Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/17

Area Forecast Discussion...Updated
National Weather Service Billings MT
842 PM MDT Wed Apr 26 2017 .UPDATE... One wave of showers is now approaching Billings and a second is moving through Livingston at this time. RAP merges these two features in the Billings area and keeps precipitation going all night over central zones, while most of the other models push these waves through, dissipating by midnight and trending pops lower overnight before next wave of energy builds in tomorrow morning from the southwest. Split the difference between these solutions and kept chance type pops in for areas west of Hardin overnight following late evening likelies. Like the trend of increasing pops from the southwest early to late morning tomorrow with broad diffluence and QG forcing overspreading surface convergence and low level isentropic ascent. May be a bit slower than previous forecast based on 00z models so slowed progression down a few hours. Overall should be a wet day over the western 2/3 of the forecast area Thursday. Snow...Temperatures overnight will be held up by increased cloud cover so looks like snow accumulations will be little to none below 6000 feet tonight, though much of the area will see at least a mix of rain/snow overnight into tomorrow morning. Best chance for light accumulations will be in the Beartooth and Bighorn foothills and valleys. No changes to the going Winter Storm Watch this evening. Chambers && .SHORT TERM...valid for Thu and Fri... Low clouds have been stubbornly hanging around over most of northeastern Wyoming and eastern Montana. Had to adjust afternoon high temperatures down several more degrees on this update given the persistent cloud deck. A batch of rain/snow showers moved through Billings late this morning bringing around 0.10 inches of liquid. A line of showers and isolated thunderstorms has developed from Nye northward to Harlowton which is pushing into the central Plains. Troughing begins to develop east of the Divide this evening as an upper-level shortwave digs into Idaho. Surface low begins to develop over southeastern Wyoming with a trough axis northward through the Bighorns and into south central Montana. Isentropic lift begins to generate the highest qpf area from Sheridan County northwestward through Yellowstone county by Thursday afternoon. This trough axis will remain quasi-stationary through Friday morning. Then it will begin to push southwestward toward the Beartooth/Absaroka foothills by Friday afternoon. Models have trended cooler with this system particularly over northern Wyoming with a rain to snow transition in Sheridan expected some time on Thursday. This significantly increases the expected snowfall accumulations for Sheridan and southern Big Horn County. With this update, I have added those areas to the current Winter Storm Watch for Thur-Fri. Expecting 6-10 inches of snowfall for foothills and areas west of Interstate 90, with 4-6 inches in eastern portions of those counties. Still expecting Bighorn Mountain locations to see 12 to 18 inches of snowfall accumulation through Friday. Still some uncertainty whether enough snow will occur in lower-elevations to warrant any advisories, so I will let the next shifts take a look at that. Walsh .LONG TERM...valid for Sat...Sun...Mon...Tue...Wed... Building heights over the area on Saturday as energy near the 4 corners region begins to shift east. This will begin to dry out the airmass and surface high pressure will be in place to limit mixing but clearer skies will begin a warmup. Flow regime for Sunday through Tuesday will be northwesterly with disturbances bringing showers and temperatures closer to seasonal normals. Tuesday disturbance is accompanied with a bit more upslope which allows for better precipitation amounts but nothing significant compared recent events. Another pattern shift for Wednesday as a broader ridge shapes up over the western US while northerly flow still keeps temperatures cool over Montana and Wyoming, it does however trend drier with a few diurnal showers due to high soil moistures. The ridge begins to shift eastward towards the weekend which could bring a round of above normal temperatures. borsum && .AVIATION... Scattered showers and isolated thunderstorms will move across the western and central sections of the forecast area this evening impacting KLVM and KBIL before dissipating late this evening. Another round of showers resulting in MVFR conditions will move into the area later tonight and especially by mid morning Thursday. Otherwise, VFR conditions will prevail for most areas tonight. However, the mountains will be obscured throughout the night. Hooley && .PRELIMINARY POINT TEMP/POPS... Thu Fri Sat Sun Mon Tue Wed ----------------------------------------------------------- BIL 036/047 033/045 034/053 036/059 040/056 039/055 038/060 67/O 86/O 42/W 11/B 33/W 33/W 32/W LVM 032/047 030/045 026/053 033/057 036/054 033/053 033/057 56/O 47/O 42/W 13/W 33/W 33/W 32/W HDN 035/048 034/049 033/056 035/061 039/058 039/057 038/061 36/O 86/O 32/W 11/B 33/W 34/W 32/W MLS 034/057 034/055 034/058 036/061 041/059 039/057 039/060 12/O 33/O 21/B 11/U 33/W 13/W 22/W 4BQ 031/053 032/051 033/056 031/059 039/057 038/055 036/059 12/R 44/O 21/E 11/U 33/W 24/W 22/W BHK 025/054 028/052 030/056 030/059 037/056 035/054 035/057 11/B 11/E 11/E 11/U 33/W 13/W 21/B SHR 032/043 030/042 028/047 029/054 036/052 035/051 035/055 37/O 87/O 42/W 11/B 33/W 34/W 32/W && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Storm Watch in effect from 6 AM MDT Thursday through Friday evening FOR ZONE 38. WY...Winter Storm Watch in effect from 6 AM MDT Thursday through Friday evening FOR ZONES 98-99. && $$
