Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/08/19

Area Forecast Discussion
National Weather Service Quad Cities IA IL
926 PM CST Thu Mar 7 2019 .UPDATE... Issued at 915 PM CST Thu Mar 7 2019 Based on new data and trends, any chance of freezing drizzle occurring rest of tonight would be most favored across the far southern counties. Therefore, I`ve removed another tier of counties from the advisory...roughly areas south of I-80 and north of Burlington. Still some uncertainty on whether freezing drizzle will occur in the far south, as not many reports with satellite also showing opportunity for more in cloud ice for at least part of the overnight. But still some slick spots from the earlier snowfall possible far south in addition to a chance of freezing drizzle, thus will keep ongoing advisory for now Burlington on southward. Main roads in Iowa are reported as seasonal driving but still a few slick spots possible on those secondary or untreated roads far southeast Iowa into northeast Missouri, and also west central Illinois where report of patchy covering in Hancock Co. UPDATE Issued at 755 PM CST Thu Mar 7 2019 Short term trends and looking drier rest of tonight with weak ascent atop drier easterly low level flow, with mainly just some flurries in limited low level moisture depth. This drying trend continues bearing out in trends of past several runs of HRRR, and other short term guidance. DVN 00z RAOB moisture depth is limited with notable drying below 2-2.5kft thus casting uncertainty on any drizzle, except perhaps portions of southern counties where some lowering cloud bases exist of around 1kft and some weak WAA persists. Per diminishing trends for any additional accums of snow and non-favorable moisture depth for freezing drizzle, and with latest clear road report most of E IA and IL I`ve cancelled the winter weather advisory for the I-80 corridor. Have kept it going in the south for now where some chance for patchy freezing drizzle is possible, and continue to monitor trends for any additional cancellations. && .SYNOPSIS... Issued at 319 PM CST Thu Mar 7 2019 18Z surface data has high pressure from the Ohio Valley into the upper Midwest as a storm system continues to develop in southeast Colorado. Dew points were in the single digits and teens from the Great Lakes into the northern Plains. Dew points in the 20s and higher ran from the Ohio Valley into the central Plains on south to the Gulf Coast. && .SHORT TERM...(This Evening through Friday) ISSUED AT 319 PM CST Thu Mar 7 2019 Bottom Line Up Front Will keep the current headlines as is. There are questions whether or not any freezing drizzle will be seen in the I-80 corridor tonight. However, given the two significant metro areas along I-80 will keep those headlines going for now. Further south DOT reports show slick roads in southeast Iowa so those headlines look ok. Late this afternoon and tonight The dry air continues to win across roughly the northern half of the area but the forcing and moisture have made inroads up to I-80 west of the Quad Cities in the form of a band of snow that is slowly moving east. RAP trends has the band in the I-80 corridor making slow progression to the east through late afternoon and gradually weakening by early evening. Thus overall snowfall intensity in the band will decrease with time. Further south overall snowfall intensity will continue to weaken through sunset. Tonight, as the atmosphere aloft dries out another round of forcing will move through the area. While not completely certain, there a mixture of freezing drizzle and very light snow should develop in the near saturated lower atmosphere. The area favored to see ice accumulation is generally south of I-80. These amounts would be under 0.10 inches. In the I-80 corridor a light glaze may or may not occur. Any additional snowfall tonight would be a dusting at best. After midnight the forcing moves east of the area. Thus any mixed precipitation will end from west to east with areas west of the Mississippi generally dry by sunrise Friday. On Friday any lingering snow/freezing drizzle mix will end by mid- morning leaving dry conditions for the rest of the day. The clouds will persist all day as a layer of moisture will remain trapped below a warm layer aloft. .LONG TERM...(Friday Night through Thursday) ISSUED AT 319 PM CST Thu Mar 7 2019 Active pattern into next week will feature two strong storm systems capable of widespread significant rain, along with relatively warmer temperatures throughout. Friday night through Saturday night: Latest models have come into close agreement with the upper low currently off the west coast phasing with energy in the northwest, spinning up a lee cyclone Friday. This surface low lifts northeast from KS through central Iowa Saturday, into northern Lake Mi Saturday night. At the upper levels, a negatively tilted trough concentrates an axis of strong lift advancing northeast through the the forecast area Saturday, especially through midday. With PW values unseasonably high in the .75 to 1 inch range, this will likely send an axis of moderate to locally heavy showers through the area. The fast movement of this band should keep QPF in close to what model consensus has, or roughly in a .5 to 1 inch range during the day. The strong upper level forcing along with steep mid level lapse rates will sufficient to produce at least scattered thunderstorms, which are kept in the forecast. Ahead of this, late Friday night, an initial round of strong 850 mb warm advection will bring in light rain or drizzle from southwest to northeast well after midnight. With surface temperatures initially close to freezing, will have a low confidence mention of freezing drizzle or light freezing rain north of I-80. Temperatures should be nearly steady or even rise through the 30s on strengthening brisk southeast winds. Saturday night: The trailing dry slot will end the precipitation or perhaps change it to light drizzle. Colder air wrapping into the area from the west and only shallow moisture lingering will likely end the precipitation before temperatures fall below freezing. Strong westerly winds in the tight pressure gradient may push advisory criteria with models conservatively suggesting 20 kts sustained and 35 to 40 kts or greater gusts, looking at winds at the top of the mixed layer late Saturday night into Sunday morning. High pressure then follows for Sunday night into Monday with another somewhat similar storm system setting up for Tue into Wed. Current model trends have this tracking further northwest than the weekend system and this would again be largely a rain maker with strong winds. Based on low confidence thermal profiles, this is advertised to start as snow in the initial warm advection band early Tuesday. The bulk of the system would be rain and possible thunderstorms with the strongest upper forcing Wed. With similar PW values as the weekend system, this could bring another round of .5 to over 1 inch of rain, which could contribute to river flooding as the hydro system will be primed from the weekend rain. Wednesday`s highs, from the mid 40s to mid 50s, may indeed be too cool, deepening on the timing and track of the low. Thursday looks a bit cooler with another round of light precipitation possible in the afternoon as a lobe of vorticity is shown rotating around the backside of Wednesday`s upper trough to the east. