Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/12/19

National Weather Service Kansas City/Pleasant Hill MO
1049 PM CDT Thu Apr 11 2019 .Discussion... Issued at 329 PM CDT THU APR 11 2019 Strong W/SW winds continue to blow through the area this afternoon, bringing occasional wind gusts approaching 40 to 50 mph. The deeper mixing associated with the clearing in the clouds allowed for a better momentum transfer, thus getting some of the 40 to 50 mph winds to the surface this afternoon. As the sun goes down tonight expect some decoupling of the surface conditions from the low level winds just off the surface. That being said, RAP forecast soundings from across the region for tonight indicate only a weak temperature inversion just off the surface which may allow for continued mixing through the overnight hours. While gusty winds may not be continuous overnight there is enough of a chance for mixing to maintain wind gusts in the 20 to 30 mph range overnight. The continued cold air advection through the evening and overnight may get temperatures down into the lower 30s for Friday morning. Wind chills will likely drop into the 20s for Friday morning and temperatures at or below freezing may provide some concern for sensitive outdoor vegetation. Confidence in temperatures dropping below 32 degrees is a low to medium, with the lone concern being the stronger winds overnight perhaps keeping the lower atmosphere mixed well enough to keep temperatures more in the middle 30s as opposed to lower 30s. Friday will see winds continue out of the W/SW through the day, with perhaps a slight ramp-up as the lower atmosphere gets mixy again. Saturday and Sunday will see the active pattern continue for the region as another very large trough is poised to dig into the Southern Plains and eventually eject northeastward through the area. Moisture will push in from the south through the day on Saturday, and eventually by Saturday evening and Saturday night we should see some rain falling across the region. Saturday itself should be just fine from a precipitation standpoint, meaning we are expecting the bulk of the day on Saturday to be dry. By Saturday night temperatures will fall as the surface cyclone treks south of the I-70 corridor. This track of the low level cyclone will funnel cold air into the area concurrent with the ongoing precipitation. This system will carry characteristics that resemble very closely a strong/significant winter storm, especially regarding the high moisture content deformation band north and west of the low level cyclone. However in this case the system will lack the really cold air necessary to convert all of that moisture into accumulating snow. H85 temperatures will be well below 0C, so snow production is likely with this system, mainly through the early portions of Sunday morning. The big question is how cold the surface conditions will get. Right now we are expecting surface low temperatures to remain in the lower to middle 30s for Sunday morning, which will be adequately cold enough for the snow to reach the surface. Currently we do anticipate at least some periods of light rain/snow mix across a large portion of the area Sunday morning. Accumulation at this point seems unlikely considering ground temperatures will be much warmer than freezing, however should low temps on Sunday morning drop to around freezing it`s plausible that we could see some minor accumulations of snow on elevated surfaces like trees and grassy surfaces. Expect this system to move out of the area by Sunday night, leaving behind roughly 1/2" to 1" of precipitation in its wake. The next system moves in midweek, and has a very similar appearance to it, namely a large, potent mid level low, with an uncertain low level cyclone track. A more southerly track of the low level cyclone will funnel the colder air southward into the area, and the system will behave similarly to the weekend system with several tenths of an inch of cold rain and an outside chance at some rain/snow mix. The GFS solution would keep the low level cyclone a little further north, which would put the area into a warm sector, with moisture to fuel some instability and perhaps bring a chance at some thunderstorms. Given the large spread in operational models will hold off on any high, or even medium confidence with respect to the mid week system. && .Aviation...(For the 06Z TAFS through 06Z Friday Night) Issued at 1049 PM CDT THU APR 11 2019 VFR conditions will prevail through the forecast period. Gusty west-southwest winds of up to 25 kts will prevail overnight before slightly veering to the west after 14z. Winds will remain gusty all day with gusts of 30 kts possible until early evening when the pressure gradient relaxes. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Freeze Warning until 9 AM CDT Friday for KSZ025-057-060-102>105. MO...Freeze Warning until 9 AM CDT Friday for MOZ020>022-028>030-037- 043. && $$ Discussion...Leighton Aviation...32
Area Forecast Discussion
National Weather Service Hastings NE
649 PM CDT Thu Apr 11 2019 .SHORT TERM...(This evening through Friday) Issued at 336 PM CDT Thu Apr 11 2019 Aloft: WV imagery/RAP tropopause analyses and aircraft obs indicated moderately-amplified flow...with a longwave trof was over the Wrn/Cntrl USA...and a ridge over the E Pac. The low that affected the CWA last night and today was along the SD-NEB border near YKN. This low will slowly lift into MN by 12Z/Fri and head to near DLH by 00Z/Sat. In its wake...cyclonic W flow will remain over NEB/KS. Meanwhile...a shrtwv trof will dive down the back side of longwave trof and into the Desert SW. Surface: Filling low pres was over NW IA. This low will cont to fill as it occludes further tonight on its way into Srn MN. This low will weaken into a trof over MN/WI tomorrow. The pres grad here will gradually relax with weak high pres moving in late in the day. Post Mortem: This system definitely fell short of expectations... good from an impacts standpoint...but not from a fcst viewpoint. The performance of the EC was espcly disappointing...track of sfc low...QPF etc. Its low was too deep and too far W. One aspect that over-performed was the amt of hail that occurred with last night`s tstms. See LSR`s for hail/snow. The hail 