesday. There may be an initial severe weather threat late Tuesday afternoon/evening as convection develops across West Texas along a dryline and moves eastward. Rain/storm chances increase significantly across North Texas Tuesday night into Wednesday where one or more rounds of thunderstorms may move through the region. At this time, the severe weather threat does not look overly impressive, although there will be sufficient instability/shear to support rotating storms during this time. We`ll monitor this closely over the next 48 hours. Heavy rainfall will be possible through Wednesday with current forecast rainfall amounts between 2 and 4 inches across parts of North Texas. While the system looks like it will remain progressive enough to preclude a more significant flash flood threat, localized training of storms would support flash flooding. This system moves east Wednesday night into Thursday with quiet weather through the end of the week. Dunn && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 55 84 60 80 56 / 0 30 20 5 0 Waco 54 83 62 83 59 / 0 20 20 5 5 Paris 50 80 60 77 53 / 0 10 50 5 0 Denton 51 82 58 78 53 / 0 30 20 5 0 McKinney 49 81 59 78 54 / 0 30 30 5 0 Dallas 55 84 62 81 57 / 0 30 30 5 0 Terrell 50 82 62 79 56 / 0 20 40 5 0 Corsicana 54 84 63 82 60 / 0 20 30 10 0 Temple 57 84 60 84 60 / 0 20 10 5 5 Mineral Wells 52 86 54 80 53 / 0 20 10 5 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$ 58/24
Area Forecast Discussion
National Weather Service Hastings NE
1058 PM CDT Sat Mar 25 2017 .UPDATE... Issued at 1058 PM CDT Sat Mar 25 2017 Updated to add drizzle to the forecast tonight. UPDATE Issued at 824 PM CDT Sat Mar 25 2017 Updated the forecast to introduce areas of fog earlier this evening for much of the CWA on the NE side. Visibility has been jumping around, but am a bit nervous that we might need a Dense Fog Advisory considering GLAMP and MOS data, and also HRRR model. JYR dipped to 1/2SM mile for awhile, but has since come up to 2 SM. Will keep monitoring trends, but for now, will hold off on any Dense Fog Advisory as we are not clearly tanking as of yet. && .SHORT TERM...(This evening through Sunday) Issued at 231 PM CDT Sat Mar 25 2017 High Impact Weather Potential: Fog likely late tonight thru Sun AM and it has potential to be dense (1/4SM vsbys or worse). Aloft: A slow-moving low was over MO and a shortwave trof was advancing thru the SW USA. This trof will kick the low NE tonight with the intervening ridge moving over the fcst area (FA). The trof will arrive tomorrow and track across the Srn Plns with a small low moving E across KS. Surface: The low pres sys that moved thru the last couple days to the E. An axis of the high over Ontario/Quebec extended SW across Neb into CO...while a cool front was making its way thru the Wrn USA. High pres will remain overhead tonight. The front will cont E with lee cyclogenesis occurring along the NM/CO border. The newly formed low will head E tomorrow into Nrn TX. The Nrn portion of the front will weaken and move into the FA as an inverted trof. Now thru sunset: Mainly cldy...dry and chilly except over the Wrn fringe of the FA where some sun has been/is occurring. Tonight: Cldy/foggy. Areas that have seen the sun W of Hwy 183 will cloud-up. E-NE winds will advect the stratus W and this is shown by all hi-res models. Conds are ripe for fog. Low stratus has lingered thru the day for most of the FA...keeping temp-dwpt depressions low and BL flow is from the NE where it has been raining today...meaning that incoming air is very moist. There is potential for dense fog...but there are a couple mitigating factors that reduce confidence: 1) the invasion of thick multi-layered mid-high clouds from the W which will reduce radiational cooling. 2) Where stratus remains locked in...does it build down low enough for 1/4 SM vsbys? Sun: Cldy/foggy thru the AM and the low clds will probably last well into the day. They will be hard to get rid of with contd E-NE low-lvl flow. Expect some erosion/dissipation will occur W of Hwy 281...but even still it will only reveal multi-layered mid-high clds. Used consensus of model 2m temps for high which does well in these situations. That kept areas N and E of the Tri-Cities the coolest. A bit of -RA will move into the SW 1/3 of the FA after 3 PM on the N side of the low moving acrs KS. .LONG TERM...