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) ISSUED AT 537 PM CST Thu Mar 7 2019 MVFR to occasional IFR with bouts of light snow and possibly freezing drizzle expected at BRL tonight. MLI, CID and DBQ will start the evening VFR and expect lowering to MVFR especially at CID and MLI, with a few flurries/very light snow and patchy freezing drizzle possible. Much more uncertainty at DBQ on timing of MVFR conditions due to drier air. Generally MVFR to VFR conditions for CIGs expected on Friday. && .HYDROLOGY... Issued at 1217 PM CST Thu Mar 7 2019 Ice jams and ice action continue to impact the Rock River, especially from the Lyndon/Prophetstown areas downstream to Joslin. Emergency management confirmed this morning that the high water remains in place with flooding of farm land and water approaching the edge of route 78 in the vicinity of Lyndon and Prophetstown. An Areal Flood Warning thus remains in effect for the stretch of the river from Lyndon downriver to Hillsdale, along the Rock Island county border. High resolution satellite imagery from Wednesday suggested there may be several ice jams and ice impacts along the river. At Joslin, a Flood Watch remains in effect for both the potential for ice jam flooding and also possible rises above flooding from rainfall events this weekend and next week. Potential rainfall of .5 to 1 inch from each of the next two storm systems will extend the threat of flooding to all tributary rivers and possibly the mainstem Mississippi as well. Ice jams and ice action may also plague the remaining tributary rivers as well. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Winter Weather Advisory until 6 AM CST Friday for Des Moines- Henry IA-Jefferson-Lee-Van Buren. IL...Winter Weather Advisory until 6 AM CST Friday for Hancock- Henderson-McDonough-Warren. MO...Winter Weather Advisory until 6 AM CST Friday for Clark-Scotland. && $$ UPDATE...McClure SYNOPSIS...08 SHORT TERM...08 LONG TERM...Sheets AVIATION...McClure HYDROLOGY...Sheets
Area Forecast Discussion
National Weather Service Hastings NE
948 PM CST Thu Mar 7 2019 .UPDATE... Issued at 945 PM CST Thu Mar 7 2019 Had to add some mixed wintry precip in our far south into the early overnight. Also, fog is a bigger concern as both LAMP data and HRRR seem to focus at least our northwest quarter of the CWA with fog potential as our stratus builds down. I beefed up the fog wording in the HWO and in the forecast, but held off from the fog advisory as both LAMP and HRRR were too aggressive at initiation, and I suspect that dense fog will be more spotty and local in nature, but this is a situation that must be monitored as sites may drop to one quarter or less toward 8-11Z. Again, confidence was not high enough to go with fog advisory. If sites to the northwest were actually foggier I would have been more likely to issue the fog advisory. && .SHORT TERM...(This evening through Saturday) Issued at 408 PM CST Thu Mar 7 2019 The main concern for the next 24-48 hours is the upcoming storm system approaching from the southwest. This is a complicated system for south central Nebraska and north central Kansas. A few things to note. Evolution: This storm system is expected to move across the Four Corners Region Friday afternoon/night with lee cyclogenesis deepening in southeast Colorado. Precipitation will develop Friday night after sunset with the low eventually tracking northeast across Kansas and eventually into Iowa. Warm air advection ahead of this system is the main concerning factor with how warm it will get. Temperatures are expected to remain steady or warm briefly overnight Friday into Saturday. A transition line will wobble right over the forecast area, which is what makes this a tricky event. After the system exits to the east, strong northwesterly winds will move in. Mixing with these winds could cause temperatures to rise during the day Saturday despite cold air advection. Something else to watch. Friday during the day/afternoon: Low clouds are expected to persist tonight into Friday with the potential for fog tonight. A concern looking at soundings across the area is the potential for freezing drizzle starting before 00z Saturday. The saturated depth with east winds eventually becoming southeast with warm air advection and some lift could cause freezing drizzle. Confidence was not high enough to put it in the forecast, but definitely wanted to mention it here. Precipitation Type: What a mess! To start, soundings look to be mainly drizzle or freezing drizzle prior to 6z Saturday, and forced drizzle as the precipitation type. After 6z, soundings saturate and rain, freezing rain, sleet or snow...a true wintry mix is the primary precipitation type. With warmer temps, but not quite warm enough to be all rain, this forecast has a bit more freezing rain and ice accumulation that the prior forecast. This could be overdone, but more on that below. Snow Amounts and Ice Amounts: Snow amounts have decreased quite a bit with the main precipitation type being freezing rain or sleet. This system is quick hitting and by the time the true cold air moves in, it will be exiting, so feel the better chance for snow remains north an inch or less in central Nebraska. Ice amounts with this forecast are up to 2 tenths, this is quite a bit higher and somewhat more scary than before...but am concerned this is way to high! I am not Confidence we will have THAT much freezing rain during the event. This whole event hinges on 2 degrees...and it`s the 2 degrees we are wavering around. Ice is a definite possibility, which will impact travel, but at this point am not expecting a lot of other impacts due to ice loading. Wind and Blowing Snow: The winds during the bulk of the precipitation will be light, but as the system exits Saturday morning, northwesterly winds will pick up with gusts up to 40 to 50 mph possible. These winds could cause additional blowing snow, even from old snow on the ground that could impact roadways. Something to watch for. Headlines: No headlines are being issued on this shift, but see a Winter Weather Advisory being issued tonight, and at the latest tomorrow due to the ice potential. The best chance for this is for all Nebraska counties, but cannot be ruled out for Kansas counties as well. While the temperature is a concern for later periods, feel that freezing drizzle and at least a glaze of ice from 00-6z Saturday is a good possibility and at a minimum a headline needed for that period. .LONG TERM...(Sunday through Thursday) Issued at 408 PM CST Thu Mar 7 2019 The main concern during this period is the next storm system looking to impact the area Monday night into Wednesday morning. This storm system is a bit more concerning regarding the amount of rain that may fall. While there are discrepancies among the guidance in the timing and location and specific details of the storm system as it impacts the Central Plains, there has been fairly good agreement for a few days that this storm system is going to bring rain to much of the area. This is concerning specifically because as of Thursday morning, the frost depth in Hastings is 25 inches and most locations across the area have between 5 and 15 inches of snow on the ground (not counting how the weekend system may impact this). With the ground frozen, the main concern will be flooding due to most if not all of the rain water being runoff. There is still a number of days until this impacts us, but it is definitely something to watch. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 558 PM CST Thu Mar 7 2019 Went pessimistic for visibility with expected light and variable to upslope flow. Ceilings should also tank as the night wears on. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ UPDATE...Heinlein SHORT TERM...Billings Wright LONG TERM...Billings Wright AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Houston/Galveston TX