Area Forecast Discussion
National Weather Service Des Moines IA
623 PM CDT Wed Apr 26 2017 ...Updated for 00z Aviation Discussion... .SHORT TERM.../Tonight through Thursday/ Issued at 359 PM CDT Wed Apr 26 2017 The weather will turn quite active into the weekend and early next week, but initially the concerns through tomorrow will be precip trends southeast this evening and then frost potential southwest into Thursday morning. The current situation has a deep PV anomaly/short wave moving through TX with a large area of kinematically forced lift moving through the MS Valley, including some right entrance region effects from a small Upper MS Valley jet segment. Much of the warm/theta-e advection and frontogenetical forcing is south and east of Iowa, and should remain that way tonight. The mid level mechanically forced lift may just brush far southeast sections this evening with only chance PoPs. Frost is a concern southwest overnight but there are questions with regard to wind, temps and cloud cover. HiRes window ARW/NNM runs suggest some clearing southwest half overnight, however the ESRL HRRR, HRRR and RAP are both more aggressive and the current stratus shield still extends well into NE. Winds may not drop below 8kts and mins are even marginal with no lower than 34F expected. With these inputs in low confidence have opted to not issue a headline for the time being. The cloud trends would be the main concern and can be further evaluated this evening if need be. Although IA will be thoroughly embedded in the broad mean trough, a subtle short wave ridge through the MO Valley may give us a brief glimpse of sun Thursday before the forecast turns. .LONG TERM.../Thursday night through Wednesday/ Issued at 359 PM CDT Wed Apr 26 2017 The overall pattern will have changed little heading into the later periods with strong Pacific NW jet continuing to feed short waves into the base of the mean trough. The next wave of forcing is expected to lift through the Plains and MO Valley Thursday Night with a strong baroclinic zone lifting south to north into IA. The phasing of deep moisture and lift is not there all the time, but should result in at least some precip into Friday. Have also mentioned some frost north with temps at or below freezing and skies mostly clear for a good deal of the night. After a relative lull to start the weekend, the long wave trough will deepen and amplify leading to strong MO Valley cyclogenesis into IA. The ECMWF and GFS are in good agreement and fairly impressive spreading deformation zone precip into NW with strong thermodynamic forcing just to the south and east into central IA. Both models depict tremendous theta-e advection and frontogenetical forcing leading to likely PoPs into Sunday, even at this time range. WPC Day 5 QPF forecasts suggest widespread 1-2" accumulations may occur through the weekend. Temperatures will be right on the brink of being cool enough to support snow, so there continues to be at least a mix wording into early Monday morning. Timing as of now suggests the mid/upper level core of the low will be over IA Sunday Night, which would be a more favored time for snow rather the during nearly early May daytime heating. Gusty winds will also need to be watched with a strong MSLP gradient just ahead of and then behind the low. Confidence is certainly not high, with a noted dry slot also rotating into IA, but strong forcing and precip rates at night could lead to accums and overwhelm any melting at night. Some low end PoPs linger into Tue and Wed but forcing is somewhat non-descript as another NW flow wave attempts to deepen the central CONUS mean trough. Temperatures through the extended will certainly not be warm with cool and wet the primary themes, even beyond valid forecast period. && .AVIATION.../For the 00Z TAFS through 00Z Thursday evening/ Issued at 623 PM CDT Wed Apr 26 2017 MVFR ceilings will prevail at all terminals overnight with perhaps some high IFR ceilings at KMCW. A few showers will also pass over KOTM this evening before the showers pivot to the east. Drier air arriving on winds from the northwest will allow for clouds to break and ceilings to rise into VFR from the southern terminals to the northern terminals through the day Thursday. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Small LONG TERM...Small AVIATION...Ansorge
Area Forecast Discussion
National Weather Service Green Bay WI