(Sunday night through Saturday) Issued at 231 PM CDT Sat Mar 25 2017 High Impact Weather Potential: None currently envisioned outside of probable aviation concerns with IFR conds expected Wed-Thu. We have are currently in a window of opportunity for increased legitimate precip chances and it will last for about the next 10 days before ensemble means hint at a return to NW flow. Aloft: A shortwave ridge will move thru Mon ahead of the next trof moving onshore and digging into the Desert SW. The flow aloft will turn SW Tue as a newly formed low progresses from AZ into NM. It is a good sign that this low is fcst to be a slow-mover ...lifting into the TX panhandle Wed and then across KS Thu to be somewhere near MCI by 00Z/Fri. As is predecessor...this low will get kicked NE as another low forms over the Wrn USA and drops into the Desert SW Fri. So a ridge should be overhead Fri. There are indications from the last 2 runs of the GEM/EC/GFS that this low might cut-off over the Mex-AZ-NM border. But the EC ensemble mean suggests it could lift NE into the Plns as well. Plenty of time btwn now and then to iron out the details. Surface: Canadian high pres will cont to nose S into the FA Mon- Tue while the next Pac cool front progresses thru the Wrn USA. But cyclogenesis will commence over NM. This low too will head E across the Srn Plns Wed-Thu and then head toward the GtLakes Fri. An inverted trof N of this system will move into the FA Tue night. Weak high pres will slowly build into the rgn Thu-Sat. Precip: The shield of RA will move out Sun night...mainly affecting N-cntrl KS. Parts of the FA have the potential to get drenched with more much-needed rainfall Wed-Thu. Amts depend on where the def zone sets up and pivots or become stationary for a while. Still no thunder in the fcst. We`d need a diff track. Can`t entire full out a strike or two...but evidence is not strong enough that sufficient instability will exist. Temps: Near normal Sun. A little above normal Mon-Tue. We are probably too high Wed-Thu with periods of RA and heavy/thick cloud cover. These days should both be cooler than normal. Fri-Sat back to near normal. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Sunday evening) Issued at 652 PM CDT Sat Mar 25 2017 Biggest challenge will be determining how fast visibility decreases tonight. Observation from KGRI just came in at 2 1/2SM, so I might very well need to update soon. Numerical models indicate that ceilings should continue to low as stratus works its way toward the surface, and expect LIFR ceilings by overnight, along with fog developing as well. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Heinlein SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Heinlein
Area Forecast Discussion...UPDATED
National Weather Service Grand Junction CO
801 PM MDT Sat Mar 25 2017 .UPDATE... Issued at 801 PM MDT Sat Mar 25 2017 Latest satellite imagery shows the upper level trough and cyclonic rotation moving east-southeast across southern UT. Lightning has been active under the center and to the east and south of the trough and was observed as far north as just west of Canyonlands Airport in the last hour. One band of clouds and associated virga pushed north over western CO and eastern UT late this afternoon and early this evening and helped to moisten up the lower levels. Light rain has been observed at many locations along and north of I-70 in the last couple of hours and snow was observed at 10,000 feet on Hwy 65 over the Grand Mesa. Cooling cloud tops continue to expand ahead of the base of the trough over the Four Corners and toward the San Juan Mtns. Latest RAP model indicates best and highest precip chances over the San Juans and toward the NM border between 10 pm and 4 am. During this time the snow level will also be dropping to near 8000 feet, before dropping possibly as low as 6500 feet by sunrise. The Winter Weather Advisory looks on track for 4 to 8 inches above 9500 feet and lesser amounts at the lower elevations. Forecast has been updated to support current and near term trends, especially to increase PoPs across the southern areas. A pretty sharp back edge to the mid to upper level QG forcing should bring an end to the significant precipitation by sunrise. && .SHORT TERM...