Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/18/18

Area Forecast Discussion...Updated
National Weather Service Billings MT
817 PM MST Sat Feb 17 2018 .UPDATE... Snow has filled in west and north of Billings. Web cams showing snow coming down at a pretty good pace from Reed Point to Big Timber to Judith Gap to Roundup. Have adjusted PoPs and snow amounts slightly to account for radar and model trends. Added northern Stillwater county to the Advisory based on above. Other updates made earlier this evening look on track. Winds have picked up at Livingston and were now just below Advisory criteria. Expect an continued uptick in winds through the early overnight hours, then dropping off toward morning. Advisory there in good shape. TWH Earlier update: Made a quick update to raise PoPs (the potential for snow) over much of the western and central zones (including Billings). Radar was filling in aggressively and short range models were picking up on that. Also raised snow amounts to the north as snow was filling in quickly there too. TWH && .SHORT TERM...valid for Sun and Mon... Water vapor imagery this afternoon shows a potent wave traveling through northern Washington with flow aloft backing from northwesterly to westerly over southern Montana and northern Wyoming. This is promoting an onset of downsloping and gap flow winds along the mountains and generating some moderating temperatures. Lower spots along the rivers are stuck in the colder air but VWP in Billings shows southerly winds just above the first gate and a boundary is shifting northeast along a Lewistown to Hysham light producing brief snow showers. Wave over Washington sends a piece of energy that travels across northern Montana while more energy lingers back over the PacNW and helps develop a slower moving trough. This pattern sets up a period of active weather tonight...followed by a relatively lull late tonight into early Sunday...with another round of weather Sunday afternoon into Monday. Tonight a strong surface low expected to track across southern Montana but model solutions vary by about 80 miles in its track which is a huge difference between a couple of inches of snow and no snow. GFS is furthest south with the surface low which appears to be biases by trend to blend the surface inflection induced by the shortwave into a strong lee mountain wave signature on the east side of the Beartooth/Absaroka mountains. RAP NAM and SREF Models all track a low further north and maintain more downsloping for portions of south central Montana. Models do agree heaviest area of snowfall will be over and north of the Bull Mountains extending over towards the Crazy Mountains. Have lowered precipitation chances and amounts for the Billings area and locations like Hardin and Hysham but think that winter weather advisory in affect for areas north and west of Billings looks good. As the surface low moves into the region this will support a period of strong gap flow winds transitioning to a westerly mountain wave wind situation for the Livingston area and Beartooth Foothills. Have been watching to see if this will translate to a wave setting up along the Big Horn mountains but suspect that low level airmass will cool off enough early this evening to keep it from mixing down and impacting Sheridan. Do have strong winds at Burgess Junctions. Winds will let up as the surface low passes by. Cold front progged to cross the region between 9 pm and 2 am which will bring the best chance of snow for areas not in weather advisories but any snow with this front will be short lived. Exception will be over northern portions of southeast Montana where surface front may not pass as quickly supporting a bit longer snow. Advisory for this area still looks good but watching to see if the snow may not last that long depending on low track. Sunday morning sees a break in the snowfall but by afternoon backing flow aloft becomes More southwesterly and pushes moisture over the area while the arctic airmass deepens. This allows a light snowfall to develop mainly for Sunday night into Monday morning which is the greatest period of snowfall for areas like Billings. The upper flow is showing a bit stronger trough passing across Montana and moving a bit slower and this sets up better precipitation amounts for southeast Montana. Will have to watch that area for a possible advisory Monday. Other big story is the cold which will be nearly 40 degrees below normal for Monday. The high temperature is going to struggle to break zero. borsum .LONG TERM...valid for Tue...Wed...Thu...Fri...Sat... The GEFS showed uncertainty with the pattern beginning midweek, while the ECMWF ensembles showed high confidence with the pattern. That being said, the deterministic models were not in phase beginning on Wednesday, so used blended guidance for the PoPs. Generally, the extended period will be quiet with a warming trend. High amplitude trough from the short-term period will be over the region on Tuesday. 850 mb temperatures will be a few degrees higher than they will be on Monday, but highs will still be in the single digits. Lingering moisture will be over the SE zones and mountains for a slight chance of snow in these areas. Models still have troughiness over the area on Wednesday, but are out of phase with the energy in the trough. GFS showed a slight chance of snow over the SW mountains, otherwise the forecast will be dry. Temperatures will climb into the 20s in the W with teens E. Lee troughing Wed. night into Thursday will support possible Advisory winds in the gap flow areas. GFS showed a reinforcing trough for Thursday, while the ECMWF had brief upper ridging. Blends gave low PoPs N and W of KBIL, and highs in the 20s to low 30s. General troughiness continued on both models Friday through Saturday with chances for snow showers, mainly in the mountains, and highs in the 20s and 30s. Arthur && .AVIATION... Expect strong southwest winds with gusts to 50kts around KLVM will continue through around 09z. Around KSHR could see strong gusts to 45 kts briefly as a front moves through after 04z. Expect snow to continue overnight at all terminals with MVFR to IFR conditions expected. Heavier showers could produce localized LIFR conditions. Expect improving conditions at all terminal except KSHR after 12z. Reimer && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 012/013 906/002 918/009 906/021 008/031 011/031 014/033 77/S 74/S 21/B 11/U 11/B 11/B 11/B LVM 017/020 910/003 917/010 901/023 013/032 015/033 018/034 77/S 84/S 22/J 11/N 22/J 22/J 22/J HDN 013/014 902/005 921/010 909/021 004/028 007/029 010/031 66/S 74/S 22/J 11/U 11/B 11/B 11/B MLS 009/012 905/004 915/005 911/015 001/021 002/022 005/026 82/S 64/S 22/J 11/U 11/B 12/J 11/B 4BQ 016/018 903/005 916/007 911/018 002/027 006/028 009/030 64/S 76/S 32/J 11/U 11/B 11/B 11/B BHK 010/012 905/003 914/004 912/015 000/022 002/023 004/027 92/S 65/S 22/J 11/U 11/B 12/J 11/B SHR 020/025 906/005 919/008 914/020 000/028 007/030 010/033 56/S 76/S 32/J 11/U 11/B 11/B 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory in effect until 9 AM MST Sunday FOR ZONES 28>34-41-42-63. Wind Advisory in effect until 2 AM MST Sunday FOR ZONES 65-66. Winter Storm Warning in effect until 9 AM MST Sunday FOR ZONES 67-68. WY...None. && $$