1024 PM CDT Wed Apr 26 2017 Updated aviation portion for 06Z TAF issuance .UPDATE... Issued at 909 PM CDT Wed Apr 26 2017 Made the previously-mentioned changes to precipitation chances overnight into Thursday, with higher POPs and QPF in our western counties. Also adjusted temperatures down a few degrees, which resulted in greater ice/snow accumulations. Issued a winter weather advisory for Vilas, Oneida, Lincoln and Forest counties from 09z-17z/Thu, which matched up well with headlines that DLH and MQT had issued earlier. UPDATE Issued at 629 PM CDT Wed Apr 26 2017 Watching a fairly consistent trend of the meso-models wrapping pcpn farther back to the west late tonight into Thursday morning. If this is correct, and if temperature forecasts reach current forecast values or get a little cooler, we may need to consider winter weather headlines for a mix of freezing rain, sleet and snow in our far northwest counties. Will monitor this over the next hour or two. && .SHORT TERM...Tonight and Thursday Issued at 235 PM CDT Wed Apr 26 2017 The latest rap analysis and satellite/radar imagery show low pressure over northeast Wisconsin early this afternoon, with a trailing cold front extending south into Missouri. Widespread rain is about to exit far northern WI ahead of the low, and a significant break exists between this area of rain, and the next area, which is surging northeast over southern Illinois. This secondary area is ahead of another surface wave positioned over southern Missouri. Looking to the northwest, colder air lies just upstream, with temperatures in the upper 20s to lower 30s from the Arrowhead of Minnesota to Ironwood. Several obs are reporting snow in these areas. Forecast concerns revolve around precip trends with the arrival of the secondary low tonight, and potential for wintry precip over north-central WI as colder air filters in behind this low. Tonight...A complicated forecast. Low pressure over northeast Wisconsin will depart over eastern Lake Superior this evening. Between this system and the arrival of a secondary low, will likely see a lull in the widespread precipitation, though some occasional drizzle will likely occur over central and north-central Wisconsin. The secondary low will move towards southern Lake Michigan late tonight and bring another swath of widespread precipitation to the area. The heaviest rain remains forecast for eastern WI, where upwards of a half inch of rain could fall. Amounts will be considerably less over central and north-central where north winds behind the low will draw in colder air from northwest Wisconsin and northern Minnesota. Because of these colder temps, potential remains for wintry precipitation, mainly over Vilas and western Oneida/Lincoln counties. A small window may start to open late tonight, when temperatures cool at the surface and more widespread precipitation arrives, for accumulating wintry precip in the form of snow/sleet/and freezing rain. Think any accumulations will mainly be confined to grassy and elevated surfaces, though cannot rule out patches of minor accumulations on roadways in the heavier precip rates. The potential for slippery stretches on roads will likely end by 8am as road temps warm with solar insolation. Because of the narrow time window, and uncertainty revolving around temps/precip coverage, will continue to highlight the threat of slippery roads in a SPS. Thursday...Low pressure will continue to lift north over Lake Michigan and into Lake Superior. Widespread precip will likely be lifting north on the western flank of the low across much of the area during the morning, with some wintry precip over north-central WI. Precip will exit during the afternoon, but mostly cloudy conditions will linger. Because of the precip and cold advection, temps will only rise into the middle 30s in the north to middle 40s near the Lake. .LONG TERM...Thursday Night Through Wednesday Issued at 235 PM CDT Wed Apr 26 2017 The first storm will continue to move away from the region Thursday night. Some wrap around moisture lingering across the far north to support small chances of precipitation (mainly over Vilas County) Thursday night. Left Friday morning dry across the north, but could not rule out a few flurries. There was a change in the forecast for Friday afternoon into Friday night as system passes to the south. Several models depicting light rain across east-central Wisconsin, and as far north as Green Bay. Have added a chance of rain to account for this feature. High pressure will then dominate the weather pattern Saturday into Saturday evening. Next system approaching from the south a little quicker than previous runs. This would support more snow at the onset, especially across the north late Saturday night into Sunday morning. Do think the heaviest precipitation will arrive by mid morning across the north, thus any accumulation would be on the light side and not cause too many impacts. Will need to see if the system speeds up over the next day to see if more snow accumulation would need to be added to the forecast. It appears Sunday is going to be a washout with periods of rain, mixed with snow across the north during the morning. System will move across the region Sunday night into Monday morning. Dry slot may move across our southeast counties after midnight. Will also need to monitor thunder prospects across our southeastern counties as well. Do not have thunder in the forecast at this time since it is still pretty far out. Across the north, light snow is expected at times with some snow accumulation possible Sunday night into Monday morning. Any lingering precipitation comes to an Tuesday with dry conditions expected on Wednesday as high pressure dominates the weather pattern. Below normal temperatures are expected through much of the period. In matter of fact, the latest numerical guidance indicated no 60s or 70s during the next seven days at Green Bay. && .AVIATION...for 06Z TAF Issuance Issued at 1016 PM CDT Wed Apr 26 2017 Widespread IFR/LIFR conditions covered all but far eastern WI late this evening, and ceilings should drop there within the next few hours, as the cold front shifts through and