Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/07/17

Area Forecast Discussion
National Weather Service State College PA
1102 PM EST Fri Jan 6 2017 .SYNOPSIS... A cold weather pattern with below normal temperatures and lake effect snow will stay locked in through the weekend before moderating next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Not a lot happening as of 9 pm, with the lake effect hugging the lake shores and staying below the radar up over NRN Warren county. Main tweak was to nudge up the POPs a bit given the latest HRRR trends in pushing an area of light snow over my far SERN zones later tonight and Saturday morning. From earlier: Thicker clouds are moving back toward the SRN part of the area as a surface wave forms over the SERN states and moves toward Cape Hatteras. While high pressure begins to build in from the west overnight, the surface wave moving off the SE US coast will spread clouds and precip up along the Mid Atlantic coast later tonight into Saturday. The biggest concern is if the far SERN zones get clipped with a bit of light snow toward sunrise Saturday into Saturday morning. Most of the remainder of the area will be clear to partly cloudy tonight setting the stage for some decent radiational cooling. Lows will drop to near zero over the colder spots of the north to the mid teens over the southeast. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... An upper trough over the lower Great Lakes/Ohio will keep the mention of lake effect snow showers in the far NW mountains, but with accums generally an inch or less. Any light snow that might creep into York or Lancaster counties late tonight will move east of the area by mid morning with improving skies thereafter. Highs will range from the mid teens to mid 20s from NW to SE. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Surface low is well off the east coast with high pressure centered over Iowa. NW flow continues with cold air advection.The cold bottoms out on Sunday with passage of -20C air at 850mb. Max temps are projected to average 10 to 20 degrees below normal for early January. Gusty winds should drop wind chills below zero across the Alleghenies and into the single digits over the Lower Susq Valley. A Short-wave moves southeast across the Eastern Great Lakes Saturday night bringing some snow to the northern zones and then the lake effect fetch becoming more favorable into Sunday - bringing an enhanced period for potential lake effect snows over the NW. During the day on Sunday, we could also see these bands snake into the central mountains and a quick accumulation is poss. Center of the high passes to the south on Monday with return flow kicking in and expected to moderate temperatures through early next week. High clouds over western PA with warm air advection. The next shot of precip will arrive on Tuesday with high prob of ptype issues as strong SW flow directs warm air into retreating cold dome. Without getting too detailed, latest runs still showing colder air trapped for much of Tue into Tue night, so continued to mention a wintry mix. By Wed, precip should change to all rain ahead and along a cold front with a soggy day in store. Models now trending a little milder for the end of the week. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR tonight with mid-high clouds increasing over the southern airspace. MVFR cigs now likely to hold off until Saturday afternoon across the wrn 1/3 of the airspace as NW flow increases on backside of low pressure tracking off the Mid Atlantic coast. Latest HI RES models suggest a slight uptick in snow chances and potential for MVFR/IFR vis at LNS and will continue with PROB30. Expect winds from 290-330 to increase Saturday aftn with ocnl gusts 20-25kts psbl by the evening. Outlook... Sat...MVFR/snow showers developing wrn 1/3; VFR central-east. MVFR to IFR -SN psbl LNS ~12-18z. Sun...Snow showers with IFR/MVFR vsby lkly BFD and JST. Mon...No sig wx expected. Tue...MVFR/IFR. Mixed precipitation lkly. LLWS. Wed...Rain/snow showers. Cold fropa. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...La Corte LONG TERM...Watson AVIATION...Steinbugl
Area Forecast Discussion
National Weather Service Quad Cities IA IL
304 PM CST Fri Jan 6 2017 .SYNOPSIS... Issued at 303 PM CST Fri Jan 6 2017 18Z surface data has arctic high pressure from the southern Plains into the western Great Lakes. A weak Alberta clipper was over southwest North Dakota. Dew points were in the single digits above and below zero over the Midwest. Dew points in the teens and higher were across the Tennessee Valley and the deep South. && .SHORT TERM...(This Evening through Saturday) ISSUED AT 303 PM CST Fri Jan 6 2017 The first of two weak upper level disturbances will move through the area late this afternoon and early evening. The dry atmosphere is helping to slowly dissipate clouds so there may or may not be some isolate flurries in the highway 20 corridor. A mix of clouds and clear skies during the evening combined with light winds should allow temperatures to initially plummet this evening. Trends from the RAP model indicates the second upper level disturbance will have a weak low associated with it when moves through the area late tonight and Saturday morning. Moisture is limited with the second disturbance. However, there is some respectable forcing. This forcing should allow a band of flurries to develop late tonight into Saturday morning as the system moves through the area. In the Dakotas this morning, the same weak system was also producing light snow or snow showers. Thus I would not be surprised if patches of light snow or snow showers develop late tonight into Saturday morning as the system moves through the area. If bona fide light snow or snow showers develop late tonight, a localized dusting of accumulation is not out of the question. Any lingering flurries or light snow that develop tonight will end by mid to late Saturday morning followed by decreasing clouds. Temperatures tonight and Saturday will continue to average well below normal. .LONG TERM...