(Tonight through Sunday night) Issued at 144 PM MDT Sat Mar 25 2017 A fast moving and vigorous Pacific storm was tracking eastward across the Desert Southwest spreading clouds over the forecast area. Radar hadn`t detected more than an area of virga over eastern Utah`s Grand Flat region so far this afternoon, but that should change as the system draws closer. The latest forecast models take the open wave trough eastward across the area tonight. The bulk of the energy associated with the trough will pass just south of the Four Corners from late this evening into the early morning hours. A nice Div-Q couplet in the base of the trough combined with divergence aloft and orographic lift favors precipitation over the San Juan Mountains. Dynamics may be sufficient to generate isolated thunderstorms over portions of southeast Utah and southwest Colorado. QPF output from latest models higher than previously forecast and doesn`t seem unreasonable, though there may be some convective feedback in the NAM12 solution. Consequently, boosted QPF numbers in the San Juan Mountains with this package which increased snow amounts to low end advisory amounts. Limiting factor with this event will be the warmth ahead of the trough which will limit accumulations this evening, and the short duration of this event. Temperatures suggest the snow level will be near 9500 feet at 6 PM this evening, but will lower to near 6500 feet around sunrise on Sunday. As a result, significant accumulations are likely to be limited to areas above 9500 feet, or from 4 to 8 inches with locally higher amounts, and from 1 to 4 inches from 8000-9500 feet, and from trace to an inch from 6500-8000 feet along the slopes of the San Juan Mountains. Given the previous, hoisted a winter weather advisory for the San Juan Mountains above 9500 feet from 6 PM this evening through 9 AM Sunday morning. Main concern is snow impacts on the high passes where road conditions will deteriorate and visibility will become limited. Surrounding mountain areas will also see snow, but accumulations will largely range from 3 to 5 inches with locally higher amounts on top of the Grand Mesa and into the Sawatch and West Elk ranges. Instability showers will continue along the Continental Divide Sunday, but additional accumulations are expected to be light and localized. Diurnal cooling and drying will bring an end to shower activity Sunday evening. Forecast lows tonight should be milder due to cloud cover. An influx of cooler air will bring afternoon highs down a few degrees Sunday, but temperatures will remain above normal. Colder temperatures are on the horizon Sunday night, though freezing temperatures in areas where tender vegetation has budded is unlikely. .LONG TERM...(Monday through Saturday) Issued at 144 PM MDT Sat Mar 25 2017 As mentioned in previous discussions, the progressive spring pattern will continue during the coming week. After a brief break in activity showers and embedded thunderstorms are expected to develop over much of the region Monday afternoon ahead of the next Pacific storm. Latest models were in much better agreement with the evolution and track of this system. From late Monday afternoon through Tuesday morning, models deepen the trough over the western Great Basin forming a closed low over central Arizona. From there, the low center drifts slowly eastward arriving over the Texas Panhandle Wednesday afternoon. During this period the forecast area will fall under the col area between the storm to the south and the northern atmospheric stream. As a result, expect unsettled conditions to continue through Tuesday night with isolated thunderstorms during the afternoon. Mountain snow accumulations may be sufficient for additional winter weather advisories during the early part of the week. A transient ridge will allow a return to quiet weather Wednesday and most of Thursday. Thereafter, another closed Pacific low pressure system will begin to impact the area. Model agreement isn`t as good as with the system discussed previously for the early part of the week, so difficult to sort out the details with this next storm with much confidence. At this point it seems fair to expect unsettled conditions during the latter part of the week. Expect a bit of roller coaster where temperatures are concerned, but variances aren`t expected to be profound from one day to the next. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 503 PM MDT Sat Mar 25 2017 Mostly cloudy skies and plenty of virga seen across the area this afternoon. Scattered rain and snow showers have also already developed, generally confined to the higher terrain ATTM. Showers will increase in coverage and spread into some valleys into the evening with the best chance tonight through Sunday morning as a disturbance tracks across the region. The San Juans will be favored during this event with periods of reduced cigs and vis and obscured mountain tops overnight. Lower valley TAF site cigs should stay above ILS breakpoints but higher TAF sites like KASE and KTEX will drop down to MVFR or even IFR at times during heavier showers. Activity will decrease after 18Z tomorrow with just some lingering orographic showers as drier air works back into the region. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until 9 AM MDT Sunday for COZ018-019. UT...None. && $$ UPDATE...BM SHORT TERM...NL LONG TERM...NL AVIATION...MMS