4" deep btwn Kearney-Gibbon was espcly impressive. After viewing snowplow cams...trimmed most of the counties from the Winter Wx Advy. Left the advy just for where winds were gusting to 45 mph and producing some BLSN. Rest of this afternoon: M/cldy and windy. There are some pockets of -SN lingering here and there. Clds are breaking up over the SW 1/3 of the CWA from Cambridge-Plainville-Osborne. NW winds will cont gusting 30-40 mph with and ocnl G45. Tonight: M/cldy N of I-80 but decreasing clds S of I-80. There is quite a difference btwn the 06Z/12Z NAM vs the 06Z/12Z GFS and RAP regarding the extend of low clds vs clearing. The GFS and RAP are more pessimistic while the NAM runs are more aggressive with the dcrsg clds. Still windy. NW winds 20-30G45. Lows are a blend of the NBM with a little nudge up using the blend of mdl 2m temps. Fri: P-M/cldy along and N of Hwy 6. M/sunny S of Hwy 6. The cold thermal trof will be over the CWA and fcst sndgs show quite a bit of deep CU/SC will form with a sliver of CAPE. These clds will be within the DGZ so expect sct snow shwrs in the morning...changing to rain shwrs in the afternoon where temps will be just warm enough. Still windy as NW winds will be 15-25G35. Temps much cooler than normal with highs in the 30s/40s...coldest along and N of the Platte Rvr. .LONG TERM...(Friday night through Thursday) Issued at 336 PM CDT Thu Apr 11 2019 Aloft: The last 2 runs of the EC/GEM/GFS/GFS-FV3/UKMET mdls cont to fcst the longwave trof to remain over the W thru next Wed. This remains consistent with the 00Z EC ensemble mean. Two more substantial shrtwv trofs will rotate thru the larger trof. The 1st thru the Srn Plns Sat-Sat night and the 2nd next Wed. As this latter trof moves E of the Plns...this will initiate a pattern chg a Wrn rdg/Ern trof and NW flow here. As for the shorter wavelengths...troffiness will remain over the Cntrl Plns Sat...but a shrtwv rdg will arrive Sun with the flow temporarily deamplifying. Heights will then begin falling again Mon- Tue as the trof deepens over the W. That flow will re- amplify. There is considerable uncertainty in what the trof will look like when it ejects into the Plns Tue night into Wed. The 06Z/12Z GFS-FV3 and 00Z/12Z GEM runs are the strongest. NW flow will develop here next Thu as that sys moves into the Ern USA. Surface: Anticyclogenesis will occur over the Plns Fri night-Sat as the high overhead strengthens. This high will weaken Sun. A lee low will form over CO Mon ahead of a cool front fcst to be making its way thru the Wrn USA. Return flow will strengthen with a substantial warm-up...but it will be short-lived as the cool front will cross NEB/KS Mon night. Another low will form on the tail end of that front Tue over the TX panhandle. As that low lifts up the front... that could spread some rain into the CWA Tue night into Wed. The CWA will remain in the cool sector Thu behind a deepening low well to the E. Temps: Much cooler than normal Sat-Sun. A big warm-up Mon- a little warmer than normal. Then dropping back close to or a little cooler than normal next Wed-Thu. Precip: Currently the fcst has nothing Mon night...but there could be sprinkles N of I-80. Tue night into Wed there is potential for some substantial stratiform rain...mainly S of Hwy 6...but gvn the uncertainty aloft...wouldn`t bet on it just yet. For now left thunder out of the fcst. While the 12Z GFS is close to its ensemble mean with the position of the sfc is the further N of the last 2 runs of all the global mdls...suggesting that it`s too far N with its instability. Spaghetti plots 12Z/Wed show the GFS low near SLN while all other mdls are over OK or the TX panhandle. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 633 PM CDT Thu Apr 11 2019 Lower clouds will break up overnight. During the day tomorrow, there will be some cold air cumulus that form. Northwest winds will remain breezy through the period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Winter Weather Advisory until 7 PM CDT this evening for NEZ039- 040-046-060-061. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...JCB
National Weather Service Wilmington OH
1009 PM EDT Thu Apr 11 2019 .SYNOPSIS... Dry weather and warm temperatures associated with a strong southerly flow will persist through early tonight, until a vigorous cold front brings showers and a few thunderstorms late tonight through early Friday. High pressure and dry weather will arrive by Friday evening, with dry conditions expected to last through the daytime on Saturday. Showers and a few thunderstorms are forecast for Saturday night and Sunday in the moist circulation around deep low pressure. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... A surface cold front is now moving through Illinois, roughly crossing the central part of the state as of 02Z. Meanwhile, a warm front remains right at the far northern end of the ILN forecast area, expected to move very little through the overnight hours. The main story is going to be the progression of the cold front, which is now forecast to cross the forecast area between about 10Z and 16Z. Multiple broken bands of showers and embedded thunderstorms are expected to accompany the frontal passage. Southerly flow in the warm sector is fairly strong, with the ILN sounding sampling 34 knots at 850mb, and indications from models that 850mb winds may increase to around 60 knots just before the cold front passes. With that said, there is little expectation of any surface-based instability, so convective wind gusts are not really expected to be a concern. With that said, there may be some warm advection gusts ahead of the front, and some gusts just behind the front associated with the cold advection / pressure rises on its back side. As of now, it looks like this should all remain in the 25-35 knot range. As mentioned below, additional wind gusts are possible Friday afternoon, roughly to the same magnitude. T/Td projections were tightened up for the overnight hours, using current obs and HRRR data to get things as accurate as possible. Previous discussion > Area remains under a strong southerly flow in the warm sector ahead of a vigorous cold front that is near the Mississippi River. Dry weather will continue early tonight, until later in the overnight hours when the cold front travels to Indiana. Rapidly increasing moisture and lift near the boundary will cause showers and possibly thunderstorms to develop after midnight beginning in western counties. Severe storms are not likely due to weak instability at an unfavorable time of day for convection. However, a potent low level jet will probably mix down, resulting in winds gusts above 30 knots with some of the showers. Keeping mention of 40 mph gusts in HWO for this expected sub advisory event. Temperatures in the warm and well mixed airmass will stay far above normal with readings in the mid 50s to mid 60s by 6 am. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... We will see showers and a few thunderstorms spreading east across the area Friday morning, accompanied by 30+ knot wind gusts. A rather quick drying trend should then be observed Friday afternoon and evening as the cold front works east, to be replaced by an elongated area of high pressure forming under a southwest flow aloft. Subsiding winds and mainly clear skies are forecast for Friday night, when lows are expected to range from the lower 40s northwest up to the upper 40s southeast. && .LONG TERM /SATURDAY THROUGH THURSDAY/... On Saturday, a west to east oriented surface high pressure ridge will be located over the region. Skies will start out mostly sunny with some increase in clouds from the southwest later in the day ahead of the next weather system. Highs will range from the lower 60s northwest to the lower 70s southeast. A dynamic system (mid level trough) is still forecast to eject out of the southwest U.S. into the southern Plains, then into the Great Lakes and Ohio Valley Saturday night into Sunday night. Associated surface low is expected to track through our western CWFA late Sunday into Sunday evening. Wet weather will return with PoPs ramping up to categorical values by Sunday. There is a risk of some thunderstorms region wide, especially Sunday afternoon and evening in proximity with the surface low (highest instability) and northward moving warm front. Shear will be substantial, so the prospects of severe weather will be based on the amount of instability that can be realized via advective processes and diurnal heating. At this point, it appears to be marginal. Also, for now, SPC does not have our region outlooked (focused more to the south), but this will have to be monitored should our area be upgrade to at least a marginal risk. Some of the rain may be moderate to locally heavy given higher pwats and good influx of moisture out of the Gulf of Mexico. Generally, 1 to 2 inches of rain are expected. Temperatures on Sunday will vary based on the low track, so we will continue to fine tune these values as models come into better agreement. After lows ranging from the lower 40s north to the lower 50s south, highs will range from the upper 50s northwest to the lower 70s southeast. Pcpn will shift to the east Sunday night into Monday as the surface low and mid level trough move east as well. We should see some partial clearing across the southwest CWFA by Monday afternoon. After lows in the upper 30s to the mid 40s, highs on Monday will range from the upper 40s north to the mid 50s south, cooler than normal for mid April. High pressure looks to build back into the region Monday night into Tuesday, while a warm front develops across the southern Great Lakes. After cool lows in the upper 30s to the lower 40s, Highs will rebound into the mid 60s north to the lower 70s south. The next large scale weather system will be making in roads into the region Wednesday into Thursday. Timing and strength issues exist at this juncture so a broad brush approach was used for the forecast. Low chances of rain return on Wednesday into Wednesday night, with likely PoPs introduced back into the forecast on Thursday. High temperatures will be a little bit above seasonal normals. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... While VFR conditions are expected through the TAF period, there are other concerns to discuss, primarily with regards to winds. Gusty southerly winds this afternoon have started to diminish somewhat, and will probably remain at a relative minimum through around 05Z. After that, wind speeds will increase, with gusts pushing into the 20-25 knot range through the rest of the overnight. A few gusts to around 30 knots will also be possible later in the overnight, just ahead of the approaching cold front. When this front arrives, a period of showers is expected. Though generally VFR, there is a slight chance of a few pockets of briefly MVFR visibilities or ceilings with the rain. There is also a small chance for thunder, but too low to include in the TAFs. Behind the front and the main area of rain, winds will shift to the southwest. These southwesterly winds will again increase on Friday afternoon, with gusts to around 30 knots possible. OUTLOOK...MVFR conditions and thunderstorms are possible on Sunday and Sunday night. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio/Hatzos SHORT TERM...Coniglio LONG TERM...Hickman AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Key West FL
1037 PM EDT Thu Apr 11 2019 .CURRENTLY...(Tonight) A dry air mass is in place over the Florida Keys this evening. The 00z KEY sounding supports this statement, with a PW value of only 0.90" and sharp drying on the sounding beginning as low as 4100 feet. GOES-16 low-level water vapor imagery (Channel 10) shows a large mass of very dry air encompassing the western Caribbean, the Yucatan, Bay of Campeche, and the Straits of Florida. Not surprisingly, skies have been clear over the Florida Keys this evening. The 00z KEY sounding also showed a somewhat shallow layer of southwest winds from 3,000 to 8,000 feet. The remnant low tops of afternoon Cuban convection are riding north in this layer over the Straits and may add a little extra depth to the shallow surface-based moisture overnight. Several models --- which include the GFS, ECMWF, and the HRRR --- develop a few showers over the Straits overnight which then drift north to the Lower and Middle Keys around sunrise. The 00z NAM skips the overnight development and fits best with the conceptual models associated with a dry air mass. If showers start to develop over the Straits, would need to update the forecast to add isolated showers late tonight for the Lower and Middle Keys. .SHORT TERM...