(Saturday Night through Friday) ISSUED AT 303 PM CST Fri Jan 6 2017 Northwest flow will keep cold, but moderating, temperatures in place through the weekend. System for early next week is trending further north, which would lead to less precipitation and likely primarily a light rain event for the forecast area. Saturday night, the high pressure at the surface is expected to pass overhead toward 12z Sunday morning, with subsidence and dry air aloft setting up ideal conditions for another night of subzero temperatures. As seen this morning, the coldest temperatures should be over existing snow cover in the far north and southern counties and have maintained lows below guidance from around 5 below north to around zero central and south. While still below normal, Sunday will be comparatively warmer with developing southerly winds and filtered sunshine. Model runs over the past 24 hours have trended further west and northwest with the track of low pressure lifting through the region Tuesday. The wing of warm advection precipitation depicted in earlier model runs well ahead of the system should now stay well to the north, leading to a dry, but cloudy Monday with temperatures climbing into the upper 20s to mid 30s. Increasing moisture, along with isentropic lift and mid level forcing ahead of the advancing shortwave should lead to light precipitation developing overnight. For now, this is mentioned as initially snow changing to rain from south to north as warm air advection and breezy south winds boost the low levels well above freezing with advertised lows in the upper 20s to mid 30s likely occurring Monday evening. Current indications suggest any snow at the onset would be brief, followed by a high pop/low qpf event through Tuesday morning as the system tracking through central or western IA would spread the bulk of its precipitation well north of the area. As colder air wraps around, a band of snow may accompany the cold front that sweeps through late afternoon and evening with little accumulation suggested. Temperatures then plunge back into the teens and 20s overnight after reaching well into the 40s in most areas during the day. Wednesday through Friday: An active, mostly zonal flow follows with another system late Wed into Thu. Forecast models are in poor agreement with the timing and track of the surface low, varying from either over or just west of the forecast area, to the Ohio River Valley, offering a low confidence forecast. This leads to an extended period of low pops and temperatures near climo Thu and Fri, followed by colder temperatures Friday, where models come back into agreement with cold high pressure building in from the northern plains. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) ISSUED AT 1129 AM CST Fri Jan 6 2017 Developing diurnal clouds may create areas of MVFR conditions across eastern Iowa and northern Illinois through 22z/06. Otherwise expect VFR conditions through 06z/07. After 06z/07 a weak upper level disturbance will move through the Midwest. This disturbance looks to produce flurries and possibly snow showers across eastern Iowa and northern Illinois. Although not included in the 18z TAFs, there is a low risk of MVFR conditions developing that might impact a TAF site. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...08 SHORT TERM...08 LONG TERM...Sheets AVIATION...08
Area Forecast Discussion...Updated
National Weather Service Peachtree City GA
945 PM EST Fri Jan 6 2017 .Update... Winter weather event underway at this time. Snow accumulating over portions of north GA...with transition to freezing rain and sleet south metro Atlanta. Snow line should continue to push southward overnight. No changes to the current forecast. 41 .Previous... ...SIGNIFICANT WINTER STORM UNDERWAY... .SHORT TERM /Tonight through Saturday Night/... Significant winter weather event unfolding across the area this afternoon. First in a series of shortwaves located along LA coast is helping to pump plenty of moisture into the SE...while a strong arctic airmass at the sfc is filtering cold air into the CWA. Radar imagery is showing a broad swath of precip across the state...with a combination of ASOS obs...Mping reports...and phone calls indicating a mixture of snow and sleet across far north Georgia...mixture of rain and sleet towards metro ATL...and mostly rain further south. Expect precip coverage to continue with conditions deterioratingfor the remainder of today and tonight. So far today...WRF4km...NMM...and HRRR seem to have the best handle on have adjusted temps...POPs...and Wx grids towards these solutions. So far things are going as planned. Forecast soundings are showing a much stronger warm nose than initially expected. Unfortunately this will cause more of an ice/sleet concern than snow for many. Big change to the forecast was to emphasize that ice accumulations could reach over a quarter of an inch...generally near areas along the I-85 corridor. Main forecast trends are as follows: The transition to snow will occur most quickly across far N Georgia. With arctic air plunging in...this transition should be underway by 20z. N Georgia foothills into north metro ATL will see an initial mix of rain/freezing rain/sleet...with a predominant change to sleet/wet snow this evening and then all snow by midnight. Metro ATL into areas just south will see a longer period of rain/freezing rain/sleet mix before the transition to more sleet and then all snow. Areas into central Georgia expected to be predominately a mix of rain/sleet/freezing rain or all rain. Concern overnight will be banded snow along deformation zone...with HRRR...NMM...and WRF4km showing multiple bands developing by midnight. Right now think heaviest banding will develop north of a line from Carrollton to Marietta to Commerce. A shortwave/currently located over TX panhandle/ progged to quickly dart through the state overnight will sustain these bands...and push them southeast...allowing accumulations to become possible all the way south from Lagrange to Griffin to Elberton. These bands will be capable of dumping an inch or two of snow /or more/ an hour due to the intense dynamics in place. For this reason...have placed highest snow swath of between 4-6 inches/ with locally higher amounts/ from Carroll County northeast up through Towns/White county. Snow should end from west to east by Saturday morning...where concerns then turn toward wind chills and cold temperatures. Wind chill advisory criteria will be met on Saturday...mainly across far north Georgia...where values will dip below zero. Accumulations of ice/sleet/snow will likely cause travel impacts on Saturday. Please exercise caution and opt to not take an unnecessary risk. With it being a is a good idea to stay home and keep warm. Please keep in mind that exact locations of heaviest snow and ice are subject to change/difficult to forecast exactly as we continue to monitor trends/latest available data. Confidence is very high on conditions deteriorating quickly with time. Kovacik && .LONG TERM /Sunday through Friday/... No