944 PM CST Thu Mar 7 2019 .DISCUSSION... Ceilings lowering and the stronger winds starting relax so less mixing. Will be issuing a Dense Fog Advisory for the areas adjacent to Matagorda Bay through 9 am. Will probably need to expand it and plan to do so piecemeal given the remaining winds and webcams further up the coast still showing well over 6 miles...but eventually these too should come down. Updated the forecast for a little cooler temperatures early this morning 1-4 am in the northeast then will probably level out or start warming back up and to boost the cloud cover. Light drizzle will be possible throughout the night as LLJ starts to strengthen and gives the area a little stronger WAA pattern. Also looking at the soundings could see some streamer showers develop near Matagorda county toward sunrise and angle inland to the northeast. 45 && .PREV DISCUSSION... /ISSUED 614 PM CST Thu Mar 7 2019/ DISCUSSION [00Z TAF ISSUANCE]... Southerly wind flow will prevail during the TAF period, transporting low level moisture across the region. There was a break in the clouds today this afternoon and evening with the northern TAF sites reporting VFR ceilings, however, IFR cloud deck is expected to return tonight through Friday morning. Areas of fog are forecast to develop overnight through Friday morning. KGLS and KLBX may continue to see fog resulting in periods of IFR-LIFR through late Friday morning due to sea fog forming and expanding across the coastal areas. Warm air advection pattern will continue tonight and Friday with periods of showers affecting portions of the CWA. Also, local pressure gradient will tighten Friday resulting in an increase in wind speeds, with most sites possibly having winds at 10 to 15 kts with gusts up to 25 kts. PREV DISCUSSION... /ISSUED 358 PM CST Thu Mar 7 2019/ DISCUSSION... As of 3 PM, temperatures are in the mid 60s to low 70s with dewpoints in the mid 60s area wide. Water vapor imagery shows a pocket of drier air in the mid levels quickly eroding and moisture values are on the rise. Radar imagery this afternoon continues to show signs of drizzle and light rain mainly along and south of I-10. Short term guidance such as the TT WRF has done an excellent job with the placement of the precipitation today. Moving forward, the TT WRF, ARW, and HRRR all show coverage lessening during the overnight hours before picking back up around 10Z tomorrow and a similar pattern like today unfolds yet again for tomorrow. Rather zonal flow in the upper levels of the atmosphere can be anticipated for the remainder of the day and through Friday out ahead of a weak cold front that should approach the region on Saturday. As a result, SE TX will remain under cloudy skies with the chance for drizzle and showers through the remainder of the work week. Another weak disturbance and additional isentropic upglide will result in more showers tomorrow, with better chances for coverage along and south of I-10 beginning in the morning hours and spreading further inland tomorrow afternoon. With a warm air advection pattern in place, onshore flow will continue to advect in Gulf moisture, allowing precipitable water values (PWs) to rise from less than an inch area wide to 1.1 to 1.3 inches by Friday afternoon. Upper level flow becomes more divergent by Saturday morning, as the trough axis swings across the Plains, struggling to find a push to really dig southward. Forecast soundings show decent instability parameters with favorable unstable lapse rates and a cap at 800 mb that appears to erode by the afternoon hours (especially in the latest NAM12 solution) Saturday. The NAM12 is the also the fastest with its progression of this frontal boundary, pushing it just north of I-10 by 18Z Saturday. Interesting enough, the NAM12 is the driest model solution out of the global guidance, producing only a bit of precipitation along the boundary between 9-15Z in our far northern counties. Meanwhile, the GFS and ECMWF solutions are more similar lagging behind the NAM12 just slightly, and overall, producing more in the way of rainfall along the boundary itself. Also worth mentioning, the Storm Prediction Center has outlooked our NE zones under a marginal risk for severe storms with the primary hazard being damaging winds and possibly small hail. Additionally, the 850mb jet during does increase to between 50 to 60 kts Saturday morning, weakening behind the boundary by Saturday late afternoon. Therefore, at this the best coverage of showers and thunderstorms and risk of severe thunderstorms should remain NE of the forecast area. Our northeastern counties from Brazos to northern Harris into Liberty County and northeastward could see some strong storms and potentially isolate severe storms with this feature. Behind this frontal boundary, counties from Burleson to Houston may see short-lived partly cloudy skies as drier air attempts to build in early Sunday before mostly cloudy skies take back over. This boundary will wobble north and south through the remainder of the weekend and into the beginning of next week. This boundary will also act as a focusing mechanism for showers and thunderstorms for the beginning of the work week. Because this feature is never able to get the push it needs to clear the coast, wet and cloudy conditions linger through the weekend and much of early next week. The passage of our next cold front is forecast to push through the area sometime late Tuesday into Wednesday. Still plenty of uncertainty with the timing and strength of this system. Recent model runs have the GFS the fastest with the frontal passage, with the boundary oriented north-south and progressing west to east across SE TX (reaching our eastern counties by 12Z Wednesday), followed by the Canadian (reaching eastern counties 15Z Wednesday), and finally the ECMWF (18-00Z Wednesday). Hathaway MARINE... The return of mostly light/moderate onshore winds this afternoon/to- night will be favorable for the continued development of sea fog. A Marine Dense Fog Advisory has been issued for the bays and the near shore waters from