Area Forecast Discussion
National Weather Service Columbia SC
1049 PM EST Sat Feb 17 2018 .SYNOPSIS... A frontal boundary will remain in the region through Sunday then lift north of the area as a warm front Sunday night into Monday morning. High pressure will be in control of the region Monday night into early Wednesday with the next front stalling just west of the area Wednesday afternoon and remaining nearly stationary through early Saturday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... All the diurnal showers have died out, so I have lowered pops through about 11 pm. After that time, the front will move through from the northwest. The large band of showers along the front is weakening with time, and low level water vapor loop indicates very little support for the maintenance of the line as it moves through overnight, so pops will be chance at best in the northern part of the CWA, while it looks like very little chance south of I-20 overnight. I have adjusted the POPs in the forecast accordingly. As for temps, there is a pretty significant gradient across the area early this evening, especially in the CSRA with lower 50s in McCormick County and lower 70s in Burke County at 8 PM. Therefore, I have had to adjust down the temps in the north, and raise the temps in the south for the next few hours. Eventually, the gradient should lessen as the cold front moves through overnight. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Sunday and Sunday night...Frontal boundary will be stalled over the southern CSRA early Sunday then begin moving back northward during the afternoon. The front will move through the central Midlands Sunday night reaching the NC and SC border by sunrise Monday. Although there will be increasing moisture once again with the front the bulk of the moisture will be over the northern CSRA and western Midlands into the Upstate. As such have tapered pops Sunday afternoon and night to keep chance pops along and north of I-20 with slight chance elsewhere. With limited dynamics do not expect much QPF with less than one tenth of an inch. Temperatures will be in the middle to upper 60s for afternoon highs with overnight lows in the lower to middle 50s. Monday and Monday night...Front will continue moving northward away from the region as high pressure builds in. This will keep southeasterly winds across the area with some cloudiness lingering...however with pwat values well below one inch do not expect any rain Monday or Monday night. With warm air advection Monday afternoon high temperatures will range from the upper 60s in the western Midlands and Pee Dee to the upper 70s in the southern CSRA. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Models are in good agreement through Saturday with some minor position differences late in the period. Upper level ridge will remain in place over the eastern US through the long term keeping above normal temperatures over the area next week. Surface and upper level highs will be offshore of the Carolinas Tuesday and remain nearly stationary through Saturday. This will keep southerly flow from the surface through the upper levels with Atlantic and Gulf moisture spreading over the region. Models indicate a weak upper level trough moving northward from the Gulf Tuesday night and Wednesday...however this feature is expected to remain just west of the forecast area. On Thursday a frontal boundary approaches from the west then stalls over the Upstate Early Thursday. With the surface high and upper level ridge over the area the front will remain west of the forecast area then push northward on Friday. The next cold front will try and move into the region late Saturday...however will again struggle to reach the area as the upper level ridge remains in place. With the moisture interacting with the frontal boundaries have remained with slight chance pops through much of the long term...mainly for the western Midlands through the Pee Dee. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Vad wind profile from KCAE radar indicating low-level wind shear at the CAE/CUB terminals. Guidance suggests lower shear at other terminals. Shear should diminish after 06z. Frontal boundary across the Piedmont SC early this evening. Broken cumulus /strato-cu across the area this afternoon...but thinning in the AGS/DNL terminal area. A few isolated showers but focus should remain mainly in the upstate where isentropic lift stronger. Front moves across the area overnight between 04z and 09z becoming stationary near the CSRA by morning. The latest HRRR suggests limited showers along boundary with mainly VFR ceilings overnight. Winds will shift to the north behind the front. High pressure will move in behind the front and trapped low- level moisture could result in ceiling and possible visibility restrictions Sunday morning mainly south and east of the CAE terminal and near the front across CSRA. MVFR ceiling restrictions expected near the front Sunday afternoon near AGS/DNL. EXTENDED AVIATION OUTLOOK...Chance of showers/restrictions at times Sunday night through Wednesday associated with onshore flow, isentropic lift, and then another approaching cold front. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