wholesale changes made for fcst period as looks mainly in line. Previous discussion follows... Baker PREV DISCUSSION... /Issued 443 AM EST Fri Jan 6 2017/ LONG TERM /Sunday through Thursday/... Quiet but cold weather to start the long term as dry surface high pressure builds to the central to southern Appalachians on Sunday. Forecast high temperatures are expected to run around 15 degrees below normal. Dry weather expected to continue on Monday but moisture returns by Tuesday with mainly small chances for light rain over n GA in the overrunning type flow. Rain/shower chances go up Tuesday night and Wednesday for n and portions of central GA as a cold front moves into the area Wednesday morning. Not much instability with this front so far so only showers associated. The front looks to stall across the area so mainly small rain chances continue on Thursday for n and portions of central GA. High temperatures begin to warm on Monday and continue to warm to around normal on Tuesday then above normal for Wednesday and Thursday. BDL && .AVIATION... 00Z Update... Rain/sleet/snow mix this evening becoming freezing rain/sleet/snow before changing to mostly snow after 06z. Ceilings mvfr becoming ifr during the evening. Precipitation ending by around 18z Saturday with improving ceilings. Winds will be north to northwest around 10 to 12 kts...increasing to 15 to 25kts overnight through tomorrow morning. //ATL Confidence...00Z Update... Medium on timing of precip type. High on remaining elements. 41 && .PRELIMINARY POINT TEMPS/POPS... Athens 29 36 17 37 / 100 50 0 0 Atlanta 21 31 16 36 / 100 30 0 0 Blairsville 15 27 9 33 / 100 30 0 0 Cartersville 17 31 13 35 / 100 20 0 0 Columbus 25 37 20 42 / 100 20 0 0 Gainesville 23 32 15 35 / 100 40 0 0 Macon 32 39 20 42 / 100 50 0 0 Rome 17 31 14 35 / 90 20 0 0 Peachtree City 21 33 17 37 / 100 30 0 0 Vidalia 39 42 25 42 / 100 80 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 1 PM EST Saturday for the following zones: Banks...Barrow...Bartow...Butts...Carroll...Cherokee... Clarke...Clayton...Cobb...Coweta...Dawson...DeKalb...Douglas... Fayette...Forsyth...Greene...Gwinnett...Hall...Haralson... Harris...Heard...Henry...Jackson...Jasper...Lamar...Lumpkin... Madison...Meriwether...Monroe...Morgan...Newton...North Fulton... Oconee...Oglethorpe...Paulding...Pickens...Pike...Polk... Putnam...Rockdale...South Fulton...Spalding...Talbot... Taliaferro...Troup...Upson...Walton...White...Wilkes. Winter Storm Warning until 1 PM EST Saturday for the following zones: Catoosa...Chattooga...Dade...Fannin...Floyd...Gilmer... Gordon...Murray...Towns...Union...Walker...Whitfield. && $$ SHORT TERM...41 LONG TERM....BDL/Baker AVIATION...41
Area Forecast Discussion
National Weather Service Goodland KS
744 PM MST Fri Jan 6 2017 .UPDATE... Issued at 742 PM MST Fri Jan 6 2017 Just completed an update. For now the winds are holding temperatures up in the west. There is a lot of variability in temperatures. With temperatures not too far above the forecast mins, despite the wind, decided to lower those temperatures a little. Have not reached wind chill advisory CRITERIA yet but are getting close. && .SHORT TERM...(This evening through Saturday) Issued at 210 PM MST Fri Jan 6 2017 Early afternoon WV imagery and RAP upper level analysis shows shortwave trough over Kansas and the Southern Plains moving eastward with NW flow building over our CWA. A surface trough extends across the western part of our CWA, with high pressure sliding east- southeast. Tonight-Saturday: Large scale subsidence and a dry air mass will support dry conditions through these periods. High clouds may increase during the day Saturday afternoon as weak vorticity rotates through NW flow aloft. Regarding temperatures/wind chills: West-southwest flow associated with lee trough in CO will continue to support moderating temperatures through the short term periods. Snow pack will complicate temperatures with better cooling tonight and slower diurnal heating during the day where deeper snow pack is in place. Clear skies, light winds, and lingering snow pack will support efficient diurnal cooling and the air mass will still be cold enough for negative temperatures to develop once again tonight/Saturday morning. It will not be quite as cold as this morning and winds will be light, but this will still be enough to lower wind chills to -15F (or lower) in our CO/NE counties supportive of a Wind Chill Advisory. Current forecast is very close to advisory in adjacent KS counties, but snow pack may result in even lower temperatures than what is currently forecast. It was close enough, so I decided to include an extra row of counties for the advisory. .LONG TERM...(Saturday night through Thursday) Issued at 1200 PM MST Fri Jan 6 2017 Saturday night through Friday...general theme is for warming temperatures Sunday and Monday as an upper level ridge slowly moves over the area. There will be periods of increasing and decreasing clouds with no precipitation expected. An upper level trough moves across the area late Monday night through Tuesday morning bringing some cooler temperatures and perhaps breezy northwest winds to the area. Near zonal flow expected Wednesday with continued above normal temperatures. Cooler then colder air moves in for Thursday and Friday. We could see some light snow as an upper trough moves across the area. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 441 PM MST Fri Jan 6 2017 Vfr conditions and light winds will prevail through the period. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Wind Chill Advisory until 9 AM MST /10 AM CST/ Saturday for KSZ001>004-013-027. CO...Wind Chill Advisory until 9 AM MST Saturday for COZ090>092. NE...Wind Chill Advisory until 9 AM MST /10 AM CST/ Saturday for NEZ079>081. && $$ UPDATE...BULLER SHORT TERM...DR LONG TERM...99 AVIATION...BULLER
Area Forecast Discussion
National Weather Service Wilmington OH