the rest of this afternoon on through tomorrow at noon. Visibilities should be decreasing further this evening and be continued threat through the upcoming weekend (and then possibly in- to the start of next week). Models have been trending with the idea of stalling the next cold front (on Sat) over northern/central port- ions of SE TX...with a second stronger front progged for late Tues/ early Weds which would clear the fog out. In the meantime, this app- roaching front on Sat will help to tighten the gradient a bit tomor- row and we could see brief SCEC conditions over the offshore waters. Winds should be increasing once again late Mon/Tue/Tue night as the next next cold front approaches from the west. 41 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 64 78 67 76 55 / 30 20 50 50 0 Houston (IAH) 65 76 67 76 60 / 40 50 30 50 10 Galveston (GLS) 63 70 64 68 63 / 40 30 10 30 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Dense Fog Advisory until 9 AM CST Friday for the following zones: Coastal Jackson...Coastal Matagorda...Matagorda Islands. GM...Dense Fog Advisory until 9 AM CST Friday for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay. && $$ Discussion...45
Area Forecast Discussion
National Weather Service Lincoln IL
843 PM CST Thu Mar 7 2019 .UPDATE... Issued at 843 PM CST Thu Mar 7 2019 Updated the forecast for precipitation trends and to trim back a bit on snow/ice amounts overnight. The latest surface analysis indicated low pressure near the SE KS/NE OK border, with a trough extending northeast toward west central IL. The snow has tapered off in central Illinois, although a few bands of light snow remain in southeast IL. The water vapor satellite loops show a mid-upper level wave approaching central MO at 830 pm. This feature is expected to shift eastward and provide enough support for redevelopment of light snow in central IL between 10 pm and midnight - mainly south of Springfield-Mattoon line. Areas to the north should see a little light snow late tonight, but amounts will only be a few tenths of an inch. Forecast soundings from the HRRR and NAM continue to show that as the wave passes and the mid levels become dry, we will lose ice crystals aloft after 09z(3 am) in central IL. With plenty of moisture in the low levels, this should lead to light freezing rain/freezing drizzle. Not expecting this to happen in eastern/SE IL til just before daybreak. Overall, the amount of time favorable for freezing drizzle will be fairly limited, so icing should be minor - but still enough to create slippery conditions in spots for the AM commute. Thus, will keep the Winter Weather Advisory going overnight. && .SHORT TERM...(This evening through Friday) ISSUED AT 324 PM CST Thu Mar 7 2019 Warm advection snow band remains in place along and north of a Paris line this afternoon...while upstream radar imagery shows dry conditions across southern Iowa/northern Missouri. As has been advertised by the HRRR all day, the band will rapidly dissipate from west to east over the next 3-4 hours...leading to a lull in the precip early this evening. As low pressure currently over southeast Kansas slides eastward, wintry precip will re-develop later this evening into the overnight hours...with the precip most concentrated along/south of the I-70 corridor. With thermal profiles warming and a loss of ice crystals aloft, think light snow will mix with and/or change to freezing drizzle tonight. Storm total snow accumulations will generally range from 1 to 2 inches across the heart of the KILX CWA...with isolated amounts up to 3 inches. Ice accumulations will remain under one tenth of an inch, but will be significant enough to create slippery driving conditions. As a result, the Winter Weather Advisory will remain in effect until 10am Friday. After some lingering light snow/freezing drizzle Friday morning, dry weather will return by afternoon. Despite an end to the precip, boundary layer moisture trapped beneath a strengthening inversion will ensure an overcast day. Due to the clouds and snow cover, high temperatures will remain below guidance in the middle to upper 30s across all but the far SE where readings will top the 40-degree mark. .LONG TERM...(Friday night through Thursday) ISSUED AT 324 PM CST Thu Mar 7 2019 After a brief respite Friday afternoon/night, the next storm system will quickly progress into the region on Saturday. All model solutions track low pressure from eastern Colorado Friday evening to northern Michigan by Sunday morning...keeping central Illinois in the warm sector of the storm. Other than a narrow window of opportunity at the onset of the precip early Saturday morning, this appears to be an all rain system for central Illinois. In fact, as GFS MUCAPE values increase to 200-400J/kg, a few thunderstorms will be possible Saturday afternoon as high temperatures climb into the upper 40s and lower 50s. Rainfall totals will range from one half to one inch...enough to create ponding of water and full ditches...but likely not enough to warrant any widespread flooding threat. Once the low departs, cooler/drier weather will be on tap for Sunday and Monday...before the next system quickly tracks into the region within the progressive upper flow regime. Rain will develop Tuesday afternoon/evening...then will become more widespread on Wednesday as low pressure approaches from the west. High temperatures will be in the middle to upper 40s on Tuesday, then will soar well into the 50s and perhaps into the 60s by Wednesday as WAA increases markedly. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 558 PM CST Thu Mar 7 2019 A complex storm system will result in a variety of precipitation types and aviation conditions in central Illinois, particularly during the next 12-15 hours. MVFR to VFR conditions are being reported in many areas of central IL just before 00z. However, a pocket of IFR ceilings in west central IL extends from KSPI and westward. Expect this gradually shift east and impact KDEC from about 01-03z. The snow has also ended in this same area, and will gradually end from KPIA toward KCMI early this evening. Low pressure along the SE KS/NE OK border will shift eastward later this evening, and as it does it will result in the development of another round of light snow toward 04z. This will spread east and northward overnight, as indicated by numerous short range models. The HRRR has been consistent in depicting this the past several runs. It is also showing the loss of ice crystals in the lower-mid parts of the atmosphere, which will result in a mix and possible swich over to FZDZ after midnight from KSPI to KCMI. This will be followed by IFR ceilings in much of central IL early Friday morning due to the proximity of a surface trough and weak frontal boundary. Ceilings will gradually improve during the afternoon, but MVFR conditions will prevail. && .ILX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 AM CST Friday for ILZ027>031- 036>038-040>057-061>063. && $$ UPDATE...Miller SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Miller
National Weather Service Jackson KY