Area Forecast Discussion
National Weather Service Green Bay WI
1006 PM CDT Sat Mar 25 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 225 PM CDT Sat Mar 25 2017 The latest RAP analysis and satellite/radar imagery show an area of low pressure spinning along the Kansas/Missouri border, and an associated warm front extending eastward across central Illinois to northern Pennsylvania early this afternoon. Band of light rain north of this boundary has been creeping northward across southern Wisconsin, and should reach the southern Fox Valley later this afternoon. Meanwhile, a potent Canadian high pressure system has been feeding dry air into northern WI, which has kept temperatures in the 30s. Though partial clearing has pushed its way into northern Lake Michigan, widespread overcast conditions continue. As the low pressure drifts northeast over the next 24 hours, precip trends and potential for freezing rain across northern WI are the main forecast concerns. Tonight...Occluded low pressure will slowly chug its way northeast across the central Mississippi Valley while a strong Canadian high will exit over Quebec. The waning influence of the high will allow for increasing moisture transport from north to south across the state during the evening, highest over eastern WI within the warm conveyor belt. Ample dry air in the mid-levels will keep the precip at bay across the north until late in the evening or early overnight, but the most persistent precip will occur over eastern WI. Despite the late arrival of the precip, the threat of freezing rain remains over north-central WI. Dewpoints didnt fall off much this afternoon, so temps should not fall much due to evaporative cooling. However, even with min temps in the 30-32 degree range, not comfortable going without a freezing rain advisory tonight across the north with precip amounts upwards of a tenth of an inch. With coordination from MQT will hoist an advisory from late this evening until 9 am Sunday morning. Sunday...The low pressure system will continue to drift closer to the region into the southern Great Lakes. Though the main slug of moisture shifts towards the lower peninsula of Michigan during the day, progged soundings continue to look saturated at most locations during the morning, which should be good for occasional light rain and drizzle. The chance of precip should diminish some during the afternoon from west to east as the deepest saturation exits to the east. With the widespread clouds, rain, and northeast to north winds, temps should only rise into the upper 30s to middle 40s. .LONG TERM...Sunday Night Through Saturday Issued at 225 PM CDT Sat Mar 25 2017 As the current low pressure system delivering precipitation to Northeast Wisconsin moves northeast through the Great Lakes and out of the region, another low will sweep by to our south. This second low will move east into the Ohio Valley during the first half of the work week and is not expected to deliver much, if any, precipitation to Northeast Wisconsin. Some cloudiness is possible, but skies should become mostly clear for the latter half of Tuesday and most of the day Wednesday. The next low pressure system to impact Northeast Wisconsin will develop over the Southwest U.S. on Wednesday and move into the Midwest by Friday. This system has potential to deliver heavy rain to our area at times into next weekend as it phases north. The low will not be particularly effective at tapping cold Canadian air, so precipitation should remain liquid for the most part. Any freezing rain should be limited to Northern counties during nighttime hours when coldest temperatures occur, producing scattered slippery spots. && .AVIATION...for 06Z TAF Issuance Issued at 1006 PM CDT Sat Mar 25 2017 Ceilings and visibilities lowering as expected across the far north as scattered rain has moved in. Some surface icing possible over far northern WI, including RHI, as temps near freezing in spots. IFR conditions will continue through late Sunday afternoon. Some improvement in cigs expected Monday as somewhat drier air moves in. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM CDT Sunday for WIZ005-010>012. && $$ SHORT TERM.....MPC LONG TERM......ML AVIATION.......JKL
Area Forecast Discussion
National Weather Service Wilmington OH