544 PM EST Sat Feb 17 2018 .AVIATION... The region of forcing supporting the area of moderate snow extending from metro Chicago across northern Indiana as of 22Z will weaken as it tracks across Se Mi late this evening. Thus the intensity of the snow is expected to diminish as it crosses the area in the 01Z to 05Z time frame. Nonetheless, some reduction in visibility to IFR in light snow is possible this evening. With temps holding in the low 30s, some minor (half inch or less) of slushy accumulation is possible). An MVFR stratus deck is already pushing into portions of Se Mi in advance of the region of light snow. Expect the lower clouds to continue to overspread the area this evening. While the forcing will rapidly push east after 05Z, model soundings with support of upstream observations indicate periodic low clouds will affect the region until late (after 14Z) Sun morning with a push of warmer/drier air from the south arrives. For DTW...The heaviest snow is expected to fall well south of metro this evening. Nonetheless, light snow will impact the terminal in the 02Z to 05Z time frame. Any accums will less than a half inch with sfc temps holding in the 30s. /DTW THRESHOLD PROBABILITIES... * High in ceilings below 5000 ft tonight. Moderate Sunday morning. * High for ptype as snow this evening. && .PREV DISCUSSION... Issued at 315 PM EST Sat Feb 17 2018 DISCUSSION... Despite the thick canopy of high clouds around today, temperatures were still able to rise into the low/mid 30s. Strong upper wave tracking along/close to the southern Michigan border late today. Bulk of isentropic assent/moisture advection looks to be used up just to saturate the low/mid levels, and thus if measurable snow is able to develop this evening, looking at half inch or less. Narrow axis of 850-700 MB specific humidity in the 1.5-2 g/kg range sliding through during evening, but already quickly drying out after midnight, lowering to around 0.25 g/kg by 12z Sunday. Mins dependent on low clouds scattering out or clearing, but latest RAP indicating higher moisture/rh at 925 MB holding on through majority of the night, and will thus hold temps in the 20s. Pronounced upper level ridging/height rises to take place over the Great Lakes Region during Sunday, with strong low level southwest flow to lead to significant warming, as 850 mb temps rise to around zero toward sunset and into the mid single numbers Sunday night. Airmass will be very dry, as 850 mb dew pt depressions increase to between 40 to 50 C Sunday evening. However, this will dramatically change for early next week, as big convergence of Pacific/Gulf of Mexico surges north and reaches southeast Michigan with PW Values around 1.25 inches, which looks to be record territory for February. Strong model consensus amongst Euro Ensemble members indicating highs in the 60 to 65 degree range on Tuesday across the majority of southeast Michigan, placing record highs in jeopardy. One wave of low pressure tracking through on Monday will bring rain showers, with active frontal zone then lingering over the area, with cold front looking to slide through Tuesday night or Wednesday morning. Marginal instability (showalter index falling to around zero) leads to mention of thunder, but only acting to enhance rainfall, as surface/near surface will be stable enough to preclude severe concerns. One to two inches of rain is likely in the moisture rich environment Monday through Wednesday morning, with 3 inches certainly possible. Positive tilted upper level trough axis lingering across the Rockies Wednesday-Thursday will lead to just a modest shot of cold air (for February standards) following the cold front, as high pressure (1040+ MB) slowly slides through the northern Great Lakes on Thursday. Retreating high Thursday night-Friday, but surface ridge axis potentially holding on long enough during Friday to get through the day dry before a warm front lifts north. MARINE... Winds will remain out of the southwest with gusts topping out around 30 knots through this evening ahead of an advancing cold front. Expect the higher winds gusts to be tempered a bit due to extensive ice cover. Winds will veer to a more west-northwest direction in the wake of the front overnight, but will not last long as southerly flow kicks back in Sunday afternoon as a warm front lifts northward through the Great Lakes. Winds gusts will again remain around 30 knots Sunday evening as the front lifts through the region. HYDROLOGY... A strong warm and moist advection regime will kick into gear Monday through Wednesday ahead of a slow moving front. This warming and wet trend will result in a full melt off of present snow cover across southeast Michigan. Several periods of rainfall can be expected during this time with widespread rainfall totals of 1-2" over the course of Monday to Wednesday. There is still some uncertainty with where the higher rainfall amounts will fall, but there is potential for some locations to near 3 inches of rainfall where stronger pockets of convection occur. While the melting snow will unlikely be enough to support flooding, the potential for rainfall in combination with the snow melt could cause some rises in area rivers and streams. Ice breakup on area rivers and streams caused by warmer temperatures will also be something to keep an eye on, which could exacerbate any local flooding issues. CLIMATE... Record high temperatures will be possible across much of southeast Michigan Tuesday. Here is a look at record high temperatures for Tuesday, February 20th: Detroit 63 (2016) Flint 61 (1930) Saginaw 62 (1930) With the high moisture content, good chance to break the high minimum records for February 20th as well: Detroit 47 (1930) Flint 45 (1930) Saginaw 46 (1930) && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....SC DISCUSSION...SF MARINE.......AA HYDROLOGY....AA CLIMATE......SF You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Houston/Galveston TX
900 PM CST Sat Feb 17 2018 .UPDATE... The main update with the forecast tonight is to account for a farther south progression of a cold front than previously advertised. The KHGX radar shows this boundary stretching from Vanderbilt to Bonney to Texas City and with the KHGX VAD wind profiler showing very light winds above the surface doing little to inhibit the southward movement, expect density differences to drive this boundary off the coast within the next 2-3 hours. As this front cleared the NWS Houston office, the temperature dropped 7 degrees within 30 minutes. Given these short-term trends, have lowered low temperatures a few degrees into the upper 40s to near 60. A brief northerly wind shift associated with this boundary moving off the coast may result in a brief respite in sea fog (detailed in the marine section below) before winds veer to the east sometime in the 3-6 AM timeframe. SPC mesoanalysis shows the 925 MB front located farther north, roughly north of Interstate 10, and convergence along this feature may produce isolated to scattered showers through the overnight hours north of a Columbus to Liberty line. Patchy radiation fog may also be possible as dew point depressions decrease overnight through mid morning, with best chances west of a Madisonville to Katy to San Luis Pass line. Huffman && .MARINE... A weak boundary continues to move toward the coast. Models are not in great agreement but the latest HRRR shows the boundary making it into the coastal waters before becoming diffuse later tonight. North winds will develop in the wake of the front and slightly drier air will likely make it into the waters. The