1059 PM EST Thu Mar 7 2019 .UPDATE... Issued at 1058 PM EST THU MAR 7 2019 Only some minor adjustments have been made to the overnight forecast. The first was to start the advisory in a tier of western counties from Rockcastle to Rowan where on average temperatures are colder and either ongoing bands of light snow were moving through near and north of I 64 or some steadier snow was expected to potentially begin before midnight as in the remainder of this western tier. As for trends in 0Z guidance, the bulk of the 0Z guidance supports the current forecast. Hourly grids have been updated based on recent observations. UPDATE Issued at 814 PM EST THU MAR 7 2019 Hourly grids have been updated based on recent updates and trends. One interesting trend has been the recent HRRR runs which have more QPF and snow from Estill County to Pike County than recent runs. This trend will continue to be monitored as the 0Z guidance rolls in for any possible changes. Overall, no significant changes have been made at this time. UPDATE Issued at 510 PM EST THU MAR 7 2019 Based on observations of temperature as well spotter reports there is a bit more snow mixing in for falling across the north and east compared to the previous forecast. With that in mind, added in a bit more of a mix of snow and flurries further south this evening with generally entirely snow or flurries through the evening for p type near and especially north of the Mtn Parkway. Otherwise, no changes were needed at this time. && .SHORT TERM...(This evening through Friday night) Issued at 355 PM EST THU MAR 7 2019 20z sfc analysis shows high pressure to the north of the area with a developing boundary lying across the CWA generally from northwest to southeast. Lowering cigs and virga continue along this with a potential for sprinkles or light rain on the warm side of the boundary and snow/flurries to the cold side. Temperatures range from the upper 30s north and east to the lower 40s in the southwest while dewpoints are mainly in the teens through eastern Kentucky. Winds, meanwhile, are generally light and variable. The models are in good agreement aloft through the short term portion of the forecast. They all depict slightly northwest of zonal flow over Kentucky into the evening with energy mainly staying north of the state. Later tonight into Friday morning, though, better height falls and more energy moves into and across the area from the west. Some upper level divergence will help out providing enhanced lift for the CWA tonight into Friday morning thanks to a quick jet streak passing by just south of Kentucky. Cyclonic mid level flow then moves off to the east later Friday with rebounding heights and some ridging for our state that night. Given the small model spread aloft will favor a blended solution with a near term nod to the higher resolution CAMs. Sensible weather will feature the lower levels moistening up this evening along a developing warm front bisecting the CWA. This will result in some light snow, mixed with light rain early, into the evening for the middle and northern parts of the CWA. Do not expect any significant snow to occur before midnight, but will have to watch this band and its potential to moisten up ahead of schedule. The NAM is more aggressive with the QPF through the night and would lead to more snow accumulation than currently forecast, but the GFS and ECMWF have much less. Have raised amounts with this forecast particularly north of the Mountain Parkway more in line with the CAMs guidance, and also extended the better snow amounts south a notch picking up an extra 4 counties for the advisory. The freezing rain threat seems to be even more diminished with enough turbulence and ice crystals expected to keep the cold column as mainly snow. Given the relatively mild sfc temperatures do expect the snow that falls to be wet and slushy for most of the area. Warming conditions then ensue later Friday changing the lingering snow to light rain from southwest to northeast. The remains of the pcpn slides off to the east with the sfc wave later Friday as temperatures remain above freezing through the night under cloudy conditions and a continued threat of light rain in the far south through Saturday morning. Used the CONSShort and ShortBlend guidance as the starting point for the grids with limited adjustments to temperatures given the small diurnal curve. Did adjust PoPs to go higher through the night and into Friday morning across the board shifting the higher QPF and snow a bit further south - in line with taking the advisory another row of counties south. Also started the advisory an hour sooner to allow for some uncertainty as the main wave moves into the area toward midnight. .LONG TERM...(Saturday through Thursday) Issued at 345 PM EST THU MAR 7 2019 A potent shortwave trough will rotate into the western great lakes on Saturday as an area of low pressure occludes over the northern great lakes. This system will send a warm front north into the region on Saturday with rain and perhaps a few thunderstorms developing with the isentropic ascent and low level jet. A line of showers and storms will then develop upstream along the cold front and advance east across the area during the mid to late evening hours. There is enough elevated instability to justify thunderstorms areawide. May need to watch for a strong wind threat with any more organized storms, but surface instability will be needed and right now, it looks fairly weak. The actual surface cold front may hang up to our west and may not make its way across the area Saturday night. Thus, milder weather will likely continue into Sunday and have stayed above guidance on temperatures for this period. A vort max rotating around the upper trough in the great lakes will eventually push the cold front through the area Sunday night allowing for cooler conditions to set in for the early portions of next week. High pressure will build into the area on Tuesday and should yield a fairly dry day with dewpoints well into the 20s, and relative humidities under 30 percent. Fortunately, dispersion and transport winds should be fairly low during this period to limit any fire danger. As high pressure shifts east on Wednesday, return flow will take hold sending our temperatures soaring by Wednesday. It does appear another system may take shape upstream by late Wednesday and could push into the area by Wednesday evening. However, these kinds of well developed systems tend to eject slower out of the plains than models anticipate, so its possible the dry weather will hold into Wednesday night. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 735 PM EST THU MAR 7 2019 VFR was generally in place across the region at issuance time with vis reduced at times in patchy snow. As the main mid level disturbance approaches from the west, we should a gradual lowering of ceilings into the MVFR range 8Z to 12Z. Some IFR CIGS and or VIS will occur by that time at least in heavier snow as well, mainly at or near JKL, SJS, and SYM. IFR or lower end of MVFR CIGS are expected to persist 12Z to 0Z as the low levels saturate, despite a VIS improvement as steadier precipitation departs. Winds will generally be light and variable, throughout the TAF period. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 AM EST Friday for KYZ044- 050>052-058>060-068-069. Winter Weather Advisory until 10 AM EST Friday for KYZ104- 106>112-114-119. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...KAS AVIATION...JP