(Friday through Sunday) The shallow surface-based moist layer will gradually deepen over the course of Friday through Sunday, thanks to deep southeast flow bringing moisture in from further east in the Caribbean. An increase to fresh east-southeast breezes on Saturday night will also favor more mesoscale boundaries along the leading edge of wind surges. So the increased moisture and strong E-SE flow in the boundary layer will help PoPs to gradually creep up from 10s to 20s during this period. Inhibiting factor will be a north-south oriented upper ridge axis that will drift from over the Keys on Friday to near the Bahamas on Sunday. && .LONG TERM...(Sunday night through Thursday) From Previous Discussion: Surface ridging will remain north thru northeast of the Florida Keys thru the period. Temperatures will continue typically warm or slightly above normal, mid to upper 80s and mid to upper 70s respectively. Forecast soundings continue to show enough moisture quantifying a slight chance for showers thru the period. && .MARINE... A flat surface ridge axis from the Atlantic will nose into Georgia on Friday and Saturday. East-southeast breezes will freshen on Saturday, as air gets drawn into a strong low center moving northeast through Arkansas. Breezes over the Keys waters will peak on Saturday night, with fresh and possibly strong east- southeast wind expected. This will eventually necessitate at least SCEC headlines, but SCA conditions are possible too. Winds will start to ease on Sunday, as the low center moves northeast far away from the Keys. A trailing cold front will approach the Keys on Monday but will dissipate before arriving here. A surface high center will fill in across the southeast U.S. on Tuesday, supporting gentle to moderate easterly breezes over the waters. && .AVIATION... VFR conditions at EYW and MTH terminals for the next 24 hours. E-SE breezes will prevail. The leftover clouds from afternoon convection over Cuba is drifting north across the Straits right now. This could bring a few clouds across the islands in the 040-060 layer through sunrise. On Friday, FEW-SCT coverage of fair weather cumulus will drift in from the Straits with bases in the 025-035 range. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Haner Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1020 PM EDT Thu Apr 11 2019 .SYNOPSIS... High pressure will remain in control as it gradually slides off the Mid-Atlantic coast through Friday. A cold front will approach the area late Friday into Saturday and likely stall just to the west. A strong low pressure system will impact the area late this weekend and early next week. High pressure will build in Tuesday and Wednesday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 1020 PM Thursday...No major changes to the forecast with widespread cirrus continue to move in from the west and northwest at late evening. Latest high-resolution models show that the strong surface ridge will gradually shift offshore tonight and deeper moisture being drawn north into our region toward morning. Gradient will tighten overnight between the retreating surface high and oncoming cold front over the Tennessee Valley. These gusty SE winds will hold minimum temperatures up overnight with lows mainly mid 50s inland to lower 60s coast. Minimal changes needed to the current forecast at this time. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... As of 2 PM Thu...Deep low pressure system currently over the Mid-West will continue to lift NNE into the Upper Mid-West and Canada, with attendant cold front approaching the area from the west. Deepest moisture and dynamics will remain W/NW of the area, but should be enough to support widely scattered showers maybe an isolated tstm late morning and into the evening hours. Best chances still look like the inland areas, mainly west of Hwy 17. Low level thickness values, SE winds and increasing clouds support highs in the low to mid 70s along the coast and into the upper 70s inland. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... As of 330 PM Thursday... Unsettled weather is forecasted for this weekend, then high pressure will build across the area leading to dry and mild conditions. Friday night and Saturday... A weak cold front will sag across our state and stall as the area will be in a deep southerly moist flow which will allow for sfc convergence near the boundary with widely scattered showers and possible thunderstorms Friday night, especially Saturday. With the front near the area I didn`t want to yank the thunder chances out of the forecast as the latest models are showing CAPE values near 1200 J/KG and lift index around -5, but there will be a good amount of cloud cover on Saturday which can limit the instability. Expect highs in the mid/upper 70s inland and near 70 degree along the OBX. Sunday... The front mentioned above will be north of our area and we will fully be into the warm sector with highs into the 80s away from the water. We continued with low chances for showers or storms during the day but nothing organized is expected with a decent cap in the mid levels and no large scale triggers. Our reliance will be on smaller mesoscale features such as the sea breeze which should get a good push inland with southerly winds expected. A much larger chance for widespread showers and embedded thunder will come Sunday night as a cold front moves through the area. Wind profiles would support some stronger storms but the timing of the front and lack of instability appear to be substantial limiting factors in anything widespread. Monday through Thursday...The cold front is forecasted to push through Monday morning with linger showers, especially along the coast. High pressure will gradually through Tuesday allowing for cooler and much drier weather. High pressure will slide off the coast Wednesday as another cold front is expected to approach the area Thursday as another round of showers and thunderstorms are possible, but there remains some timing differences between GFS and Euro. Overall, expect high temps in the low/mid 70s Monday and Tuesday as temperature will gradually become in the upper 70s/low 80s inland Wed and Thurs. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Short Term /through 00Z Saturday/... As of 655 PM Thursday...VFR conditions will prevail through the overnight hours with patchy of thin cirrus. With increased SE wind flow helping to draw deeper moisture into eastern NC from the south, expect stratocumulus to start to develop in the morning with some MVFR ceilings possible, especially at the southern TAF sites of KISO and KEWN. Gusty SE winds of 15-20 kt with a few gusts to near 25 knots will be possible. The combination of the deeper moisture and the oncoming front will lead to a few widely scattered showers and possibly an isolated thunderstorms Friday afternoon and evening. Long Term /Friday night through Tuesday/... As 330 PM Thurs... Unsettled weather is expected through the weekend and early Monday which will result in sub-VFR conditions as showers and thunderstorms are expected. VFR conditions is expected for most of Sunday and then Monday afternoon through mid-week. && .MARINE... Short Term /through Friday/... As of 1020 PM Thursday...Minimal changes needed to the current marine forecast at this time. The gradient between high pressure retreating offshore to our north and an oncoming cold front moving across the Ohio/Tennessee Valley region, will lead to increasing winds and seas overnight. Latest 3 km NAM and HRRR show the current SE winds of mostly 10-15 knots, increasing to 15-25 knots toward morning with seas building from 3-5 feet to as high as 5-8 feet toward morning. Small Craft Advisories were issued previously for the coastal waters south of Oregon Inlet tonight and beginning north of Oregon Inlet in the morning. SE winds 15-25 kt Friday with seas 5-8 ft. Long Term /Friday night through Tuesday/... As 330 PM Thurs... Marine conditions will gradually improve Friday night into Saturday as S winds decrease from 15-20 knots to 10-15 knots, and seas are expected to diminish to 3-5 ft Saturday afternoon. SCA conditions is expected to continue through Saturday mid-morning. Saturday night through most of Sunday, winds will remain southerly 10-15 knots, then winds will start to increase Sunday afternoon through Sunday night S 15 to 25 kts ahead of an approaching cold front. SCA conditions will be very likely Sunday night through Monday as southwest winds increase to 20 to 30 kts, with a few gusts approaching gales during this period. Waves will build to 7 to 10 feet. Winds and seas will gradually subside Monday night through Tuesday as winds become NW 10-20 knots and seas 3-5 ft. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory until 1 PM EDT Saturday for AMZ152-154- 156-158. Small Craft Advisory from 6 AM Friday to 10 AM EDT Saturday for AMZ150. && $$ SYNOPSIS...MHX NEAR TERM...CTC SHORT TERM...CQD LONG TERM...EH/BM AVIATION...CTC/CQD/BM MARINE...CTC/CQD/BM
Area Forecast Discussion
National Weather Service Marquette MI
956 PM EDT Thu Apr 11 2019 .UPDATE... Issued at 955 PM EDT THU APR 11 2019 Fcst is generally working out as expected, though there are the usual major difficulties of capturing ptype changes in the fcst. Water vapor imagery and RAP analysis show mid-level low centered over far se SD. Ahead of the dry slot wrapping n on the e side of the low, warm conveyor pcpn, separated into 2 bands, is streaming n into Upper MI this evening, but is only slowly shifting eastward. The lead band has had the more substantial pcpn into the early evening, but the second band, at the leading edge of the dry slot, appears to be becoming the more dominant one now. Some thunder is noted along this second band which is now beginning to push into far western Upper MI. As the dry slot shifts ne thru the night, the warm conveyor pcpn will shift e, bringing an end to the more significant pcpn. Latest RAP fcst soundings continue to show the transition from snow to sleet and some fzra for much of the area as this pcpn continues e and exits during the night. This transition has already begun across the s central and far w. The second band of pcpn that will be swinging across the area may end up being mostly sleet with some fzra. Would not be surprised for some lightning to accompany it. Ice accumulations from fzra should be under one-quarter inch for the rest of the night, but not out of the question that some locally higher amounts could occur. As for the headlines, will be cutting it close with some of the warning end times at 06z, but plan for now is to let that ride and include a mention of mixed pcpn continuing across the nw and central for a while longer into the night. Expect all pcpn of any note to be out of the nw and central by 09z. Delta county advy drops off at 06z. Will extend that to 09z as the back edge of the pcpn will not be e of there by 06z. && .SHORT TERM...(This evening through Friday) Issued at 255 PM EDT THU APR 11 2019 Upper air pattern consists of a closed 500 mb low over central NE this morning embedded in a deep trough over the central plains. The closed low heads north to NW WI by 00z Sat. System has not been panning out as planned and it is due to the low level dry air which has been stubborn to leave. First surge of moisture this morning made it far north as IMT and MNM, second surge made it to IWD and ESC and still not snowing at office or at SAW. In fact, leading edge keeps eroding the northward progress of the pcpn and have been trimming back the northward progression of pops all day. Trouble is the dry air will continue to be a problem for this afternoon anyway and slowed the progression of pops northward a bit along with qpf amounts adjusted downard across the north and east. Models show a 3rd surge of pcpn with warm conveyor belt setting up this evening across the central cwa and this heads east out of the area late tonight. Will still be messy with snow switching over to rain, freezing rain, sleet and snow and then switching over to all rain by morning with the dry slot moving through. Will keep headlines as is and count on the third surge to hit the area the heaviest this evening for now. Ice accumulations look to be less than a quarter of an inch tonight. Overall, this forecast has been tough and confidence continues to be low in it based on persistence of dry air which has been eroding the northward edge of pcpn and causing a strong gradient in pops and qpf. .LONG TERM...