944 PM EST Fri Jan 6 2017 .SYNOPSIS... A ridge of Arctic high pressure will continue to extend into the region tonight and Saturday. A weak trough of low pressure will pass across the Great Lakes Saturday night. The Arctic high will then become reestablished on Sunday before moving off to the east by Monday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Stratocu deck has all but gone away this evening but extensive cirrus remain across the CWA. Latest runs of the NAM/ GFS/ RAP all try and scatter out the cirrus overnight into Saturday morning leaving mostly clear skies across the region. Looking at current conditions models appears to be clearing the cirrus out to quickly. Have trended sky cover higher through the night. Low temperatures tonight will be tricky as there are many competing factors. The fresh snow pack would promote better radiational cooling while the surface high pressure off to our west (keeping the pressure gradient just tight enough for a light wind) along with cirrus would promote warmer overnight lows. Given the overall above and thinking that cirrus will eventually clear out have kept forecast trended below guidance. This means that urban areas will likely observe single digit low temperatures will some rural spots will likely observe below zero single digits. These very cold low temperatures means wind chills will be very close to advisory criteria. This is again marginal for an advisory as winds are expected to remain at or below 5 mph. Have continued to cover this with a Special Weather Statement. High temperatures Saturday will be in the teens as 850 mb temperatures are only forecasted to rise to 15 degrees below zero. Given the snow pack and mixing only to 925mb have kept forecasted high temperatures slightly below guidance (or a degree or two above Thursday high temperatures). Prev Discussion-> Stratocumulus along with extensive high clouds remain across the region this afternoon. There have been some very light flurries falling out of the stratocumulus. The lower clouds along with the flurries should diminish late this afternoon. High clouds will take longer to clear, but should do so in the latter half of the night. Winds will weaken a bit but not go calm. So not ideal radiational cooling, but given how much temperatures dropped this morning, have opted to shade on the cool side of guidance. Wind chill readings will be flirting with the -10 threshold in some areas by morning. This is marginal for an advisory, especially with the wind expected to be light. So have covered the cold conditions with a Special Weather Statement. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Surface ridge that has been extending into the are will remain through Saturday and then get suppressed as a trough swings across the Great Lakes. At most this trough may bring some additional clouds to the northern counties Saturday night into Sunday morning. After the trough passes, the center of the high will finally track across Kentucky on Sunday with winds turning southerly Sunday night as the high moves off to the east. Very cold temperatures will persist through the weekend. Kept forecast temperatures a bit below MOS numbers through the period. Looks like lows on Sunday night will be early with readings rising through the teens later in the night. && .LONG TERM /MONDAY THROUGH FRIDAY/... Models continue to be in good agreement for a large portion of the long term with the general pattern and therefore continued to go close to the superblend for most of the forecast. Several systems are expected to move through during the long term period, however expect dry conditions to start out the long term on Monday. High pressure will be east of the area and southerly flow will be present. This will allow temperatures to warm into the 30s on Monday. Although this is still only close to normal temperatures for this time of year, it is much warmer than previous days. Dry conditions come to an end Monday night into Tuesday as moisture begins to work into the region. A mix of precipitation is possible Monday night into Tuesday morning before a surge of warm air and a changeover to all rain occurs on Tuesday. The best precipitation chances are Tuesday night as a cold front moves through the region. Models have been very consistent with bringing this feature through Tuesday night. Went with high precipitation chances Tuesday night due to this. A brief mix of precipitation will be possible at the tail end of the event before precipitation tapers off Wednesday morning. Dry conditions will be short lived since by Wednesday night another system will bring precipitation chances back in the forecast. Rainfall chances increase for Thursday and Friday as a boundary approaches and lays out over the area. Although models agree on this boundary, there are some slight differences on where this boundary will set up. There will be a good gradient in temperatures across the boundary. In addition, if current trends continue this system has the potential for a longer duration widespread rainfall event. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Cirrus blow off continues across the area thanks to an upper level disturbance currently over OK/ TX. There also remain a stratocu deck below the cirrus. Looking at forecast soundings on the NAM and GFS a few to sct stratocu deck in indicated to remain through the issuance. Am a little skeptical of this as PWATs are forecasted to be around 0.07" Saturday. Given this though the PWAT on the 07.00z ILN sounding was only 0.09" (balloon only up to 400 mb so far). 850 mb temperatures are also forecasted to be around -15 degrees C Saturday. Thanks to the above have kept a mention of stratocu in the TAFs while keeping all locations VFR. Winds will also be light Saturday as surface high pressure slowly builds across the region. OUTLOOK...MVFR ceilings are possible from Saturday night through Sunday. MVFR ceilings and visibilities are possible again Tuesday through Wednesday morning && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Haines/ NEAR TERM...Haines/ SHORT TERM... LONG TERM...Novak AVIATION...Haines
National Weather Service Jackson KY
1007 PM EST Fri Jan 6 2017 .UPDATE... Issued at 1007 PM EST FRI JAN 6 2017 The 00Z NAM continued to trend wetter. The NAM was still the driest model, but even it now supports advisory criteria snow at the VA border. With this information, have issued a WSW for our VA border counties. UPDATE Issued at 719 PM EST FRI JAN 6 2017 The update blended latest obs into the evening forecast. Have held off on other changes at this point. Precip will be monitored as it advances toward our region tonight. The models have continued to trend wetter, with the GFS still being the wettest. The GFS supports advisory criteria snow in our far southeast, but the NAM does not. Other models such as the RAP and HRRR fall in between, with advisory criteria near the state line. It`s possible a last minute advisory could be used if things look favorable when 00z model runs start coming in. && .SHORT TERM...