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
620 PM CST Thu Mar 7 2019 .UPDATE... Issued at 620 PM CST Thu Mar 7 2019 Dense fog is underway from near Anselmo west through Tryon, southern Cherry county, Thedford, North Platte and areas in between. Dry air will move in later tonight and enhance the potential for dense fog. The HRRR and RAP models shows this feature and are the basis for a dense freezing fog advisory covering much of the Sandhills. && .SHORT TERM...(This evening through Saturday night) Issued at 330 PM CST Thu Mar 7 2019 For tonight: Patchy fog has persisted into the afternoon hours today. With sundown and SE winds expected tonight, the fog should re-develop once again across the western 2/3rds of the forecast area. This has support from the latest 12z NAM Bufkit sounding forecasts, as well as the SREF ensembles from earlier this morning. In addition, weak lift in the boundary layer, along with an easterly component in the winds, will lead to an increased threat for patchy freezing drizzle overnight. Have introduced both freezing fog and patchy freezing drizzle to the forecast. On Friday, a surface trough of low pressure, will deepen along the front ranges of eastern Colorado and sern Wyoming. Southerly winds will increase during the day Friday with the moist boundary layer remaining in place. Fog should persist into the morning hours with a temporary improvement in visibilities during the afternoon. By early Friday evening, the mid levels will begin to moisten as the upper level trough emerges from the Rockies. Before that mid level moisture arrives, some patchy freezing drizzle may be possible, especially in the southwest where meager boundary layer lift increases Friday afternoon. By Friday night, the emergence of the H5 trough, will initiate precipitation over NERN Colorado and western Kansas. This activity will lift quickly north northeast into the forecast area Friday evening. Forecast soundings support a wintry mix of precipitation for all of western and north central Nebraska with the exception of northwestern portions of the forecast area where cooler temps exist aloft. As for ice accumulations, am expecting these to be under a tenth of an inch as forecast soundings indicate only a very shallow layer of warm air more indicative of sleet or graupel vs. freezing rain. Across northern Nebraska, the threat for snow will increase Friday night into Saturday morning as the H5 trough lifts from western into eastern Nebraska. In these areas, the potential exists for 3 to 6 inches of snow late Friday night into Saturday morning. Even with snow totals trending down with this forecast package, went ahead and issued a winter storm watch to account for strong northerly wind potential Saturday afternoon into Saturday night. This will lead to blowing and drifting snow with the potential for near blizzard conditions over northern Nebraska. The fresh snow cover from last night`s system, won`t help matters either. As to the watch timing, carried it over into Sunday morning as the threat for blowing snow remains possible. .LONG TERM...(Sunday through Thursday) Issued at 330 PM CST Thu Mar 7 2019 Beginning Sunday morning, high pressure builds into the region bringing drier weather to north central Nebraska. Dry weather lasts through the beginning of Monday before the next chance of precipitation arrives Monday afternoon through the middle of next week. A developing low pressure system will track northeastward across the central Plains between Monday afternoon and Tuesday night. Inconsistency in the track of this system is quite high and therefore confidence is low regarding details of this system. Current model trends are indicating precipitation starting off as a rain/snow mix Monday afternoon before changing to all snow Monday night. Precipitation will then change over to all rain on Tuesday and eventually change back to all snow Tuesday night. Due to this changing from snow to rain to snow, total snow accumulations are uncertain as snow from Monday night may possibly melt during the day Tuesday as high temperatures rise to the mid 30s to low 40s. Will hold off on declaring any official snow totals for now as the forecast is still being refined. Precipitation is currently expected to continue into Wednesday before moving off the east by Wednesday afternoon/early evening. With colder temperatures on Wednesday (low to mid 30s), precipitation will likely remain mostly snow early Wednesday before briefly changing over to rain again in south central Nebraska. For Thursday, lingering snow showers/flurries are possible across the north. Otherwise, dry and cold conditions are expected across north central Nebraska. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 529 PM CST Thu Mar 7 2019 IFR/LIFR in fog and low or very low ceilings is expected to become fairly widespread tonight. Improvment to MVFR/IFR is expected 15z-18z Friday. There is a chance that the IFR/LIFR will last into Friday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... Freezing Fog Advisory until 10 AM CST /9 AM MST/ Friday for NEZ005-023>026-035>038-059-094. Winter Storm Watch from Friday evening through Sunday morning for NEZ004>010-023>029-094. && $$ UPDATE...CDC SHORT TERM...Buttler LONG TERM...Kulik AVIATION...CDC
Area Forecast Discussion
National Weather Service New Orleans LA
838 PM CST Thu Mar 7 2019 .SOUNDING DISCUSSION... This evening`s balloon launch was successful with no problems encountered. Observing the state of the atmosphere this evening and comparing to the previous 12 hours illustrates some interesting changes. A surface high pressure area that helped deliver much colder air to the area has drifted slowly to the east across New England and the Ohio Valley. With the northern Gulf coast on the southwestern periphery of the anticyclonic surface flow around the high pressure center, better deep moisture return at the surface to low-levels is evident in the thermal profile. This is also supported by an increase in low-level winds as hodographs depict a slightly stronger warm air advection pattern in place. However, much drier air resides in the mid-levels, indicating a sinking, stable airmass in this layer. Meanwhile, the upper-levels continue moist from around 250mb to the tropopause as a relatively active quasi-zonal upper-air flow advects moisture in from the Pacific in the form of cirrus clouds across the area. This upper-level feed of Pacific moisture is also very evident on GOES 16/17 UL Water Vapor IR Band satellite imagery. So for tonight, with better deep-layer low-level moisture return in place, as well as a relatively thick cirrus canopy across the area, overnight lows will range 15 to 25 degrees warmer than last night. Any rain would be better associated