(Friday night through Thursday) Issued at 249 PM EDT THU APR 11 2019 Upper air pattern features de-amplifying upper low Lk Superior to northern Ontario on Friday night with associated 995mb sfc low over northern Lk Superior lifting to James Bay. Cold front tied to the low swings across Upper Michigan Friday night, switching any liquid precipitation back to snow from west to east. Even as upper system weakens, another shortwave and area H7-H5 q-vector convergence crosses Upper Michigan later Friday night through midday Saturday. Lingering deep moisture/cyclonic sfc-H85 nw flow and the lift with adequete over-water instability (delta t/s up to 9-11c) should keep lake enhanced snow showers going over especially north half of Upper Michigan into Saturday. Given the deep moisture around most of the day and cool temps aloft, could also see potential for instability rain/snow showers farther inland and toward Lake Michigan. Precip diminishes Saturday night as sfc-H85 high pressure takes over as southern stream system over lower Mississippi River Valley becomes primary focus. Next system lifts from the lower Mississippi River Valley to the central Great Lakes Sunday into Sunday night. ECMWF brings system far enough northwest to result in light rain/snow into central Upper Michigan. GFS and Canadian keep system too far east for any precip. Looks like dprog/DTs of models indicate steady trend toward drier weather over most of Upper Michigan since 12z/10 April model runs. Weak shortwave/sfc trough could bring light rain/snow showers on Tuesday, then another stronger southern stream system developing over the southern Plains on Wednesday may make a run into Upper Great Lakes. Currently, the GFS is most aggressive bringing the system into our area with ptype likely mainly rain. GFS-FV3 keeps the system south though as does the ECMWF, which has kept this system mainly south of the area over the last few days for all but one run. As for high temps through the period, expect normal of slightly below normal temps through Monday with slightly above normal temps Tuesday through Thursday. Min temps look to remain below freezing most areas into Monday night, with a chance of temps pushing up near freezing Tuesday night and Wednesday night. Even so, does not look really warm, so looks like we`ll have a return to the gradual thaw and freeze cycle we have seen for much of March into April. This will be good for melting snowpack and any snow we add to the snowpack over the next couple days. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 751 PM EDT THU APR 11 2019 Precipitation will continue to stream n into Upper MI this evening with the heaviest/steadiest pcpn affecting KCMX/KSAW. Precipitation will initially be in the form of SN, but will mix with or even change to PL. Some FZRA is also possible, mainly at KSAW. Pcpn will diminish from w to e overnight. While IFR and ocnl LIFR are expected at KCMX/KSAW (possibly blo airfield landing mins at times), expect conditions to vary btwn IFR and MVFR at KIWD. All terminals are likely to fall to prevailing LIFR late tonight into Fri morning before improvement to MVFR occurs Fri aftn. Gusty e winds to 20-30kt or higher are expected for much of the night, especially during the evening. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 255 PM EDT THU APR 11 2019 Easterly to northeasterly gales across Lake Superior becoming storms for a period this evening over the western two zones. Winds subside quickly Friday morning to less than 25 knots over the entire lake. 20 to 25 knot westerlies possible for a brief period Saturday morning. Otherwise winds remain light into next week, once this storm is done with. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning until 2 AM EDT /1 AM CDT/ Friday for MIZ001>005-009>011-084. Winter Weather Advisory until 8 AM EDT Friday for MIZ006-007-014- 085. Lakeshore Flood Advisory until 8 AM EDT Friday for MIZ001-003- 005. Winter Weather Advisory until 5 AM EDT Friday for MIZ013. Winter Weather Advisory until 1 AM CDT Friday for MIZ012. Lake Superior... Gale Warning until 4 AM EDT Friday for LSZ249>251-267. Gale Warning until 8 AM EDT /7 AM CDT/ Friday for LSZ240>248- 263>266. Storm Warning until 8 AM EDT /7 AM CDT/ Friday for LSZ162. Lake Michigan... Gale Warning until 2 AM EDT Friday for LMZ221-248-250. && $$ UPDATE...Rolfson SHORT TERM...07 LONG TERM...JLA AVIATION...Rolfson MARINE...07
Area Forecast Discussion
National Weather Service Nashville TN
809 PM CDT Thu Apr 11 2019 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Latest surface observations indicate winds have decreased substantially from earlier today with gusts now around 20 knots or less. Therefore have gone ahead and cancelled the advisory. Winds may increase again somewhat as the cold front currently over eastern Missouri and Arkansas approaches overnight, but should stay below advisory criteria. Otherwise, scattered light rain is developing just west of the Mississippi River, and this activity will spread east across Middle Tennessee mainly after midnight. Some increase in intensity of the precipitation is expected along with a few thunderstorms developing. However, due to the very dry atmosphere in place as shown on the 00Z OHX sounding, no strong or severe storms are anticipated. Forecast already has this covered and have only made minor tweaks based on latest obs. && .AVIATION... 00Z TAF DISCUSSION. BNA/MQY/CKV/CSV...Winds remain brisk across Middle Tennessee as we head into the evening. A cold front approaching from the west will affect the mid state after midnight. Antecedent moisture ahead of the front is quite low, so the HRRR is showing a relatively narrow band of showers coming through with the front later tonight and tomorrow morning, and have staggered the TAF`s according to the HRRR. Expect VFR wx outside of the showers thru the TAF period. Winds will diminish by tomorrow afternoon. && .OHX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 8 PM CDT this evening for Bedford-Cannon- Cheatham-Coffee-Davidson-De Kalb-Dickson-Giles-Hickman-Houston- Humphreys-Lawrence-Lewis-Macon-Marshall-Maury-Montgomery-Perry- Robertson-Rutherford-Smith-Stewart-Sumner-Trousdale-Wayne- Williamson-Wilson. && $$ DISCUSSION......Shamburger AVIATION........08