(This evening through Saturday night) Issued at 342 PM EST FRI JAN 6 2017 Surface high pressure is centered across the southern Plains, with the ridge axis aligned to the east into the Ohio Valley. Low pressure is poised across the southern Appalachians, with a more defined baroclinic zone set up from the Carolina coast to the northern Gulf of Mexico. Aloft, troughing is aligned from the Great Lakes down to the Desert Southwest, setting up deeper southwest flow across the southeast CONUS. Cold and dry air is in place across eastern Kentucky, with temperatures ranging from the mid teens to lower 20s. Dew points have dropped into the single digits for the northwest half of the area. The models are in good agreement with a dynamic system to affect most of the southeast CONUS tonight into Saturday. The central CONUS trough will move east and deepen. Surface low pressure will organize and move northeast along the baroclinic zone located across the northern Gulf. This will reach the Carolina coast by Saturday. Moisture from this system will return from the south, affecting mainly our southeast counties late tonight into early Saturday morning. Overall, there has been a general trend to bring enough moisture to measure deeper into our area. As such, have raised probabilities to likely for measuring. The gradient for the accumulating snowfall will be tight, with Black Mountain likely receiving up to 2 inches, while most other places measuring less than an inch. Will highlight timing and snowfall amounts in an SPS. Temperatures tonight will range from the single digits north, to the 10 to 15 degree range for the valleys bordering Tennessee and Virginia. On Saturday, moisture will be exiting, with light snow and flurries coming to a quick end across the southeast during the morning hours. Clouds will also be thinning, but despite some sunshine, highs look to only be in the upper teens to lower 20s. More clearing Saturday night will set the stage for another more widespread single digit night for lows. .LONG TERM...(Sunday through Friday) Issued at 343 PM EST FRI JAN 6 2017 The period will start off quiet with Canadian high pressure sinking into the region and high temperatures only climbing into the lower 20s for most. This surface high pressure will be fairly transient, as it progresses to our east by Sunday night. That said the sounding do suggest some mainly high clouds will be possible by late evening in the far western portions of the CWA. Even given this did opt to lower the eastern valleys at a minimum right now given the setup, as it will not take long for those valleys to see quick drops. Now that high pressure is shunted east expect return flow by the time we move into Monday and therefore temps finally climb above freezing for most. Also good agreement for additional high clouds to build east by Monday afternoon. This will be aided by additional moisture that will stream into the region ahead of the next system. Now models continue to come in with decent agreement on the next low pressure system ejecting out of the central plains and into the Great Lakes by the time we get to Tuesday afternoon. A attendant cold front will move east with said surface low. However ahead of the system there could be a brief shot of overrunning and this will lead to potential of a brief shot of snow/rain and snow mix. This snow will have the best chance of occurring in the Bluegrass before the warm air moves into the region. That said the overall best chances of rain area wide will be Tuesday night, and therefore could not argue going above the latest model blend to categorical. This as models have been in decent agreement with only minor timing issues for some time now. There is good agreement that the front will hang up between Ohio and Tennessee Valleys before it tracks back north as a warm front by Wednesday. This will keep at least chance POPs across the region Wednesday into Wednesday night. Now by Thursday there will be a lull in the east and then we see a cold front approach from the west. This frontal boundary will get hung up somewhere along the Ohio River with blocking high setup to the east. Therefore keep better POPs along the Bluegrass and lesser SE of that. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 719 PM EST FRI JAN 6 2017 Initial conditions were MVFR near the VA border, but were mainly VFR elsewhere. An overall deterioration is forecast, with most places becoming MVFR overnight. Some IFR can be expected as well, especially near the VA border. The downturn in conditions will be accompanied by snow near the VA border. Most of the snow should pull out to the southeast by dawn, but low clouds will linger. It`s uncertain how quickly the clouds will break up and exit to the east. For now, have gone pessimistic. However it`s possible VFR conditions could make a comeback during the day Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 7 AM EST Saturday for KYZ087-088- 118-120. && $$ UPDATE...HAL SHORT TERM...GEOGERIAN LONG TERM...DJ AVIATION...HAL
Area Forecast Discussion
National Weather Service North Platte NE
543 PM CST Fri Jan 6 2017 .SHORT TERM...(This evening through Saturday) Issued at 253 PM CST Fri Jan 6 2017 The main forecast challenges during the short term...through Saturday afternoon...are temperatures and wind chills. The snow pack from this week`s event is prominent on visible satellite, with the best signature roughly along and just north of I- 80. Trended tonight`s min temps toward the cooler MET guidance due to the snow pack and partly/mostly clear skies. Lows approach -10 to -12F near the Pine Ridge, eastern panhandle, and Platte River Valley. Winds will be relatively light overnight, generally under 10 mph, as a ridge at H85 approaches. The ridge axis remains just west of the area until morning, which places the forecast area in low level west/northwest flow. Went ahead and issued a Wind Chill Advisory for the aforementioned areas, although this will likely be a marginal event. The lowest readings approach -25F near the Pine Ridge and -20F southwest in the early/mid morning. For north central Nebraska, kept lows near 0F due to increasing cloud cover overnight, the lack of snow cover, and today`s highs reaching the teens. The NAM, GFS, and RAP are consistent with a ribbon of high RH from KVTN to KONL in the 500-700hpa layer with the passage of a weak shortwave. Marginal isentropic lift also exists at 280K. However, forecast sounding analysis shows abundant dry air in the low levels and refrained from introducing PoPs (flurries). Saturday...made little adjustment to max temps. The low level ridge axis progresses east, bringing southerly return flow to the area. Did lower a degree or two where the deepest snow pack remains, but highs may still be overdone. Mid level dry air returns behind the shortwave, so expecting a mainly clear and cold day for the most part. .LONG TERM...