drier air will help erode the fog and the north winds should push any remaining fog away from the coast. There should be some brief improvement in visibility between 04-08z. East winds will develop after midnight and become SE on Sunday. Fog is expected to redevelop between 08-10z and persist intermittently through Sunday morning. Onshore winds will strengthen Sunday afternoon as low pressure over eastern Wyoming deepens. The low will push east on Monday/Tuesday and drag a cold front into the state. The front will probably stall and onshore winds will persist into Wednesday. Periods of sea fog will likely hang around during the first half of next as warm and moist air continues to flow over the cooler shelf waters. The long S-SE fetch will bring slightly warmer water toward the Upper Texas Coast and this may mitigate the threat for dense sea fog early next week. 43 && .PREV DISCUSSION... /ISSUED 556 PM CST Sat Feb 17 2018/ AVIATION... A weak front extended from about Liberty to downtown Houston and then along the I-69 corridor to about Edna. Showers were beginning to develop along this feature. Short term guidance shows the boundary remaining nearly stationary and gradually becoming diffuse. Low ceilings expected to develop areawide as deep mstr builds beneath a capping inversion. LIFR/IFR cigs expected late tonight into Sunday morning with a gradual improvement to MVFR by afternoon. Sea fog will be an issue along the coast and visibility will fall below a mile at times at KGLS and probably KLBX. 43 $$ && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 52 71 64 79 66 / 30 20 20 20 20 Houston (IAH) 57 74 65 78 67 / 30 20 20 20 10 Galveston (GLS) 60 71 64 73 66 / 20 20 20 20 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...Dense Fog Advisory until noon CST Sunday for the following zones: Coastal waters from Freeport to the Matagorda Ship Channel out 20 NM...Coastal waters from High Island to Freeport out 20 NM...Galveston Bay...Matagorda Bay. && $$ Discussion...14 Aviation/Marine...43
Area Forecast Discussion
National Weather Service Jacksonville FL
854 PM EST Sat Feb 17 2018 .UPDATE...A Gulf Coast dense sea fog bank along the west coast of Florida has moved north and northeast with light southwesterly flow. This fog is just upstream of the Suwannee Valley and just has started to encroach the western part of Suwannee County this mid evening which is evident on the GOES-16 Night-time Microphysics contrasts. Hence has put out a Dense Fog Advisory for Columbia, Gilchrist, Hamilton, and Suwannee Counties this mid evening through 10 am. Then the fog will continue to advect during the post mid-night hours into Clinch, Ware and Echols Counties. As the nocturnal hours progress into the pre-dawn hours fog is expected to overspread most areas toward the coast and then nearshore waters. Will watch the progression of the fog advection, for potential additional advisories downstream, east of 301. The HRRR hourly model runs continue to show this trend. A low chance of showers across SE GA for Sunday with mostly cloudy to partly cloudy skies across NE FL once morning fog and low stratus begin to lift and break apart. The cold front will shift west more as a backdoor cold front with NE flow pressing down the local Atlantic coast through Sunday afternoon as high pressure builds NE of the region. && .AVIATION... Mainly prevailing VFR under light SSW flow 5-8 kts for area terminals this evening. Low stratus and fog are starting to encroach the Suwannee Valley. As the night-time hours progress low stratus and fog will cotinue to further advect inland from the Gulf Coast region bringing restrictions from GNV to VQQ first between 05-08Z where there is elevated confidence of LIFR and VLIFR conditions. Restrictions of IFR expected to impact the coastal terminals after 09Z through 14-15Z Sunday. Winds will transition to NE through Sunday, impacting SSI first by late morning, then the wind shift progressing down the coast into the afternoon which could bring sea fog lingering over the Atlantic inland during Sun evening potentially impacting SGJ. && .MARINE...WSW winds this evening ahead of the approaching cold front. Fog advection from the Gulf will affect the nearshore waters during the pre-dawn hours into the early morning daylight hours. There might be a temporary abatement of the fog over the near-shore between 10 am and 1 pm. This fog will likely re- settle in over the nearshore waters during the afternoon hours over the adjacent waters as onshore flow develops. The cold front will slowly settle across the local waters Sunday as high pressure builds northeast of the region. Onshore flow persists through this upcoming week as high pressure dominates northeast of region. Headlines are not expected this forecast period. Rip Currents: Low risk Sunday. && .PRELIMINARY POINT TEMPS/POPS... AMG 61 76 59 82 / 10 20 10 10 SSI 60 71 58 73 / 0 20 10 10 JAX 59 77 58 80 / 0 10 10 10 SGJ 60 74 60 77 / 0 10 10 10 GNV 58 80 58 83 / 0 10 10 0 OCF 58 81 60 84 / 10 10 10 0 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Dense Fog Advisory from 2 AM to 10 AM EST Sunday for Alachua- Baker-Bradford-Union. Dense Fog Advisory until 10 AM EST Sunday for Columbia-Gilchrist- Hamilton-Suwannee. GA...Dense Fog Advisory from 2 AM to 10 AM EST Sunday for Clinch- Echols-Ware. AM...None. && $$ Cordero/Shashy/Peterson
Area Forecast Discussion
National Weather Service Melbourne FL
844 PM EST Sat Feb 17 2018 .DISCUSSION... Main forecast concern tonight will continue to be fog development late in the overnight hours through early morning Sunday. MOS guidance continues to show best potential for dense fog/stratus moving into Lake County, and eastward through the I-4 corridor and toward the Volusia coast. Earlier runs of the local WRF and HRRR also agreed quite well on this scenario. However, the most recent runs of both models have now backed off on fog development quite significantly, keeping any areas of dense fog west and north of Lake and Volusia counties. With favorable setup of light winds and mostly clear skies in place, will keep areas of fog mentioned in the forecast for northern areas, with patchy fog farther south. However, the recent trends in the models do leave room for a little more uncertainty in amount of fog coverage for late tonight. Regardless, localized visibilities of a quarter of a mile or less will at least be possible. Favorable radiational cooling conditions should again allow temperatures to fall into the upper 50s to low 60s over much of the area overnight. && .AVIATION...VFR conditions expected to persist through 06z, then fog/stratus development overnight will reduce cig/vis as low as IFR/LIFR through early Sunday morning. Best potential for these conditions will be across northern TAF sites, with more tempo reductions to IFR/MVFR from patchy ground fog from KMLB-KSUA. Fog and stratus will burn off into the morning, with VFR conditions then expected to prevail through the afternoon. && .MARINE...There is a potential for dense fog to push off the Volusia county coast again early Sun morning. Otherwise, boating conditions will remain favorable tonight through tomorrow with winds 10 knots or less and seas 2-3 feet. A slight increase in onshore flow to 10-12 knots is indicated Sun afternoon. && .PRELIMINARY POINT TEMPS/POPS... DAB 59 78 62 81 / 0 0 0 0 MCO 59 84 62 84 / 0 0 10 0 MLB 61 81 65 81 / 0 10 10 0 VRB 59 82 65 81 / 0 10 10 0 LEE 62 83 63 84 / 0 0 0 0 SFB 60 82 62 84 / 0 0 0 0 ORL 62 83 64 84 / 0 0 0 0 FPR 58 82 64 81 / 10 10 10 0 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Weitlich/Smith