958 PM EDT Sat Mar 25 2017 .SYNOPSIS... Southerly flow ahead of low pressure will provide warm temperatures and mainly dry weather this afternoon. Showers and a few thunderstorms will develop tonight through Sunday as the area of low pressure approaches from the west. Another upper level disturbance will then move across the area Monday afternoon into Tuesday providing a continued chance of showers and thunderstorms for the area. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A weakening area of showers stretching from central Indiana into central Kentucky has been progressing very slowly eastward this evening. The latest HRRR is showing this pcpn continuing to weaken as it spreads into our western areas tonight. A better chance of showers will work into our southwest late tonight ahead of a stronger vort axis that will pivot up toward our area. Have made some tweaks to the pops to slow down the pcpn a few hours. Instability will be marginal at best overnight and this should help limit any thunder. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... Later Sunday morning the upper level low will take on a negative tilt as it pulls northeast towards the Great Lakes. As this happens low level temperatures will fall and work together with daytime heating to steepen low level lapse rates. NAM forecast soundings are showing MUCAPE values around 1000 J/kg while the GFS is showing values slightly higher, around 1200 J/kg. At the same time areas of PV will be rotating around the upper level low providing a source of lift. In general, global and high res models are indicating the best lift across our eastern zones Sunday afternoon with a secondary source of PV in association with the low moving into the western zones. Forecast soundings on both the NAM and GFS have k index values in the low 30s Sunday afternoon with LI values briefly turning negative. PWATs at this time are also around 1.00". Due to the ample moisture, sufficient lift, and instability have kept likely PoPs or greater for Sunday afternoon. It should also be noted that at this time 0 - 3km bulk shear is around ~30kts. Thanks to the shear, instability, low level lapse rates SPC has the area in a marginal risk for isolated small hail and gusty winds. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... Showers and thunderstorms will taper off Sunday night as an upper level disturbance moves to the east. There will be a lull in the precipitation for much of the day on Monday before an upper level disturbance moves through Monday night into Tuesday. Precipitation will taper off Tuesday night. Moisture will be trapped across the area for Wednesday therefore increased sky cover and decreased temperatures some for Wednesday. The next system will begin to bring rain shower chances to the region on Thursday. Precipitation is expected to become more widespread Thursday night into Friday as a low pressure system nears the region. A cold front will move through Friday night. Precipitation chances will begin to decrease after the passage of this feature. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... The leading line of showers and embedded thunderstorms is currently stretching from central Indiana down into central Kentucky. This line has been making a very slow eastward push and as we start to lose some of the diurnal heating, expect to see some weakening as it finally pushes into our western areas later this evening. As a result, will just allow for a vcsh late this evening and into the early morning hours at the western taf sites. A stronger mid level vort axis will rotate up across the area from the southwest late tonight into Sunday morning, eventually allowing for more widespread showers to develop from southwest to northeast. This should also allow for cigs and possibly vsbys to trend down into MVFR as we progress through Sunday morning. Instability remains fairly limited through the morning hours so think thunder chances will remain low enough to leave mention of thunder out of the TAFS through the morning. As we better destabilize through the afternoon hours, will go ahead and include a vcts to cover the thunder threat. OUTLOOK...MVFR ceilings and visibilities will be possible late Monday into Tuesday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines NEAR TERM...JGL SHORT TERM...Haines LONG TERM...Novak AVIATION...JGL
Area Forecast Discussion
National Weather Service Jackson MS