with the deeper moisture flux return to our west, collocated with a much stronger warm air advection. Spotty drizzle cannot be ruled out, especially near or west of the Mississippi River but should remain dry through daybreak. KLG && .PREV DISCUSSION... /issued 351 PM CST Thu Mar 7 2019/ .SHORT TERM... The recent sunny and cool weather period is gradually coming to an end as transitioning into a wet pattern takes place. Upper level trough and surface ridge are both sliding east, allowing for moisture levels to begin to rise throughout the column. Mid level clouds are already rolling in and higher dewpoints should be doing the same this evening and tonight. Regional radars shows light showers tracking northeast across southeast TX and SW Louisiana. HRRR and medium range models do indicate a little of that activity spreading into northwestern zones during the overnight period. Therefore, have added slight chance of rain in those parishes and counties from BTR and northwestward. Impacts should be minimal. Friday should be similar to tonight with moisture levels increasing as southerly flow strengthens. Dewpoints will continue slowly rising and isolated to scattered light showers will be developing with coverage highest north of I-12. Again, qpf totals should be on the low side, a tenth of an inch or less. A stronger onshore push Saturday will bring dewpoints into the mid 60s. Increased 500mb heights will allow for temperatures to moderate well into the 70s. This combo will first, bring the potential for thunderstorms. Afternoon CAPE values are upwards of 1000j/kg but that doesn`t tell the whole story. The sounding profiles show that the lapse rates below 15kft are generally moist adiabatic with sharp cooling above that layer. This type of profile, even with bulk shear values of 50-60kts isn`t particularly conducive for severe storms. Thus, the SPC D3 marginal severe risk seems quite appropriate. Sunday and possibly Monday, however, look a bit more conducive for severe potential. The main difference is we`ll have a stalled frontal boundary in place for a focal point and instability is much deeper, starting at near 850mb instead of 650mb. The wind profile doesn`t provide nearly as much shear, but wbz down to 10kft is plenty low enough for hail. It may be a marginal severe risk day as well, but feeling more confident for Sunday than Saturday based on current model solutions. .LONG TERM... Tuesday progged to be a transitional day. The frontal boundary that was in place will dissipate while upper level ridge passes across the region. Temps should respond to this by moderating quite a bit. Have increased highs by a few degrees from the previous forecast, staying close to MEX as blends typically miss days like this. Strong building ridge this time of year is typically indicative of a strong trough to the west and that appears to be the case this time as well. Models show an upper trough dropping out of the Rockies Tuesday and occluding as it tracks across the Central Plains Wednesday/Thursday. This will bring the tail end of a cold front into the CWA Wednesday. From there, models diverge quite a bit. The GFS suggests it will stall near the area and remain in place until the next trough pushes it out. The ECMWF on the other hand stalls it south of the region before the next trough moves it along. Uncertainty remains high that far out with either wet or dry scenarios possible. MEFFER .AVIATION... Mainly VFR conditions with good VSBY and mid level/VFR category CIGS are expected at most locations through Friday. The exception is at KBTR, KHDC and KMCB where MVFR CIGS are forecast to develop late tonight/early Friday morning after 10-11z. 22/TD .MARINE... High pressure currently over the eastern United States will continue to move eastward tonight as low pressure develops over the southern Plains. This will result in southeast to south winds mostly in 10 to 15 knots range tonight with highest winds over western coastal waters (offshore from Terrebonne Parish). These onshore winds mostly in 10 to 15 knots range are expected to continue through Saturday night. A strong low pressure system moving out of the central Plains into the western Great Lakes region will have an associated cold front approaching the coast from the northwest Saturday night into Sunday. This will bring increasing shower/storm chances. The front will likely stall near the coast early next week. 22/TD .DECISION SUPPORT... DSS code: Blue. Deployed: None. Activation: None. Activities: River Flood Warnings Monitoring potential for severe weather this weekend && .PRELIMINARY POINT TEMPS/POPS... MCB 55 72 62 77 / 20 30 10 40 BTR 57 75 63 80 / 20 30 10 30 ASD 57 74 62 79 / 0 10 0 20 MSY 59 75 64 79 / 0 10 0 20 GPT 57 71 63 75 / 0 10 0 20 PQL 55 72 63 78 / 0 0 0 30 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Morristown TN
943 PM EST Thu Mar 7 2019 .DISCUSSION...Forecast mostly on track with a few minor adjustments made. We`ve had light radar returns over the area for the past several hours but still nothing reaching the ground as the airmass in the lowest levels is still very dry. Light precip in the form of rain/snow will begin first up across southwest Virginia and extreme northeast TN. This is because the airmass is a bit more saturated up that way due to the colder temperatures. Elsewhere, dewpoints still in the upper teens to lower 20s with temps in the low to mid 40s so it will be a while before precip reaches the ground. The current special weather statement still looks good as light snow is still expected later tonight across some of our northern areas, once the airmass further moistens. Impacts still expected to be minimal due to the short window of time that the snowfall is expected to occur in, along with the light QPF. Other updates were to tweak hourly temps and dewpoints. Also made some minor changes to POPs to match up with latest HRRR and RUC which show the better chances of precip not occurring until between 09z and 12z. Will send out new zones. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 42 54 49 64 / 40 90 80 80 Knoxville McGhee Tyson Airport, TN 38 48 44 61 / 30 90 70 70 Oak Ridge, TN 36 48 44 62 / 40 90 60 80 Tri Cities Airport, TN 33 44 39 59 / 40 80 60 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ SR
Area Forecast Discussion
National Weather Service Pueblo CO