(Saturday night through Friday) Issued at 253 PM CST Fri Jan 6 2017 Long term is characterized by a moderately progressive large scale pattern. Beginning Saturday night the large scale pattern will feature a 500 hPa ridge over the western and central US while an amplified trough will be in place over the eastern US. The trough will exit the east coast by Monday while the ridge will become less amplified as it is influenced by another mid-level trough impacting the Pacific Northwest. Over the first 48 hours of the period, Saturday night through Monday, the air mass will see a fair warm up over western and north central NEB aloft with near zero to slightly above zero 850 hPa temperatures overhead Sunday to 850 hPa temperatures 8-16 C overhead by Monday. This will mark a return to near seasonal normal values Sunday and above seasonal normal values by Monday, the latter will feature highs about 10 degrees above normal in southwest NEB Monday afternoon. Quiet weather is expected to prevail through much of Monday. A disturbance moving through the Northern-Central Rockies into the Northern-Central Plains late Monday to early Tuesday morning will lead the development of a low pressure system near the Central High Plains Monday evening that will then move into the southern Upper Mississippi Valley by early Tuesday morning. Late Monday into Monday Night will feature slight chances-chances for snow and rain mixing with snow at times possible Monday afternoon. Chances begin in the afternoon across northwest NEB then spread through the northern Sandhills into far north central NEB Monday Night. The best chances for snow looks to be confined to the Dakotas with this system. The low`s cold front is expected to then track through and be south and east of the local forecast area by early Tuesday morning. While temperatures will experience a slight drop Tuesday, highs will rebound modestly Wednesday before cold air returns to the region beginning late Wednesday-early Thursday. Of note, deterministic guidance beyond Tuesday night begins to show more apparent differences in the large scale pattern that are affecting the details of the cold air`s return. However, current thinking doesn`t divert much from the previous forecast with western and north central NEB expected to see a return to below normal high temperatures Thursday and Friday. Strong high pressure is expected to develop and be over the Northern Plains by late Thursday. A disturbance late Thursday-Friday will bring a return of increased chances for snow to the area. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 541 PM CST Fri Jan 6 2017 SCT to BKN mid level clouds are expected tonight into Saturday morning across northern Nebraska, otherwise mainly clear skies and VFR expected. Winds will be light all areas. && .LBF WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory from 9 PM CST /8 PM MST/ this evening to 10 AM CST /9 AM MST/ Saturday for NEZ004-022-056>059-069>071-094. && $$ SHORT TERM...Snively LONG TERM...ET AVIATION...Taylor
Area Forecast Discussion
National Weather Service Melbourne FL
847 PM EST Fri Jan 6 2017 .UPDATE... ...Increased rain chances into Saturday afternoon... ...Very hazardous marine conditions developing behind cold front on Saturday... ...Turning sharply colder Saturday night through Sunday night... Currently-Saturday...A weak wave of low pressure will move east/northeast along a frontal boundary in the northeast Gulf of Mexico. This wave was pulling a band of higher moisture northward ahead of it and there looks to be a weak warm front acting as a lifting mechanism. Additionally, an impulse aloft was approaching. This has led to a couple of clusters of convection in the eastern Gulf of Mexico, which were moving east/northeast this evening. The 00z Canaveral sounding showed the air mass over east central Florida was still quite dry with precipitable water 1.17 inches. Surface dew points were in the 50s, except along the coast where the afternoon sea breeze boosted values into the lower-mid 60s. However, with the impulse aloft and ongoing surface based convection in the Gulf, think that there is a chance for storms to push well inland and across the peninsula. The HRRR model has been showing the clusters moving across the area and offshore a little after 06z. Therefore, have had to adjust weather grids to bring thunder chances earlier. Once this convection pushes away, there should be a lull for awhile until the low pressure wave moves by to the north and the cold front sweeps down into the area. The HRRR has been showing additional showers/storms just ahead of it. The model indicates most of this will be after 12z Sat, except in the far north. The band of showers/storms should exit our southern areas a little after 18z. With strengthening wind fields, showers/storms will be moving quickly. But limited surface instability should result in the main hazard being from lightning strikes. Sat will be cloudy most of the day with breaks indicated only in the north late. Breezy northwest winds will advect cold air into the north early and limit highs to around 60, with readings actually falling during the afternoon. The far south should reach the mid 70s before the front sweeps through in the afternoon. && .AVIATION...Scattered-numerous showers will spread across most of the terminals from about 02-07z. There is also a slight chance for embedded thunderstorms. A cold front will then sweep down from the peninsula and bring a chance for showers/storms from about 09z in the north to 18z in the far south. Mainly MVFR conditions are expected, though a few showers or storms could produce brief IFR visibility. Behind the front, northwest winds will be around 15 knots with gusts at or slightly greater than 20 knots. Did not include low level wind shear in the forecast, but this will probably be needed after 06z until about 12-13z, as boundary layer winds increase, while stability at the surface keeps winds much lighter. && .MARINE... Tonight-Saturday...Boating conditions will become very hazardous for small craft behind a cold front that moves through the northern waters early Saturday and southern waters early Saturday afternoon. Pre-frontal southwest winds late tonight and early Saturday will also be around 20 knots and gusty to 25 knots well offshore. Mariners should not judge whether to go out into the Atlantic early Saturday based on conditions at port where southwest winds will be lighter! A small craft advisory will be in effect around sunrise. Gale conditions are expected to develop behind the cold front by Sat afternoon offshore, and even for the nearshore waters by late in the day as winds veer to northerly. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Gale Watch from Saturday afternoon through Sunday evening for Flagler Beach to Volusia-Brevard County Line 0-20 nm- Sebastian Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20 nm. Small Craft Advisory for winds from 7 AM to 4 PM EST Saturday for Flagler Beach to Volusia-Brevard County Line 0-20 nm- Sebastian Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20 nm. Gale Watch from Saturday morning through Sunday evening for Flagler Beach to Volusia-Brevard County Line 20-60 nm- Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. && $$ Lascody/Volkmer