927 PM CDT Sat Mar 25 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... Things are beginning to quiet down following an active morning and afternoon across much of the area. Latest surface analysis shows a cold front centered along the MS river and slowly moving east. Meanwhile, a closed mid- and upper-level low was centered over central MO with the an associated trough axis oriented through the lower MS river valley. After this morning`s squall line moved through the atmosphere was able to destabilize enough ahead of the approaching cold front to support additional thunderstorms mainly north of I-20. Enough shear was juxtaposed with a tongue of diurnally enhanced instability for isolated supercell structures to be realized with an attendant hail and wind threat through the late afternoon hours. However, this activity has quickly weakened following sunset and a loss of diurnal heating. As of 2z, a few scattered showers and thunderstorms remain oriented SW to NE from TVR to CBM. For the remainder of the overnight period, expect this scattered shower and storm activity to continue to move east with the main focus for a shower or two becoming more oriented across the SE portions of the CWA. Any lingering lightning should dissipate quickly as convection continues on a downward trend. Our attention now turns to the potential for fog development across a good portion of the CWA. Latest hi-res guidance is fairly aggressive with low visibilities, especially across the SE, however confidence is not as high right now given that 1) there`s lingering cloud cover, 2) winds could stay just high enough to limit widespread dense fog, and 3) exact location of the cold front. Given these uncertainties will hold off on mentioning fog in the HWO for now and will keep patchy dense fog wording in the SE with regular patchy fog elsewhere ahead of the front and will let the next shift monitor the trends for future updates. In terms of min temps, went a degree or two cooler in the NW for areas that have the best chance of cooling behind the front and kept temps more mild everywhere else. /TW/ Prior discussion below: Tonight and Sunday: Visible satellite imagery this afternoon showing cold core low spinning about over the northern Ozarks. Meanwhile, down in our neck of the woods, the majority of this morning`s convection has moved to the east and southeast, but other storms have developed lately over north and west central sections of MS. These storms are developing in a confluent area of mid 60s dewpoints that have combine with heating to produce CAPEs around 1000 j/kg. Some of these have had robust updrafts and have produce some hail. The HRRR is showing these storms maintaining themselves for the rest of the afternoon with the possibility of a few more severe storms. Also, the convective area over the southeast looks to spread out to the northeast before moving into AL this evening. and only a few light showers left by midnight. With low level moisture hanging around overnight, fog looks like a good bet after midnight as skies clear. Surface winds never drastically change directions, thus southerly flow Sunday will begin quickly reloading the moisture levels in the lower levels ahead of a storms system slated for Monday. Low to mid 60s dewpoints look to overspread the area by 12Z Monday./26/ Monday through Friday: A generally active weather pattern will remain in place through the remainder of the forecast period thanks to a progressive upper level pattern. The next system of interest is still on track for Monday, as a mid level shortwave and surface low track across the Mid South. Moderate instability is expected across our area, along with decent height falls occurring with the passage of the wave. Given the timing of the system (peak heating/instability) and anticipated steep lapse rates, a respectable severe weather threat will exist with somewhat greater potential farther north in the area closer to the better forcing. The currently advertised slight/marginal risk areas may need to be tweaked upward in later forecasts for some portions of the area. The surface baroclinic zone associated with Monday`s system will stall just north/northwest of the CWA, keeping most or all of the forecast area in a warm/moist environment into the middle portion of next week. This will keep lower end chances for less organized showers/storms around Tuesday into Wednesday even as shortwave upper ridging passes across the area. The next system of interest is still on track to arrive around the Thursday time frame. Some model inconsistencies exist with respect to the nature of this system (slower moving cut off upper low vs more progressive upper wave). Nevertheless, the soupy airmass will remain in place ahead of this system, and another increase in rain/thunderstorm chances appears to be a good bet. Stronger deep layer shear will accompany this system, and there are indications that steep lapse rates will once again be possible. Particularly once we begin to see better model consistency, there is a good chance that severe potential will need to be added to HWO and graphics products for this period of the forecast. There is a better chance of an actual frontal passage with the late week system, suggesting a break in the rain is possible by next weekend. /DL/ && .AVIATION... 