rain develops. Another area of significant precipitation will arrive overnight into Thursday morning, and models are still indicating that it will overspread our western counties late tonight into early Thursday. While most of the region will see rain, our northwest counties, including the RHI TAF site, will likely see a mix of freezing rain, sleet and snow late tonight into Thursday morning, as temperatures drop below freezing. It will be a close call for AUW/CWA, as freezing precipitation may develop just to the west. At the least, it appears that a rain/snow mix will develop there Thursday morning. Some improvement in ceilings and visibilities are likely on Thursday afternoon as the precipitation pulls out to the northeast. && .GRB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 4 AM to noon CDT Thursday for WIZ005-010-011-018. && $$ UPDATE.........Kieckbusch SHORT TERM.....MPC LONG TERM......Eckberg AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Grand Rapids MI
1028 PM EDT Wed Apr 26 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 325 PM EDT Wed Apr 26 2017 A few showers and thunderstorms can be expected through Thursday afternoon as a cold front moves through. Conditions will dry out for a short period late Thursday through early Friday. Low pressure will approach on Friday and bring a chance of rain. A much better shot at widespread rain will come late Saturday through Sunday as another low pressure area tracks across Lower Michigan. && .UPDATE... Issued at 1028 PM EDT Wed Apr 26 2017 Lowered POPs and QPF overnight and into Thursday morning. Models have been trending drier and last few runs of the HRRR and other high res models show bulk of precip missing Lower Michigan to the west tonight and tomorrow. Severe threat also appears to be rather low overnight despite greater than 50 knots of 0 to 6 km shear, as instability is lacking. Instability appears to be limited on Thursday as well but we Will have to watch for narrow line of convection late Thursday morning or afternoon that could have strong gusty winds as indicated by the hi res NMM/ARW. && .SHORT TERM...(This evening through Friday night) Issued at 325 PM EDT Wed Apr 26 2017 Our focus with this forecast package is on the waves of showers/storms through Thu, and the chance of rain coming back in for Fri/Fri night. There is a dying line of showers over Central Lower that is at the tail end of an upper vort moving NNE away from the area. This seems to be just a bit too far north to tap 1000 j/kg of low level CAPE over the srn portion of the area. This line seems to be some what of a weak cool front that extends down S of the area. We can not rule out another shower/storm popping up, but we do not expect widespread showers/storms until after 00z tonight. We are expecting a wave of showers/storms to arrive after 00z from the SSW that are currently in Srn Il. These are associated with another upper/sfc wave that will move NE through the evening. The associated low level jet will nose up into the area and strengthen. The sfc based instability that we see now will diminish, and this wave will feature mainly elevated instability with it. This will limit the severe potential with it. There is some decent shear with healthy wind profiles up the column. The decent wind profiles will keep an isolated wind threat in, if it could punch through the stable near sfc layer. Heavy downpours will be possible too with PWATS up around 1.5 inches. We will likely see a lull in the rain for late tonight and early Thu as the nose of the low level jet moves out, and the sfc low remains to our west. Heavy widespread rainfall looks to stay over WI. We will see the main cold front push through late Thu morning and early Thu afternoon. This will likely develop a bkn line of showers/embedded storms ahead of it with some diurnal heating taking place before it pushes through. Forecast soundings do not not support much of a severe weather threat with thin CAPE profiles. The wind aloft however keeps a threat in before the front moves through. The front looks like it should clear the CWFA by 19z Thu. A few showers will remain in the afternoon to the NW as the upper wave moves through. We should end up dry Thu night with rain chances then increasing on Fri again. The current upper system affecting us moves out, and the leading short wave with the next upper system approaches. Low level moisture is not exciting, but there may be just enough for a few light rain showers to make it to the ground into Fri night. Thunder chcs look too low with this to include in the forecast for now. .LONG TERM...(Saturday through Wednesday) Issued at 325 PM EDT Wed Apr 26 2017 Only small changes were made to the going grid forecast, as the models are in good agreement and fairly steady. Active weather is expected through much of the long range forecast. Showers will be ongoing across Southern Lower Michigan Saturday, with thunderstorms becoming possible Saturday night through Sunday night. Widespread rain, could be heavy at times through the weekend. Showers will continue into Tuesday. Rainfall totals of one to two inches are likely Saturday night through Sunday night with locally higher amounts possible. Temperatures should be fairly close to normal through the long range forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 756 PM EDT Wed Apr 26 2017 VFR conditions expected to continue through 06Z although scattered showers and