Area Forecast Discussion
National Weather Service Riverton WY
219 PM MDT Thu Apr 11 2019 .SHORT TERM...(This evening through Sunday) The low pressure center now over South Central Nebraska will continue to move northeast and away from the area. Most of the related precip has exited to the east of the area. The low cloud deck and areas of very light snow continue from RKS to CPR at the time of this writing, but should end and dissipate by around 21Z this afternoon. Meanwhile, where skies have already cleared, solar insulation will help destabilize the environment. The instability combined with the prevalent low level and ground moisture from fresh snow cover will amp up the chances of snow showers, mainly in the western half of the CWA. Negative lifted indices will mainly be in the west today with snow showers likely there. Judging by area web cams, some of these snow showers appear to be fairly heavy. An inch of snow has fallen on RPK from these snow showers so far. Two to four inches total snowfall could fall in some of the far west mtns just from these frequent snow showers. Another favored area for snow/snow pellet shower activity likely occur today will be the weakly unstable northwest flow convergent areas such as the Southern wind River Mtns for later this afternoon, including South Pass and nearby Farson, as well as snow banding developing and then pulling off the Owl Creek Mtns, and then spreading southeast across the Wind River basin later this afternoon. The air mass east of the Divide will not be that unstable, conducive for conditional symmetric instability, so the combination of the convergent flow between the cyclonic flow from the exiting Great Plains low, and the backing northwest flow to the west will cause convergence over these areas, followed by more mesoscale convergent areas to the lee of the above mentioned mtn ranges. The HRRR is among one of the models that pulls one of these snow bands right over the Riverton area for heavier local snowfall amounts later this afternoon. A low pressure center over Nebraska like this seems to, often times, correlate well with such snow banding. However, the temps at the lower elevations will be too warm to support much in the way of accumulation, just more water to add to the significant precip amounts seen over the last 24 hours in these areas. However, local low elevation amounts of an inch or less are not out of the question, possibly more. Two to four inches of snow could fall over some of the Southern Absaroka and Southern Wind River Mtns could occur with these snow bands. With the main trough still overhead and corresponding cold air aloft, additional instability induced snow showers will develop in the west Friday. Temperatures Friday and Saturday will continue to be below normal overall. Then later Saturday night and Sunday, the westerly difluent feed off the Pacific will increase behind the positively tilted ridge that will build into the area Saturday night. This will result in significant snowfall for the west Sunday with borderline advisory snow amounts for the far west mtns Sunday and 1 to 2 inches in the valleys where the snow will mix with rain. Isentropic lift will initially get the snow falling in the west Sunday, followed by more instability with the asct front. This increasing westerly flow will play out differently east of the divide. The MEX guidance already indicates 27 knot sustained winds for KCPR Sunday under the right front quad of the asct jet max. Southwest winds will increase in the Southern Wind Corridor Sunday from the Red Desert to Casper. Sunday will see a warm up east of the divide with temps reaming the same west where snow is expected. .LONG TERM...(Sunday night through Thursday) A cold front will push across the area Sunday night-Monday morning. Across the west, mountain snow and valley rain or rain/snow mix will increase in coverage and intensity Sunday in moist westerly flow. Across central Wyoming, mild and breezy to windy conditions will precede the front on Sunday with the strongest winds expected from Rock Springs to Casper, and along the east slopes of the Divide from Cody-Dubois-Lander. The frontal passage will bring snow levels down to the valley floors across the west Sunday night, and spread chances of rain and snow showers east of the Divide. An upper trough is then expected to deepen over the Rockies and Great Basin on Tuesday, with low level winds turning N-NE, enhancing precipitation chances across favored upslope areas (Lander, Casper, Thermopolis). 11/12z ECMWF shows a less chaotic trough than the GFS on Tuesday, keeping energy more consolidated towards the Four Corners. This scenario would put the heaviest precipitation, along with some thunderstorms, roughly along a Rock Springs-Lander-Casper line and southward. Temperatures will remain mild enough to see either rain or a rain/snow mix across the lower elevations on Tuesday, before changing over to mostly snow Tuesday night. A cool and unsettled N-NW flow is expected to prevail on the backside of this system Wednesday, with chances of rain/snow showers across the area. An upper ridge is then expected to usher in warmer and drier weather on Thursday. GFS on the other hand, shows a more northerly track which will lead to more activity in the western mountains and valleys as well as areas est of the divide, and an increase in lingering activity for Wednesday and Thursday. This would lead to cooler temperatures for the end of the period and much more activity to deal with. As usual the picture should become clearer in the coming days. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) VFR conditions will be predominant over most of the area for the rest of this afternoon with the exception of KCPR whose MVFR /IFR ceilings will linger through the evening into late tonight. Isolated to scattered afternoon and evening snow showers are expected, especially across the northwestern/central mountains sliding southeast into adjacent foothills and portions of the Wind River Basin. Will have VCSH in most terminals to account for this possibility with this activity ending for the most part by around sunset. Winds will be breezy in the afternoon from the northwest to north in most locations, but weaken during the evening. A repeat of snow shower activity is expected in the far west again by Friday afternoon. && .FIRE WEATHER... Bands of snow showers will occur during the rest of today and Friday over the western mountains. Some of these showers will make it across zones 277, 278, 279 and 283 this afternoon. Gusty north winds will also continue over all but far western portions. Mixing and smoke dispersal will generally be very good, with fair to good conditions over zones 280 and 281. Significant snowfall is likely in the west Sunday and Sunday night along with warmer temperatures east of the Divide and increasing wind along zones eastern zone 279, as well as zones 289, 280, and 300. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Lipson LONG TERM...Hulme AVIATION...Hulme FIRE WEATHER...Lipson