00Z TAF discussion: A line of tsra continued from nw of HKS ne across GTR at 2330Z. This line wl dissipate by 01z but an isolated shra or two wl remain possible over east MS tonight. Elsewhere, mostly clr skies wl allow fog development reducing vsbys to MVFR after 06z and IFR/LIFR by 11Z, especially over se MS. VFR conds are expected Sunday after 15Z and wl prevail into Sunday evening. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 60 82 63 82 / 26 3 9 58 Meridian 59 83 63 81 / 30 15 8 37 Vicksburg 55 82 63 82 / 27 2 7 58 Hattiesburg 61 84 64 82 / 30 14 8 28 Natchez 60 83 64 82 / 19 3 7 47 Greenville 52 79 63 78 / 1 2 15 61 Greenwood 56 79 62 80 / 5 2 12 63 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ TW/DL/22/26
Area Forecast Discussion
National Weather Service Blacksburg VA
1033 PM EDT Sat Mar 25 2017 .SYNOPSIS... High pressure is off the coast in the western Atlantic, stretching back across the southeastern states. A deep area of low pressure will drift east over the Midwest tonight with a trailing cold south into Louisiana. A warm front will reside from the Great Lakes region to Lake Erie into Sunday. && .NEAR TERM /THROUGH SUNDAY/... As of 955 PM EDT Saturday... Satellite fog product showed some breaks in the high clouds over the mountains this evening. Seeing some low clouds forming on the eastern slopes of the Blue Ridge as far north as Watauga and Wilkes county. Models showed these lower clouds expanding northeast after 06Z/2AM. HRRR and other Hi-Res guidance have been consistent in bringing higher probability of precipitation into the mountains around 12Z/8AM. Have trimmed back chance of showers before then. Also adjusted low temperatures in a few locations mainly based on the expected cloud cover. An upper level ridge off the southeast coast will continue to play blocker and divert a closed low over the Midwest toward the Ohio Valley through Sunday. Meanwhile, a dry surface high pressure system has moved off into the western Atlantic, however it remains stretched back over the southeastern US. The combination of these two stable high pressure systems will keep the area dry into tonight. As the closed low enters the Ohio Valley tomorrow morning, prefrontal showers will slowly move eastward through the day. Rain showers will cross over the mountains in the morning, then over the foothills in the afternoon. By late afternoon and into the evening, these showers will track across the piedmont. Lingering stable surface high will still cover the area east of the Blue Ridge in the morning and into parts of the afternoon. This will limit storms from becoming to strong in the afternoon and reduce rainfall amounts. Some wind gusts up to 35 mph are possible in isolated stronger storms but chances are very low. Southerly flow around these systems and a slower entry of showers into the area will help Sunday temperatures warm into the lower to mid 60s across the mountains. With the later arrive of rain east of the Blue Ridge, temperatures will be able to warm into the low to mid 70s. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 330 PM EDT Saturday... Upcoming week will be active nationwide as series of Pacific Low pressure systems propagate east across the CONUS. Leading system will be weakening as it moves northeast around the periphery of an upper level ridge of High pressure over the western Atlantic early Monday. A second shortwave will be close on the heals of the first, passing across the area Monday night into Tuesday. The overall result will be a threat for showers and isolated thunderstorms across our region from Sunday night through Tuesday night...qpf averaging about a quarter to a half of an inch. In spite of the weather being somewhat unsettled, it will be mild with temperatures running about 15 degrees above normal. Can`t rule out a strong thunderstorm or two Monday, but overall dynamic support appears to be lacking for anything organized. Tuesday`s trough passage may come through early enough to preclude an organized severe threat for our CWA, except for maybe the Piedmont. Instability and moisture are significantly more abundant Tuesday compared to Monday, but favoring the Piedmont and Tidewater where there will be higher CAPE and and better dynamic support aloft. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 400 PM EDT Saturday... Behind the Tuesday system, we will see a brief respite from the parade of storm systems as an area of high pressure from Canada filters southward into the area stabilizing and cooling the air mass. This should lead to a relatively precipitation free and slightly cooler period. Cannot completely rule out some light showers due to weak ripples in the flow aloft. Temperatures and dewpoints will drop about 10 degrees from the Mon-Tue period. By Friday, the next, and fairly potent, upper low tracks toward the area. However, there is considerable discrepancy between the GFS and the ECMWF in the configuration and timing of this system into the eastern U.S. The GFS depicts more of an open wave reaching the CWA as early as Thursday night moving east of the area by Friday afternoon. Meanwhile, the ECMWF is much slower, deeper, and further south with a cutoff upper low lifting it slowly north-northeast into the Ohio Valley by late Friday. The difference between the two models can be accounted for in noting the strength and blocking of an upstream ridge across the Atlantic. This upstream ridge is much stronger per ECMWF, which also depicts a notable wedge down the east side of the Appalachians as the closed low lifts north into the Ohio Valley. The ECMWF would result in a much wetter and stormier pattern for the CWA, although it would not arrive until Friday as opposed to Thu night per GFS. For now, have generally broad brushed the area with high chance to likely pops beginning Thu night and continuing into Friday. In addition to the differences noted above, there are also massive differences between the two models regarding instability and the potential for severe, with the ECMWF much more noteworthy in this category. For now, have included a chance for thunder without any further details. It will likely take several runs for the models to resolve their differences on this system. Another system is slated to follow by the end of the weekend or the beginning of the next week, so the active pattern is expected to continue into the next week. Temperatures will be closer to normal Wed-Thu, then begin to trend back to above normal levels Fri-Sat. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... As of 709 PM EDT Saturday... Generally VFR through the TAF period. For tonight, expect a continued stream of cirrus clouds for the terminals. If there is an area of lower MVFR stratus it would be along the southern Blue Ridge into northwestern North Carolina after 05z given increasing moisture levels and winds backing to light southeasterly. That would lead to obscured mountain ridges, but confidence is low that such cloudiness would affect either Roanoke or Danville. South winds 6-8 kts become southeast 3-6 kts overnight. Expect increasing BKN/OVC VFR cloudiness early Sunday morning, building eastward from west to east. Appears per recent high- resolution guidance that the earliest that showers would affect our western airports would be during the afternoon (after 17z). Potential for isolated thunder in the showers as well but only limited coverage. Left out of the TAFs given uncertainty at this late range. Ceilings/visibility should remain VFR, though potential brief MVFR visibility in steadier showers. Southeast winds Sunday morning increase and become southerly 6-10 kts. Extended Aviation Discussion... An active weather period with a series of vigorous upper-level low pressure areas tracking from west to east across the U.S. during the week. Showers and a few thunderstorms will overspread the area Sunday with the first system with widespread sub-VFR cigs/vsbys in clouds and precipitation. Monday the area will be between systems, but a moist/unstable air mass will remain in place and widely scattered showers and isolated thunderstorms are possible. Areas of sub-VFR cigs/vsbys are also possible, especially during the morning hours, in low clouds and fog. The next upper-level low will arrive Tuesday with another chance for showers and thunderstorms along with periods of sub-VFR conditions. Wednesday-Thursday may bring a period of improved aviation conditions as a weak cold front temporarily pushes the deeper moisture south of the area. However, by Friday the next in the series of upper-level systems arrives with another chance for showers, thunderstorms, and sub-VFR conditions. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...RCS NEAR TERM...AMS SHORT TERM...PM LONG TERM...RAB AVIATION...AL/RCS