Area Forecast Discussion
National Weather Service Marquette MI
439 PM EST Sat Feb 17 2018 .SHORT TERM...(This evening through Sunday) Issued at 410 PM EST SAT FEB 17 2018 WV imagery and RAP analysis indicated cyclonic wrly flow through the n cntrl CONUS around a deep mid/upper level low west of Hudson Bay. A shortwave trough over WI supported an area of light snow that has from far srn Upper MI through ern WI into nrn IL. Drier low level air further north has limited coverage of the pcpn into the rest of the cwa. Another signficant upstream shortwave was moving through the Pacific Northwest. Tonight, any remaining snow over the far s or se cwa will move out during the rest of the afternoon, per radar/satellite trends. Otherwise, favorable radiational cooling conditions overnight should allow temps to drop into the single digits over inland locations before mid/high clouds increase from west to east late. Sunday, a broad area of WAA and isentropic lift will strengthen as the shortwave move through the nrn plains. Models suggest that the heaviest band of snow will move through nrn MN into wrn Lake Superior and mainly the Keweenaw Peninsula. There is still some uncertainty with the snowfall amounts as the ECWMF/NAM and regional GEM remained or trended farther north compared to the GFS with higher QPF axis. So, an advisory was issued only for the Keweenaw where the highest amounts are likely. With 2-3g/Kg moisture avbl and a period of intense lift and mid level fgen, local amounts in the 3 to 6 inch range will be possible. Farther south amounts should range from 1 to 3 inches over most of the rest of the nrn half of Upper Michigan. .LONG TERM...(Sunday night through Saturday) Issued at 438 PM EST SAT FEB 17 2018 Active period of winter weather still expected into Tuesday. Ptype may be more of an issue for more areas, especially Mon night into Tue. Summary on expected weather and possible headlines Mon into Tue: Headlines will likely be needed over all of Upper Michigan at some point. A winter storm warning for just warning criteria snowfall seems unlikely, however with models trending toward more mixed precipitation and ice, could see warning at some point due to moderate wet snow amounts and/or significant ice accums, especially south and east. Would imagine most headlines for this event will come out later tonight or on the dayshift on Sunday. Lead system that brings snow over mainly northwest Upper Michigan exits after midnight over eastern forecast area. Could see brief uptick in the snow east of Marquette toward eastern U.P. with increasing moisture advection and continued lift in right entrance region of jet over northern Ontario and Quebec. Could see some light freezing drizzle as the light snow tapers off and before next round of light snow begins to move in over western U.P. late. Mon into Mon night system still looks complicated to project mainly due to two jet streams (polar and sub-tropical) that will be coming together to bring the system into the Upper Great Lakes. Most of the precip initially upstream of Upper Great Lakes on Mon morning will be along sub-tropical jet in form of rain/freezing rain across mid Mississippi River Valley while the main area of snow will be expanding from the northern Plains to south half of MN and into north half of WI on front side of larger troughing aloft and in H85- H7 gen area in right entrance of polar jet from northern Plains to Quebec. Though main sfc low and even sfc trough stays well to the south of Upper Michigan (only as far north as southern WI into lower Michigan) Mon into Mon night, fgen forced snow enhanced by divergence aloft from upper jet and convergence along H85 trough axis from near Omaha to south central Upper Michigan should expand across Upper Michigan through the day. Potential for heavy snow looks on the lower side as strongest moisture advection stays south and east of Upper Michigan closer to the sfc low/trough and there is not a stronger shortwave trough/deformation area that lifts across the area. At this point, seems best shot at seeing warning snowfall amounts will be over western Upper Michigan where there is less chance of any mixed precip throughout and where SLRs may end up a bit higher. WPC probabilistic winter guidance shows highest probabilities for seeing at least high end advy for those areas as well. Another wrinkle that is starting to show up is that most models now show lack of ice nucleation occurring outside of when main area of snow moves through late Mon morning into Mon afternoon. If that is true, there would be more freezing drizzle or light freezing rain over at least the south and east late Mon aftn through Mon night. Some guiance would have freezing precip even as far west as Iron to Baraga county on Mon night. That is a change from recent model runs. Next low pressure wave lifts along the existing sfc boundary late Mon night into Tue. Possible that our far southeast zones may see 0.10 to 0.20 inch of qpf from this next segment of this drawn out system. Soundings indicate lack of ice aloft though and even if there is deeper moisture, a farther north warm layer aloft is now showing up. ECMWF increases H85 temps to around +5c over eastern forecast area on Tue. While that warm layer aloft is present, sfc temps are in the 20s. Freezing rain looks likely or maybe sleet if warm layer is more 1-3c. Even more significant icing may occur farther south into WI deeper into the heavier qpf from this next wave. But, we are looking at more freezing rain and icing issues even into our area. Widespread wintry precip should exit eastern area Tue night with just some light lake effect possible into Wed as cooler air moves across. High pressure will bring drier weather late this week before another system brings mainly light snow to the area by next weekend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 115 PM EST SAT FEB 17 2018 MVFR cigs at KCMX adied by some lake moisture in wsw flow are expected to give way to VFR conditions by mid afternoon as drier air moves in. VFR conditions should then prevail at at all sites into Sunday morning. Light snow will move into the west at KIWD/KCMX by late Sun morning with MVFR and possibly IFR vsby by the end of the period. Cigs should remain MVFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 410 PM EST SAT FEB 17 2018 A few southwest gale force gusts to 35 knots are expected Sunday night over eastern Lake Superior. Otherwise, winds are expected to stay below gales through the rest of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory from 9 AM Sunday to 1 AM EST Monday for MIZ001-003. Lake Superior... None. Lake Michigan... Gale Warning from 4 PM Sunday to 1 AM EST Monday for LMZ248-250. && $$ SHORT TERM...JLB LONG TERM...JLA AVIATION...JLB MARINE...JLB