Area Forecast Discussion
National Weather Service Raleigh NC
1105 PM EST Fri Jan 7 2017 .SYNOPSIS... A low pressure system will track northeast up the Atlantic coast tonight in advance of an upper level disturbance approaching from the west. && .NEAR TERM /THROUGH Saturday/... As of 1100 PM Friday... A somewhat atypical winter weather event --but what is nonetheless expected to be a significant one for a large part of central NC-- is beginning to unfold. WV imagery indicates the flow aloft continues to back over the Southeastern U.S., downstream of a potent nrn stream shortwave trough now pivotting across the ArkLaTex, and a more subtle lead wave over the Deep South. These waves will move E into the TN Valley and Srn Appalachians, respectively, by 12Z Sat. A surface low over the NE GOM has strengthened slightly to around 1009 mb as it nears the Big Bend of FL; and this low will further consolidate as it tracks NEwd along a srn stream frontal zone, to just offshore the NC coast by 12Z Sat. To the N, the backdoor segment of an arctic front --which roughly corresponds to the wet bulb freezing line-- has settled into the nrn Coastal Plain and NErn Piedmont, and intersects the SW to NE-oriented arctic frontal segment extending across the NC Wrn Piedmont SWwd to just west of the aforementioned GOM surface low. The presence and location of the arctic front, and associated strengthening wedge over VA and nrn NC and non-miller A pattern of cyclogenesis characteristics, has 1) already delayed the transition from rain over all but the NWrn third of the CWA and 2) introduces a greater probability of icing --mostly sleet, but with around a tenth to quarter inch of freezing rain from near Lillington to Smithfield to Rocky Mount and Goldsboro. As this front continues to collapse SEwd into the frontal zone and primary cyclone tracking up the Southeast U.S. coast, frontogenetical forcing will increase (lift), and cooling low levels from both advection and melting (heavy precipitation rates) will cause the rain/sleet/snow line to likewise collapse, into the Coastal Plain and Sandhills by 12Z. The main change from the previous forecast has been to slightly reduce snow/frozen totals roughly south of a line from Rockingham to Garner to Rocky Mount, where boundary layer (wet bulb) temperatures have and will continue to favor a longer duration tonight of mostly rain, mixed at times with sleet, and also where periods of sleet late tonight sleet will cut into frozen/snow totals even as the boundary layers cools to and below freezing. In what is expected to be the all or mostly snow area over the Nrn Piedmont, where the 00Z GSO RAOB sampled an extremely favorable snow profile, currently advertised "Most Likely" snow totals may be conservative given the wetter trend in recent NAM and RAP runs. The recent wetter solutions may indeed be on to something, given the aforementioned favorably juxtaposed QG and mesoscale forcing for ascent. An approximately 00Z sounding from the NCSU sounding club sampled an approximately 2 C warm nose at 800 mb; and both the recent NAM and RAP/HRRR runs suggest this warm nose may oscillate about Wake Co. through much of the night. This data suggest an even sharper gradient in frozen totals is likely to be directly over the Triangle, with just a few inches over srn Wake Co. and perhaps close to a foot (or more) across Durham and Granville Co. && .SHORT TERM /Saturday night through Sunday night/... As of 110 PM Friday... A very cold air mass will settle over the region Saturday night. Where snowpack is deepest, expect daytime highs 30-32F. Overnight temperatures 5 to 15 above zero both nights with minimum cloud cover and light winds. Isolated spots Sunday night may bottom out around zero or slightly below where the deepest snow cover remains. Black ice will be likely Saturday night and Sunday night on many roads. && .LONG TERM /MONDAY THROUGH FRIDAY/... As of 135 PM Friday... With a strong 1043mb high centered directly overhead Monday, we will see ample sunshine under strong subsidence, but return flow and warm advection holds off until Tuesday, so highs will reach the lower 30s Monday and finally the lower 40s on Tuesday. Monday night lows will moderate a little but still be in the teens. It appears the airmass will recover enough to remove any chances of wintry precip Wednesday morning when the next round of precip will start to arrive. A southern stream shortwave will lift across the interior US early next week bringing a chance of showers to the region Wednesday and Wednesday night. A ridge will build across the Southeast Thursday and Friday as a trough digs in the central United States. This will result in temperatures into the 60s Thursday and Friday with dry conditions. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 640 pM Friday... Precip has spread across central NC this afternoon, varying from mainly snow at INT/GSO, to a mix of rain and sleet at RDU, and rain at RWI/FAY. While the precip is light this evening, these precip types and mostly MVFR ceilings should be fairly common, through around 03Z. After 03Z, heavier precip will spread across the area as an area of low pressure begins to form off the Southeast coast All terminals should see IFR ceilings overnight. We expect all snow at INT and GSO, with periods of heavier snow and LIFR possible between 06Z and 12Z, then ending by 15Z At RDU, precip will be a mix of snow and sleet for a large portion of the time, changing to all snow by 12Z and essentially ending by around 17Z. At RWI, Sleet may be more predominate overnight, mixing with freezing rain and then changing to snow around 12Z. precip will last longest at RWI, ending around 18Z FAY is more likely to see all rain until around 09Z, when temps may become cold enough for sleet and freezing rain through about 14Z. Once precip ends saturday morning, conditions will improve to VFR from west to during the afternoon. Outlook: Arctic high pressure will settle in behind the exiting winter storms, providing us with VFR conditions Sunday through Tuesday. && .CLIMATE... Upcoming record daily minimum temperatures... Greensboro (KGSO) January 6...5 set in 1924 January 7...5 set in 2014 January 8...6 set in 2015 January 9...2 set in 1970 Raleigh/Durham (KRDU) January 6...7 set in 1924 January 7...9 set in 2014 January 8...7 set in 1970 January 9...0 set in 1970 Fayetteville (KFAY) January 6... 