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday) Issued at 316 PM CDT Thu Apr 11 2019 Early this afternoon an intense upper low was located across northeast NE. Strong low-level CAA across the Plains were keeping temperatures in the 40s across much of the CWA along with wrap around stratus cloud cover. The wrap around precip was moving northward across northwest KS into central and western NE. Blizzard conditons continued from eastern CO through western NE into SD and MN. Tonight, skies will clear from south to north across the CWA late this evening and through the early morning hours. Winds will switch to the northwest and will continue to be gusty through the evening hours. Temperatures across central NE were only in the upper 20s and lower 30s this afternoon. This airmass will advect southeast across the CWA Tonight. The winds will begin to diminish a bit through the early morning hours of Friday and low temperatures will drop into the upper 20s to lower 30s across the entire CWA. If winds decrease under 10 KTS then temperatures may fall a few degrees lower than forecasted. Due to the sub-freezing temperatures across the CWA, I have issued a freeze warning for the entire CWA from 11 PM through 10 AM Friday. The winds combined with a drier airmass should prevent frost from forming even though temperatures will drop below freezing across the CWA during the early morning hours of Saturday. Friday, the upper level low will will shift northeast across MN into western lake Superior. An upper level trough will amplify across the southwestern US. High temperatures will continue to be cool on Friday, with upper 40s north to lower to mid 50s south, as the low-level CAA continues across eastern KS ahead of a surface ridge of high pressure building southeast across the state of KS. west-northwesterly surface winds will begin to diminish during the afternoon hours. .LONG TERM...(Friday night through Thursday) Issued at 316 PM CDT Thu Apr 11 2019 Friday night the winds will become light and with clear skies temperatures will fall below freezing across much of the CWA. East central KS may remain a degree or two above freezing, but there will be a potential for frost formation across the entire CWA. Saturday through Sunday, The upper trough across the southwestern US will lift east-northeast across west TX into southwest MO by 12Z SUN. The 12Z NAM is in the agreement with 12Z ECMWF on the track of the upper low. The light rain will be moving northeast from south central KS into east central KS during the afternoon hours of Saturday and continue expanding northeast as the upper level low tracks northeast across southwestern TX into southern OK. If surface temperatures were cooler then there would be the potential for heavy snow band to develop across our southeast counties. However, forecast soundings show boundary layer temperatures remaining in the mid to upper 30s, thus the precipitation will fall in the form of rain. I cannot rule out a bit of snow mixing in across portions of east central KS towards 12Z SUN, before the rain shifts east of the CWA during the mid and late morning hours of SUN. The northwest edge of stronger frontogenetical forcing within the TROWAL region of the upper low will only extend along and east of the KS turnpike, thus much of the western and north central counties will remain dry. The 12Z GFS model tracks the upper low a bit farther east and only brings the steady rainfall into the southeast counties of the CWA Saturday night. As the upper low tracks northeast into the upper Midwest late Sunday afternoon, skies should clear from west to east across the CWA. Highs on Saturday will only reach the lower to mid 50s as cloud cover increases through the day. Highs on Sunday will warm into the mid to upper 50s with insolation in the afternoon. Sunday night through Tuesday, an upper level ridge will amplify across the Plains. A lee surface trough will deepen across the central and southern high Plains. Southerly winds will help to warm highs into the lower to mid 70s Monday and Tuesday. Tuesday night through Thursday, An upper level trough will dig southeast from the Pacific northwest into the southern and central Plains. Ascent ahead of the H5 trough will provide the CWA with a chance for showers and possible thunderstorms Tuesday night into Wednesday morning. A surface cold front will move southeast through the CWA Tuesday night into Wednesday. Highs on Wednesday across east central KS will reach around 70 before the surface front moves through, with highs in the lower 60s across. The upper trough will lift northeast into the OH River Valley on Thursday bringing an end to our rain chances. Northerly surface winds will keep highs on Thursday in the upper 50s to lower 60s && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 633 PM CDT Thu Apr 11 2019 VFR prevails through forecast period. Stratus on the backside of the surface low will gradually dissipate and lift northward late this evening, although confidence is somewhat low on timing with the latest RAP and HRRR models trending too quickly with skies clearing. Sfc westerly winds were increased overnight into Friday with gusts up to 30 kts throughout period. && .TOP WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 11 PM this evening to 10 AM CDT Friday for KSZ008>012-020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...Gargan LONG TERM...Gargan AVIATION...Prieto