Area Forecast Discussion
National Weather Service Nashville TN
849 PM CST Sat Feb 17 2018 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Rain is well clear of the Cumberland Plateau and the rest of the night will be dry for the entire area. Looking at the Nighttime Microphysics RGB, clearing line is just north of the area. HRRR shows more clearing than the previous forecast. Sky grids were lowered to reflect this trend. Hourly temperatures are warmer than forecasted at this point and were adjusted. Still think we`ll get to forecasted lows given the trend of less cloud cover. Dew point depressions should fall as we get toward dawn allowing for some patchy fog development. && .AVIATION... 00Z TAF DISCUSSION. Cigs ranging from MVFR to LIFR at airports this evening will clear out overnight with SKC returning. However, this will lead to fog formation with MVFR/IFR vis and possibly lower towards sunrise. Light west winds this evening will become northerly overnight then east/southeast on Sunday. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Reagan AVIATION........Shamburger
Area Forecast Discussion
National Weather Service Pueblo CO
845 PM MST Sat Feb 17 2018 .UPDATE... Issued at 840 PM MST Sat Feb 17 2018 Winds a little slow to increase this evening, though high mountain pass obs were finally beginning to trend upward at 03z. Latest few runs of the HRRR suggest strongest winds may not occur until after sunrise on Sun, with a peak in mid to late morning. Won`t change any highlights at this point, though may need to decrease wind speeds somewhat overnight in the next update if downslope flow continues to be slow to develop. && .SHORT TERM...(This evening through Sunday) Issued at 353 PM MST Sat Feb 17 2018 ...High Winds to return for the southeast mountains and adjacent eastern slopes mainly west of I-25... ...Critical Fire Weather Conditions expected for the southeast plains and lower slopes of the southeast mountains on Sunday... Challenge in short term is how far down the slopes high winds will progress again overnight. With upper low digging southward into the Pacific NW tonight, flow aloft shifts to a more west southwesterly component. This is a more favorable cross barrier flow for much of the southeastern mountains. However various high res models have differing solutions on the development of a mountain wave and how far down the slopes it progresses. The local 4 km WRF and 3km NAM Nest suggests strong downslope winds will spread from the higher peaks into portions of the I-25 corridor from late tonight through Sunday morning...while HRRR is more conservative and keeps winds confined to the higher peaks. Model cross-sections look best across northern areas (El Paso county) with a good amount of reverse shear developing towards morning though there isn`t much of a mountain top inversion. However there doesn`t necessarily have to be as we saw last night and models are not good at handling these details anyway. Leaning on various high res models have upgraded the high wind watch to a warning, though wasn`t getting enough coverage in the west central portions of Las Animas county to warrant an upgrade there. In the El Paso county area...think focus will shift to the southwest side of Colorado Springs and Fort Carson area towards dawn given the more southwesterly component aloft. Another area to watch will be the I-25 corridor south of Colorado City. The west side of Custer county into the wet mountain valley could also see a period of damaging winds overnight according to WRF and NamNest. Will keep overnight lows on the warm side to account for downslope winds which are likely to continue overnight to at least some degree along/west of I-25. For Sunday looks like mountain wave parameters should break down by late morning...though winds will remain strong as upper jet translates in aloft. Should start to see moisture increase along the Continental Divide during the afternoon with snow developing during the late afternoon. Main brunt of the accumulations holds off until later Sunday night. Meanwhile...gusty winds will spread into the plains during the afternoon. Temperatures across the plains will warm into the 70s...well above normal for this time of year, and combined with dry surface dew points will lead to widespread critical fire weather conditions. Have upgraded the Fire Weather Watches to Red Flag Warnings. Have added zone 225 to account for the lower eastern slopes along the I-25 interface as winds will be particularly strong in this area. -KT .LONG TERM...(Sunday night through Saturday) Issued at 353 PM MST Sat Feb 17 2018 ...Windy with Snow and Blowing Snow across the ContDvd Monday... Sunday night-Tuesday...Current models continue to dig the Pac Northwest system into the Great Basin and lift it out across Rockies in the late Sunday night through Tuesday timeframe, with only slight differences in timing. The ECMWF still is a tad slower with this system, which allows for shallow cool airmass to filter across the Eastern Plains through the day Monday, where as the GFS and the NAM solutions keep the cooler air north of the the area with strong west to southwest flow in place across the Southeast Plains. All solutions point to increasing snow along and west of the ContDvd Sunday night, with snow likely across the ContDvd Monday and Monday night. With strong orographic southwest winds of 25 to 50 mph, have upgraded winter storm watch for the Eastern San Juan Mountains to a warning from 06z Monday through 12z Tuesday. Snow amount of 8 to 14 inches are expected, with localized amounts up to 20 inches possible on favored southwest peaks. We have also issued winter weather advisories for lower Rio Grande Valley (3 