thunderstorms are possible late this evening. Periods of MVFR are possible after 06Z as ceilings lower blo 3000 feet at times. Looks like more scattered showers and a few thunderstorms again after 12Z. Southwest to south winds overnight around 10 knots then going west during Thursday with gusts 20 to 25 knots. && .MARINE... Issued at 325 PM EDT Wed Apr 26 2017 We are extending the Small Craft Advisory out through 06z Fri morning with this forecast package. The initial advisory was mainly for the winds out ahead of the system. We are now to the point that the winds behind the system on Thursday need to be dealt with. These will be the strongest Thu afternoon, and the waves will come down enough finally Thu night. && .HYDROLOGY... Issued at 325 PM EDT Wed Apr 26 2017 Confidence continues to grow that we will have an increasing flood risk as we head into the weekend and next week. The GFS, GEM, and ECMWF all have been indicating a pattern that will produce significant rainfall for our region, likely on the order of 2" to 3" or more. When that much rain falls across the entire reaches of the major basins - Grand, Muskegon, and Kalamazoo - there will be some significant rises. Trends will continue to be monitored. Smaller rivers and streams are going to be highly responsive to this type of rain, with abrupt rises possible. Residents along smaller rivers and streams should be aware of the risk for these types of changes late into the weekend and early next week. At this point it is too early to tell exactly how high the rivers will get, but flood stage may be exceeded at many locations potentially. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Small Craft Advisory until 2 AM EDT Friday for LMZ844>849. && $$ UPDATE...Ostuno SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...63 AVIATION...Ostuno HYDROLOGY...Hoving MARINE...NJJ
National Weather Service Jackson KY
1054 PM EDT Wed Apr 26 2017 .UPDATE... Issued at 1054 PM EDT WED APR 26 2017 The latest HRRR and other CAMs remain in decent alignment with latest radar trends. These models still bring showers and perhaps a few thunderstorms into the Lake Cumberland region by 11Z to 12Z. This line could even slow down some, as the upper level trough does take on a more negative tilt. The next issue tonight will be valley temperatures, and did opt to lower from previous forecast given the latest trends. However, it will be tricky to time the actual low given the cloud cover moving into the region. Overall think we could still be looking at a 10 degree split from the ridges to the valleys. Otherwise, gravitated grids to latest obs and trends. && .SHORT TERM...(This evening through Thursday night) Issued at 300 PM EDT WED APR 26 2017 The short term portion of the forecast will feature above normal temperatures and a period of showers and storms on Thursday. A fast moving cold front is forecast to move across the Ohio and Tennessee valley regions during the day on Thursday. The precipitation should begin moving into our southwestern and western counties early Thursday morning, and should be exiting the area early Thursday evening. The latest model data is suggesting that instability should be elevated across the region, which would help mitigate any threat of severe weather. However, wind decent wind shear may exist tomorrow while the front is passing through, so an isolated severe storm with damaging wind gusts cannot be ruled out at this time. With precipitation and extensive expected to spread across the area tomorrow, temperatures will not be able to warm nearly as much as they have the past couple of days, but we should still highs max out in the low to mid 70s, which is still slightly above normal for this time of year. Low temperatures the next two nights should be in the 50s and 60s tonight, and in the 50s tomorrow night. Southerly winds will begin to pick up and become gusty overnight and tomorrow, as the front approaches and the regional pressure gradient strengthens. Isolated gusts of 15 to 20 mph cannot be ruled out. .LONG TERM...(Friday through Wednesday) Issued at 333 PM EDT WED APR 26 2017 Southwest flow will be in place aloft across eastern Kentucky Friday through the weekend with ridging off the southeast coast while a deep trough gets carved out over the central CONUS. At the surface, a quasi-stationary frontal boundary located initially along the Ohio River will sag south into the area Friday night. After a dry and warm day on Friday, shower/thunderstorm chances increase overnight Friday night, especially over the Bluegrass and Gateway regions which will lie closest to the boundary. Models indicate decreasing instability and shear parameters during the night so severe weather is not a major concern. Forecast models lift the warm front to our north Saturday into Sunday placing our area firmly in the warm sector and likely capped from much if any convective development, although cannot rule out a shower or storm completely. Temperatures will warm well into the 80s both days, along with dewpoints in the 60s, making it feel very summer-like. Showers/storm chances then increase quickly Sunday night into Monday morning as the potent storm system wraps up and tracks into the Great Lakes, forcing a cold front across the local area. Models show quite the wind field accompanying the frontal passage so despite unfavorable timing and insignificant instability, will have to monitor this system closely for a strong wind threat as the front passes through. The front quickly clears the area on Monday leaving behind a cooler, less humid airmass. After a brief respite Monday night and Tuesday, both the GFS and ECMWF indicate another shot at showers developing by the middle of next week as an open wave drops into the central CONUS, renewing southwest flow aloft over our area. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 734 PM EDT WED APR 26 2017 VFR conditions are the story to begin the period and will remain that through much of the night. However, a strengthening LLJ will introduce the potential for LLWS overnight under calm conditions. The system that will help induce the jet will also bring the chances of showers and thunderstorms by around the dawn hours in the morning. Right now sticking with low end MVFR, but perhaps IFR would not be out of the question at times in heavier storms. Also winds will be light to begin the period, but we could see some gusty winds with any stronger storms. Also winds will veer around to the west on the back of the front tomorrow afternoon and could be gusty in the afternoon given good mixing. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...AR LONG TERM...ABE AVIATION...DJ
Area Forecast Discussion
National Weather Service Marquette MI
832 PM EDT Wed Apr 26 2017 .SHORT TERM...(This evening through Thursday) Issued at 431 PM EDT WED APR 26 2017 WV imagery and RAP analysis indicated a mid/upper level trough from the eastern Dakotas through Oklahoma resulting in ssw flow through the wrn Great Lakes. One of several shortwave troughs lifting through Upper Michigan supported an area of light to moderate rain through the nrn cwa. There was a lull in the pcpn upstream over WI with mainly patchy light rain or drizzle. The next main upstream shrtwv was moving into sw Missouri. At the surface, 994 mb low pressure was located over ne WI with a trough extending to the ne through centrl Upper Michigan into se Lake Superior. Much colder air prevailed behind the trough over the nw cwa with temps in the mid 30s while temps had climbed into the lower to mid 50s over the south and east. The short range models have trended slightly to the west with the area of heavier pcpn associated with the shrtwv lifting into the area as the sfc low moves through Lake Michigan. Expect the heavier band of pcpn mainly btwn 09z-15z. Additional QPF in the 0.25-0.50 inch range will be likely over much of the area from late tonight through Thursday morning. Temps should climb slightly this evening central as the low lifts to the northeast but should fall off by late evening as low level caa increases behind the low. Although there is still some uncertainty with where the strongest temp gradient will set up, there is a high enough probability that temps will be at or below freezing over the higher terrain of the west by late tonight. to expand the winter weather advisory into wrn portions of Marquette county. Similar to today, the strongest icing is likely on trees and power lines as the ground remains warm enough to minimize icing on the roads. Overall ice amounts could still approachin a quarter inch in some locations. A changeover to snow and sleet is also expected over the west third as the warm layer aloft shrinks and dissipates. .LONG TERM...(Thursday night through Wednesday) Issued at 410 PM EDT WED APR 26 2017 Main weather concern in the extended will be below normal temperatures along with a stronger system possible with a wintry mix Sunday into Monday. Thursday night: The low pressure system that has been bringing all of rain and wintry mix to portions of the area will exit to the northeast during this time period. Moisture will continue to wrap into the area through much of the night; however, the better forcing will lift to the north and east with the low. 850mb temperatures will drop into the -7C to -9C range, which will be sufficient to allow for lake effect rain and snow showers for west to west southwest wind favored locations. This would be mainly focused over the Keweenaw Peninsula and at this point it looks as though the QPF and snow ratios would be fairly low. Friday through Saturday: A surface ridge and drier air is expected to build into the area during this time period allowing skies to become partly cloudy with only minor chances for rain and snow showers, again, the main focus would be early in the day Friday over the Keweenaw Peninsula. Temperatures are expected to be slightly below normal through this time period. Saturday night through the extended: Low pressure is expected to develop over the Southern Plains late Saturday night and slide through the Upper Great Lakes Sunday into early next week. Models are in general agreement on a bigger system sliding through the area; however, timing and placement differences continue with the solutions. The GFS/Canadian and the latest EC all have similar tracks and timing; however, the GFS is deeper with the surface low and upper level low and the Canadian is a bit farther west than previous model runs. These models each have the low moving out of the area Tuesday afternoon. The previous runs of the EC have been keeping the surface low and 850mb low farther west, taking the low over the western U.P. If the GFS/Canadian and now the latest EC are correct there could be substantial accumulating snowfall across portions of the west half of the U.P.; however, if the older EC solutions are correct, then