816 PM MST Thu Mar 7 2019 .UPDATE... Issued at 801 PM MST Thu Mar 7 2019 The Winter Storm Warning for the E Sawatch and W Mosquito Mtns and Leadville area was allowed to expire at 8 PM as snow has largely come to an end in those areas. GOES water vapor imagery indicates the shortwave trough has moved east of the area and shortwave ridging has taken over, leading to mainly dry conditions across the forecast area. Weak energy embedded in the southwest flow may bring periodic light snow showers to the Continental Divide later this evening through tomorrow morning. Snow is still expected to pick up again tomorrow afternoon as another shortwave trough, currently off the California coast, advances east through the region. Therefore, the Winter Weather Advisory for the Continental Divide remains in effect from Noon tomorrow through 5 AM Saturday. ~Line UPDATE Issued at 553 PM MST Thu Mar 7 2019 Winter Weather Advisory across the eastern San Juan and La Garita Mountains, and parts of Chaffee county, was allowed to expire at 5 PM this evening as snow has largely come to an end across those areas. The Winter Storm Warning for the E Sawatch, W Mosquitos, and Leadville area looks good to expire at 8 PM this evening as snowfall and gusty winds continue to decrease in coverage and intensity. ~Line && .SHORT TERM...(This evening through Friday) Issued at 239 PM MST Thu Mar 7 2019 ...Parade of weather systems to continue as heavy snow returns to the Continental Divide Friday... Trailing upper energy and favorable moist orographic flow keeping some banded snow showers going over the Central Mountains, and will retain highlights into the evening as models suggest some accumulations (1-3 inches, mainly from Monarch Pass northward) still possible until at least sunset. Snow should diminish overnight, but may not end completely as snow showers and flurries linger into Fri morning. Farther east, still getting some gusts around 50 knots near Trinidad, though remainder of the area has seen winds settle back into the 35-45 kt range. Waited most of the day for winds around Pueblo and Colorado Springs, with weak convection/virga finally boosting mixing and bringing gusty/warm conditions to the area after 2 pm. Overnight, winds should decrease all areas, though upper jet overhead will keep conditions above timberline brisk with areas of blowing snow. HRRR now suggests low clouds and fog may redevelop over the lower Arkansas Valley as easterly wind redevelops, with stratus making it all the way back to Pueblo/Colorado Springs after midnight. Confidence is low given poor model performance the past 24 hrs, but will include some fog from La Junta eastward as westerly flow will likely not reach the KS border before reversing after sunset. On Friday, next wave reaches the srn Great Basin by 12z, then races quickly into wrn CO by late afternoon. Snow will increase along the Continental Divide by afternoon, and some bursts of heavy snow will be likely by 00z as dynamic lift increases. Will hoist a new advisory for most zones along the Divide beginning around noon, as conditions will worsen late in the day. Interior valleys and eastern mountains will see snow showers by afternoon, though accums will be light. On the plains, surface low spins up in its preferred location south of La Junta, bringing gusty west winds and warm temps to the I-25 corridor and much of the plains, though east wind in the lower Ark Valley will keep locations near the KS border on the cool side of blended guidance once again. .LONG TERM...(Friday night through Thursday) Issued at 239 PM MST Thu Mar 7 2019 ...Active weather to continue into next week... Models and ensembles continue to have close agreement through the extended period with low ensemble spreads. This leads to high forecast confidence through the extended period with an incoming storm system. Friday night...a fast moving upper level shortwave trough will be moving across the area Friday night. Snow will be ongoing along the Continental Divide during the evening hours which could be heavy. Locations over the Central Mountains will see the highest amounts before dissipating late. Across the Plains, models are in good agreement with a band of rain and snow lifting northeast into Kansas overnight. This band should clear into Kansas by Saturday morning. Any snow accumulations will be minor and remain confined to grassy surfaces. Saturday and Sunday...strong zonal flow will encompass the region on Saturday with mixing allowing for strong winds at the surface. This will help temperatures to rise into the 50s to perhaps a few low 60s across the Plains. Near critical fire weather conditions will exist, mainly over the I-25 corridor. Winds will definitely be there, with gusts in excess of 30 mph expected, but humidity values are expected to remain just above 15 percent. Over the mountains, periods of light snow will continue over the Central Mountains where an inch or two of accumulation are expected. By Sunday, the upper level flow will shift southwesterly as the next storm system approaches. Snow will continue to be light over the Continental Divide throughout the day. Winds are also expected subside by Sunday morning with weak high pressure aloft moving across the area. Temperatures will be slightly cooler behind the departing system with generally 40s across the lower elevations. Monday into Thursday...a major storm system is forecast to move across Colorado beginning Monday and persisting into Wednesday. Snow will increase by Monday morning over the mountains, especially the San Juan and Southern Sangre ranges. As the upper system slowly moves across the Desert Southwest, expect rain and snow to expand across the region. The mountains will likely see several inches, if not feet of snowfall through Wednesday. As for the Plains, models in good agreement with a heavy band of rain moving up from the south with a very good moisture tap. Model projections are printing out around 1 to 2 inches of rainfall as the upper system moves into New Mexico Monday night into Tuesday. Temperatures at this time look to remain above freezing, with all precipitation looking like rain. As the upper system closes off in western Kansas, and lifts into Nebraska, colder air will move into the Plains behind a cold front. Models are mixed with rain and snow across the Plains behind the cold front and how long they want to hold on to it. Minor accumulations may be possible in the wrap around precipitation band. By Wednesday afternoon and Thursday, broad northwesterly flow will encompass the area with more energy dropping across the area. This will likely keep snow going over the mountains, while areas on the Plains will depend on upslope flow. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 239 PM MST Thu Mar 7 2019 At KALS, VFR conditions expected overnight and through the day on Friday. Very slight chance of a shower near the mts until 02z, won`t include in the taf at this point. Strong southwest winds this afternoon will drop back into the 10-20 kt range this evening, before increasing quickly again Fri morning, with gusts to 40 kts after 18z. At KCOS, virga/isolated -shra have increased the winds across the terminal this afternoon, with some gusts to 30 kts possible into the evening. Winds diminish this evening, then turn easterly 03z-05z, with a potential return of IFR cigs/vis for a period 08z-16z, before clearing and VFR by 18z as gusty S-SW winds return. At KPUB, gusty west winds will persist into the evening, then turn easterly 03z-05z. Expect a return of stratus and fog after 06z, with a period of IFR cigs/vis 08z-17z. Clearing with VFR conditions expected after 18z, with gusty S-Sw winds returning. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from noon Friday to 5 AM MST Saturday for COZ058>061-066-068. && $$ UPDATE...LINE SHORT TERM...PETERSEN LONG TERM...MOZLEY AVIATION...PETERSEN