to 6 inches) and for the Sawatch and Mosquito Ranges (4 to 8 inches, locally up to a foot) for the same timeframe. Strong and gusty southwest winds through the day Monday becomes more westerly Monday night and Tuesday, with difficult travel expected across the higher mountain passes in snow and blowing snow. Further east, the increasing southwest flow aloft will again lead to potential for strong downslope winds across the Southern Mountains and lower eastern slopes Sunday night into early Monday morning, with model cross-sections indicating a mean critical layer mainly across the Southern Sangre de Cristo Mountains. Current grids indicating gusts in the 60 to 70 mph range across this area, and later shifts may need to go with wind hightlights. Monday temperatures and winds across the plains are tricky at this time, with another big bust potential with a shallow cold airmass moving across the Plains. As mentioned earlier, the faster GFS and NAM have an induced surface low across the Southeast Plains Monday, keeping strong and gusty west to southwest winds across the I-25 corridor and gusty southerly winds across the far Eastern Plains, where as the slower EC solution has a weaker low near TAD Monday morning, which allows for shallow cold airmass to filter across the Plains through the day. Have tried to blend towards this cooler solution, with temps in the 40s and 50s along and north of the Highway 50 Corridor Monday morning, with temps then cooling into the afternoon. If the GFS and NAM solutions are more correct, there will be possible critical fire weather conditions across most of the plains on Monday, with current grids indicating possible fire weather highlights for Las Animas County and possibly southern portions of Baca County. By Monday night, snow spreads across the high mountain valley and into the Eastern Mountains, with generally light accumulations expected. Shallow cold airmass spreads across all of the southeast plains with stratus banked up across the lower eastern slopes, leading to chances of light snow across the I-25 Corridor and the eastern plains through the day Tuesday, with the overrunning pattern. Cool upslope flow across the plains on Tuesday will keep highs in the 20s and 30s areawide. Wednesday-Saturday...Continued west to southwest flow aloft will lead to a slow warming trend across the area through the end of the work week. Dry conditions look to return to Eastern Colorado, with light snow possible across the ContDvd through the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 353 PM MST Sat Feb 17 2018 Synopsis: Mountain wave activity brings gusty and variable wind conditions and low level wind shear to the forecast points. See discussion below for details. KALS: VFR conditions are expected throughout the forecast period. Expect gusty winds during the daytime hours. KCOS: High resolution models are resolving a mountain rotor forming over KCOS during the overnight hours. During this time period, expect low level wind shear. Gusty winds are expected during the afternoon hours tomorrow. VFR conditions are expected throughout the forecast period. KPUB: Pueblo should be far enough west from any mountain rotor activities, but expect strong winds for the majority tomorrow, gusting in the afternoon hours. VFR conditions are expected throughout the forecast period. && .PUB WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 10 AM to 6 PM MST Sunday for COZ222- 225>237. High Wind Warning until noon MST Sunday for COZ072>075-078>082- 084-085-087. Winter Weather Advisory from 11 PM Sunday to 5 AM MST Tuesday for COZ058-060-061-065>067. Winter Storm Warning from 11 PM Sunday to 5 AM MST Tuesday for COZ068. && $$ UPDATE...EP SHORT TERM...KT LONG TERM...MW AVIATION...KTS
Area Forecast Discussion
National Weather Service Charleston WV
1012 PM EST Sat Feb 17 2018 .SYNOPSIS... Low pressure system exits overnight. High pressure crosses Sunday. Warm front Monday, and then a cold front midweek. && .NEAR TERM /THROUGH SUNDAY/... As of 1010 PM Saturday... Cancelled winter weather advisory for snow for the higher terrain of Nicholas County, and the lower terrain of Pocahontas County. Left it in effect until its 09Z expiration time for the higher terrain of Randolph, Pocahontas and Webster counties for upslope snow accumulations there of up to two inches. As of 805 PM Saturday... With last small batch of precipitation with vort max exiting, and having not amounted to much after all, the WSW for snow has been cancelled for the remainder of the lowlands, and the higher terrain of the central WV mountains. The WSw continues for the northern mountains, mainly the higher terrain therein. As of 735 PM Saturday... Flood watch cancelled as no new flood warnings are anticipated, and western portions of the lowland winter weather advisories for snow are cancelled with the exodus of the snow, and temperatures rising back above freezing for the time being. The PoPs have been adjusted to reflect the faster exodus of the precipitation, and temperatures again fine tuned as they recover slightly with the precipitation exodus. A much nicer day is on the way Sunday, as high pressure crosses. As of 355 PM Saturday... Adjusted surface temperatures per current trends via the Hires arw and nmm, and NAMnest. Now have snow totals of 2 to 4 inches in the middle Ohio Valley, northern WV and higher elevations of the central mountains, and 4 to 6 and locally higher in the northern mountains. Used 12:1 snow ratios from WPC given reports of large flakes suggestive of good dendritic growth. WSW for snow expanded eastward and southward. As of 320 PM Saturday... A developing sfc low pressure system will cross the area from southwest to northeast through this evening. This system will bring short periods of heavy snow across southeast OH, and northern WV through this evening. There is a Winter Weather advisory for these areas through 2 AM. South to southwest flow is causing a warm wedge west of the mountains where most pcpn is falling as liquid. Colder temperatures across southeast OH and the higher elevations of WV will see a mix bag of pcpn or all snow. A period of FZRA will be possible along the eastern slopes of WV due to cold air damming east of the mountains. Therefore, another Winter Weather advisory is in effect for FZRA and mix pcpn through 4 AM. A flood watch continues in effect for the southern coal fields, including Putnam and Kanawha counties of WV and extreme southwest VA through 4 AM Sunday. Used consensus of models with some weight of the HRRR model for temperatures through the period. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 250 PM Saturday... The warm front will push north across the area on Monday. Any precip amounts will be fairly light, so not expecting more issues with flooding from this wave. We will be well within the warm sector on Tuesday and temps will be climbing into the 80s...yes the 80s. Forecast temps are in the record high range for climate sites -- and could be flirting with record highs for the month of February as a whole. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 255 PM Saturday... By mid week we will have a cold front pushing into the Ohio Valley from the west. Timing differences continue between the model guidance, but starting to look more like a late Wednesday afternoon or night passage. Have introduced thunderstorm possibility as well for this period as forecast soundings are indicating marginal instability. The front gets hung up and stalls and this could make for the possibility for more heavy rainfall through the end of the week. Still too early to tell at this time, but based on current antecedent conditions, flooding is looking like it may be a problem again. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... As of 735 PM Saturday... MVFR to even VFR conditions begin the period east of the Ohio River, until the wind shifts to the west tonight as low pressure exits. Mainly IFR conditions begin the period along the Ohio River. IFR conditions, mainly on ceilings, will spread east overnight with the wind shift to the west. Expect spotty light rain and drizzle in the lowlands, with snow and sleet also possible in the mountains. Not much fog is anticipated as the precipitation exits overnight, and ceilings will gradually come back up, with MVFR or better predominant ceilings toward dawn Monday, perhaps a bit beyond dawn in the northern mountains. MVFR morning cu ceilings will lift and break up by late morning, and high pressure will provide a VFR Sunday afternoon. Southerly surface flow east of the Ohio River will shift to west throughout the area by 0-3Z, and become a bit gusty in the mountains overnight. Surface flow will diminish to light west Sunday morning, and then back to light south Sunday afternoon. Moderate southwest flow aloft tonight will become moderate west overnight, moderate northwest by dawn Sunday, light north after daybreak Sunday morning, and then light south Sunday afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z MONDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: Timing of improving conditions may vary overnight, though more confident in MVFR morning cu Sunday morning. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SUN 02/18/18 UTC 1HRLY 03 04 05 06 07 08 09 10 11 12 13 14 EST 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY M M H H H H H H H H H M HTS CONSISTENCY M M M M H H H H H H H L BKW CONSISTENCY H H M H M H L H H H H L EKN CONSISTENCY L L L L M M L L L M H M PKB CONSISTENCY L M M L H H H H H H H L CKB CONSISTENCY L L L M M M H H H H H M AFTER 00Z MONDAY... IFR possible in showers late Wednesday or Wednesday night into Thursday. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Winter Weather Advisory until 4 AM EST Sunday for WVZ522-523- 526. OH...None. KY...None. VA...None. && $$ SYNOPSIS...KMC/TRM/MZ NEAR TERM...ARJ/TRM SHORT TERM...MPK/AB LONG TERM...MPK/AB AVIATION...TRM
Area Forecast Discussion
National Weather Service Tulsa OK
934 PM CST Sat Feb 17 2018 .DISCUSSION... Latest surface analysis indicates high pressure centered over Arkanas this evening with light and variable wind across much of our forecast area. Deepening trough through the Plains will result in veering low level wind overnight then strong southerly wind Sunday. Valley fog has already resulted in variable visibilities across portions of wrn AR this evening, which will likely continue overnight. Low clouds should develop into sern Oklahoma late tonight, and then across portions of central/nern OK Sunday. Rain chances still look to return late Sunday/Sunday night with widespread activity Monday-Tuesday. Ongoing forecast is trending well this evening and no changes needed at this time. && .PREV DISCUSSION... /Issued 534 PM CST Sat Feb 17 2018/ DISCUSSION... The discussion for the 00Z TAF forecast can be found below. AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. The latest HRRR is hinting at the potential for some valley fog at FSM tonight. Since FYV is prone to valley fog as well, especially after the recent rain event, have inserted tempo groups at both sites for IFR fog around midnight into the early morning hours. Increasing high cloud overcast and south to southeast winds should lead to its demise Sunday morning. The HRRR also suggests that the initial northwestward surge of low clouds/moisture will miss our area to our west initially on Sunday. Given some uncertainty, few to sct low cloud groups were maintained in the E OK TAFs. VFR conditions will prevail for the most part on Sunday, with potential for low end VFR cigs by the end of the day. Strong, gusty S winds will also prevail on Sunday. Lacy PREV DISCUSSION... /Issued 413 PM CST Sat Feb 17 2018/ DISCUSSION... A rather unsettled weather pattern will prevail over the next week, with several rounds of much needed rainfall expected. Despite the overnight rainfall, fire danger will be a concern Sunday as gusty southerly winds develop, and temperatures warm into the 60s. Low level moisture will rapidly return north Sunday afternoon and evening, and scattered elevated convection may develop overnight Sunday night and persist into Monday evening. The most widespread and heaviest rainfall is expected late Monday night and Tuesday as a strong cold front drops south across the area. A few strong to marginally severe storms will be possible, but locally heavy rainfall looks to be the main concern. Some drier air will work into parts of northeast Oklahoma Tuesday night, but an upper level disturbance will spread light precipitation back over the area during the day Wednesday. Surface temperatures will likely remain below freezing across the northern part of the forecast area, so the precipitation will fall as light freezing rain in that area. A warming trend will develop Thursday and last into the weekend, but unsettled weather will continue, with rain chances returning Thursday night into the weekend. Stayed close to guidance temperatures the next couple days. && .PRELIMINARY POINT TEMPS/POPS... TUL 35 63 57 71 / 0 0 40 50 FSM 34 62 54 71 / 0 0 40 50 MLC 36 63 58 70 / 0 10 40 50 BVO 29 64 55 73 / 0 0 40 50 FYV 28 59 53 67 / 0 0 40 50 BYV 31 60 52 68 / 0 0 40 50 MKO 35 63 56 70 / 0 0 40 50 MIO 32 62 54 69 / 0 0 40 50 F10 36 63 57 70 / 0 0 40 50 HHW 38 62 56 72 / 0 10 40 50 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...69 LONG TERM....05 AVIATION....30