most areas may end up seeing mainly rain with maybe even some dry slotting expected over the east half. Until better sampling occurs with this system it is likely that there will continue to be variances in the models, with improvement expected by Friday as the wave of energy is better sampled. Consensus is still the way to go at this point in the extended due to the reduced confidence in the system track. This will give a mix of rain and snow central, rain changing to snow west and mainly rain east. Dry weather is then expected Wednesday into Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 827 PM EDT WED APR 26 2017 A sfc trof over Upper Michigan will result in poor conditions at KIWD/KCMX/KSAW through this fcst period under periods of showers and considerable low-level moisture in the vcnty of the trof. IWD/CMX will be down to IFR with periods of LIFR tonight into Thu morning. LIFR conditions should continue at SAW through tonight with some improvement Thu morning as winds become nnw with a more downslope component. Shallow cold air will filter into western Upper MI for a change to -fzra at KIWD and KCMX tonight. Expect modest improvement late Thu at KIWD and KSAW as drier air from the west allows cigs to improve to low end MVFR. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 524 AM EDT WED APR 26 2017 Northeast gales to 45 knots continue over west and central Lake Superior into this evening. By late tonight into Thursday morning winds will begin to subside to 20 to 30 knots as winds become northerly. Late Thursday through Friday, winds will further decrease to 10 to 20 knots as winds become westerly. Winds of 10 to 20 knots are expected through the weekend but could see much stronger winds to at least 30 kts next Monday as strong low pressure system lifts across the Great Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 1 PM EDT /noon CDT/ Thursday for MIZ001>004-009-010-084. Winter Weather Advisory until 1 PM EDT Thursday for MIZ005. Lake Superior... Gale Warning until 11 PM EDT /10 PM CDT/ this evening for LSZ162. Gale Warning until 3 AM EDT Thursday for LSZ264. Gale Warning until 2 AM EDT Thursday for LSZ263. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...KEC AVIATION...Voss MARINE...JLA
Area Forecast Discussion
National Weather Service Morristown TN
935 PM EDT Wed Apr 26 2017 .DISCUSSION...Forecast mostly on track this evening as we await the arrival of showers and thunderstorms moving in from the west. Still expecting activity to weaken as it moves into our area. The only change to the forecast was to slow the onset of precip. Previous grids had slight chance pops in for Plateau by 2 am EDT Have now pushed that back until 5 am EDT based on latest RAP and HRRR runs which both show later arrival. All other elements look good. Will send out new zones to reflect aforementioned changes. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 64 76 55 85 / 50 70 10 10 Knoxville McGhee Tyson Airport, TN 62 76 55 85 / 20 50 10 10 Oak Ridge, TN 63 77 54 85 / 30 50 10 10 Tri Cities Airport, TN 54 77 53 85 / 0 40 20 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...None. TN...None. VA...None. && $$ SR
Area Forecast Discussion
National Weather Service San Francisco Bay Area
852 PM PDT Wed Apr 26 2017 .SYNOPSIS...Isolated showers have ended in most areas, but remain a possibility over the hills from Santa Clara County southward this evening. Otherwise, dry weather is forecast through the weekend and into next week. Locally breezy conditions are expected over the next couple of days. Strongest winds will be near the coast during the afternoon and early evening hours, and in the hills late night and morning hours. A warming trend is forecast through the weekend and into early next week as high pressure builds over the region. && .DISCUSSION...As of 8:50 PM PDT Wednesday...KMUX radar indicates isolated light showers over the southern Diablo Range at the present time. The latest WRF and HRRR models forecast continued isolated shower activity across the southern Diablo Range and over the hills of Monterey and San Benito Counties through late evening. But for the most part, dry weather is expected overnight. Dry weather is then forecast regionwide for the remainder of the week, through the upcoming weekend, and on into next week. In addition, expect much warmer temperatures by the weekend, with warm, dry weather expected to continue into next week as high pressure builds over California. But before the warmest weather develops, our region will experience blustery conditions for the remainder of the work week, with locally gusty winds at the coast and in the hills. An upper low is forecast to gradually deepen over the Intermountain West over the next few days. Meanwhile, an upper level ridge will be amplifying off the west coast. In between these two pressure centers, brisk northwest flow will develop across California. West to northwest winds will increase along our coast on Thursday afternoon and remain gusty through Thursday evening. Coastal wind gusts as high as 35 mph are possible during this time. Winds will then gradually decrease near the coast on Thursday night, but at the same time north winds will increase in the hills. Wind gusts up to 40 mph are possible across elevations above 1000 feet late Thursday night and Friday morning. This same wind cycle is forecast to repeat from Friday afternoon through Saturday morning, with