8 set in 1924 January 7...12 set in 2014 January 8...13 set in 2015 January 9... 9 set in 1970 Upcoming record daily snowfall... Greensboro (KGSO) January 6...6.0 inches set in 1996 January 7...8.6 inches set in 1988 Raleigh/Durham (KRDU) January 6...2.7 inches set in 1996 January 7...7.1 inches set in 1988 && .RAH WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 7 PM this evening to 7 PM EST Saturday for NCZ007>011-021>028-038>043-073>078-083-084. Winter Weather Advisory from 7 PM this evening to 7 PM EST Saturday for NCZ085-086-088-089. && $$ SYNOPSIS...Vincent NEAR TERM...MWS SHORT TERM...WSS/KCP/Franklin LONG TERM...BLS/Franklin AVIATION...WSS CLIMATE...Franklin
Area Forecast Discussion
National Weather Service Charleston WV
948 PM EST Fri Jan 6 2017 .SYNOPSIS... Arctic air dominates this weekend as low pressure passes to the southeast clipping the southern and eastern zones. High pressure for Monday. A couple of systems provide precipitation for Tuesday through Friday. && .NEAR TERM /THROUGH SATURDAY/... As of 940 PM Friday... Per latest model guidance, opted to hoist a Winter Weather Advisory for SW VA and Southern WV counties where they could see 1-3 or maybe even 2-4 inches of snow as a band of snow sets up overnight. Excess moisture is being pulled north by a mid level wave and a stream of saturated 700 mb moisture is being advected into a strong dendritic growth zone, so snowfall rates may be high in the inch an hour range overnight tonight. Could have probably extended this to Wyoming and Fayette counties, but uncertainty is a little higher there due to the sharp gradient in snowfall that should result from straddling the counties, i.e. the western portion may see little snow while the eastern portions may see 2 or more inches. As of 700 PM Friday... Opted to increase PoPs and thus snowfall over zones southeast of Charleston and Clarksburg. HRRR guidance is trending more towards the snowy GFS. Also noted was a wave on satellite imagery over western Tennessee that has a trajectory that may help to pull a little more moisture to the north from the large system down south. Despite these changes, still hard pressed to reach advisory amounts, but still something to keep an eye on overnight. As of 210 PM Friday... For the immediate term...light snow from the sheared vorticity max is exiting southwest VA and the southern mountains. Lull in the activity will be relatively brief until effects from the Carolina winter storm reach the same area. Models still different in the northwestward extent of moisture and ultimate QPF into the far southern zones and into the Greenbrier Valley. NAM is less aggressive, as are the HRRR and the RAP models, which just clip these counties and produce an event total tonight and early Saturday of roughly an inch or less. GFS, however, paints a snowier picture, with output of multiple inches in places like BKW. Have gone with the more conservative route, along with WPC guidance which gives less than advisory criteria snow. No headlines for this issuance. From a temperature standpoint, going a couple degrees lower than previous forecast for tonight, and hopefully have done a better job with the far northwestern zones, especially Perry and Morgan counties, where the sky will better allow radiative cooling with snow on the ground. Poor temperatures recovery expected again Saturday, with a few locations hitting 20F only. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 330 PM Friday... With arctic air in place and northwest winds, will keep flurries Saturday evening where clouds exist. Deeper moisture arrives in the WV mountain upslope areas later Saturday night into Sunday, providing a chance of some light snow. With the arctic air and decent northwesterly winds, wind chills become an issue in the higher elevations. Will issue a wind chill advisory for the higher elevations of the northern WV mountains for Saturday night into Sunday. May need to expand this into the central and southern mountains as the event approaches. High pressure then builds in Sunday night and Monday. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 330 PM Friday... A warm front may provide a mix of precipitation types for Monday night into Tuesday, depending on the timing of the precipitation. This will be followed by a weak cold front Tuesday night or Wednesday. Timing of this system has varied considerably on the models, so confidence in the timing is not high. Yet another system arrives on Thursday. Operational models are showing a cold front stalling over the area and remaining into Friday. Once again, confidence in this scenario is fairly low. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... As of 945 PM Friday... A winter storm system to the southeast will move low level moisture into the mountains and adjacent lowlands tonight for MVFR conditions. For BKW, snow should bring IFR overnight. Conditions improve to VFR Saturday. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY... FORECAST CONFIDENCE: Medium to high. ALTERNATE SCENARIOS: More moisture could move northward for more IFR in snow. 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 SAT 01/07/17 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 H H H M M M M M M H H L HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H M L L L L L M M L L L EKN CONSISTENCY H M H M H L L L M H M L PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 00Z SUNDAY... No widespread IFR conditions expected at this time. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...Wind Chill Advisory from 7 PM Saturday to 1 PM EST Sunday for WVZ522>524-526. Winter Weather Advisory until 10 AM EST Saturday for WVZ033. OH...None. KY...None. VA...Winter Weather Advisory until 10 AM EST Saturday for VAZ003- 004. && $$ SYNOPSIS...RPY/JW/SL NEAR TERM...JW/26 SHORT TERM...RPY LONG TERM...RPY AVIATION...JW/26