another round of brisk winds expected near the coast Friday afternoon and evening, and in the hills late Friday night and Saturday morning. Although locally blustery conditions are forecast over the next couple of days, winds are expected to remain below advisory levels in most areas. Winds will decrease in all areas by Saturday afternoon. Temperatures will warm over the next few days as drier air moves in and we see more sunshine. But the most robust warming will occur on Saturday as the upper ridge offshore begins to build eastward over California. By Saturday highs will warm into the 70s near the coast and into the lower 80s inland. Saturday`s highs will be as much as 15-20 degrees warmer than today. A shortwave trough moving over the top of the ridge over the weekend may stall the warming trend on Sunday, but then renewed warming is anticipated as we move through the first half of next week. && of 5:49 PM PDT Wednesday...A robust influx of moisture compared to April climatology will continue to interact with a surface cool front located off northwestern California. This front will accelerate to approx 30-40 mph moving southeastward across the Bay Area and north Central Coast this evening and tonight; additional pockets of light rain or drizzle are quite likely up until frontal passage. Preceding this front nearly saturated air up to approx 7 thousand feet is causing IFR cigs to develop with spill-over of IFR now extending eastward across the San Francisco Peninsula. Based on the WRF model IFR will quite likely continue to spread into the East Bay and South Bay through this evening with lowering confidence as to if and when cigs/vsbys may lift later in the forecast period. This incoming change of air mass following the cold front is very shallow based, the NAM shows cooling at 925 mb not beginning until Thursday morning thus the caveat here is it could be slow clearing tonight into Thursday morning specifically along the immediate coastline and nearest the bays. KMUX is mostly if not entirely echo-free at the moment due to the shallow based nature of this present weather pattern. Vicinity of KSFO...IFR cig persisting this evening, possibly seeing a return to MVFR cigs beginning 06z though timing is low to very low confidence. If W-NW winds happen to increase with gusts up to 20-25 knots as forecast mixing may help lift cigs somewhat. WRF model leans toward a gradual reduction in humidity, but not until much later tonight into Thursday morning. Coordinated with CWSU office. SFO Bridge Approach...San Mateo Bridge reports BKN cig as low as 1,300 feet, similarly plenty of saturated air will continue to reach into the approach this evening. Monterey Bay Terminals...MVFR lowering to IFR as similar to the Bay Area greater amounts of moisture will consolidate this evening prior to the arrival of a cool front. Off/on showers or drizzle tonight. Clearing Thursday with MVFR/VFR probably returning mid-late morning. && of 4:52 PM PDT Wednesday...Northerly flow will increase across the entire region tonight and Thursday as high pressure builds. The stronger winds will result in steep wind waves and fresh swell. These hazardous conditions will persist into the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 AM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM SCA...Pt Arena to Pt Reyes 0-10 nm from 9 PM SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 PM SCA...Pt Arena to Pigeon Pt 10-60 nm from 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...SF Bay until 3 AM && $$ PUBLIC FORECAST: Dykema AVIATION: Canepa MARINE: MM Visit us at Follow us on Facebook, twitter, and youtube at:
Area Forecast Discussion
National Weather Service Omaha/Valley NE
634 PM CDT Wed Apr 26 2017 .SHORT TERM...(Tonight through Saturday) Issued at 329 PM CDT Wed Apr 26 2017 The chance for freezing temperatures and frost tonight, then rain moving back into the area Thursday night through Saturday, are the primary forecast concerns. Temperatures this afternoon have struggled to gain much from morning lows, with readings at mid afternoon still in the upper 30s in northeast Nebraska, to the upper 40s in southeast Nebraska. Widespread cloud cover and cool northwest breezes made the chilly temperatures feel even colder. Back edge of cloud cover extended from central South Dakota into central Nebraska, close to mid level trough axis noted on water vapor imagery and RAP analysis. That trough is forecast to swing northeast of eastern Nebraska and western Iowa this evening. Subsidence in wake of trough should help to dissipate cloud cover. At the surface, strong low pressure is expected to move into the northern Great Lakes region by Thursday morning, with high pressure ridge extending from the western Dakotas into central Nebraska. Decreasing winds are expected in our area under this scenario, however calm winds promoting better frost formation environment is in question. However with temperatures already cool this afternoon, continued cold advection this evening, clearing skis and diminishing winds, frost formation is still possible where winds drop off significantly. Already have Frost Advisory going for the southern half of our area where collaboration with agricultural partners suggests plants are vulnerable, and see no reason to pull that advisory now. Farther north where widespread agricultural interests indicate current plant stages suggest little vulnerability to frost and high vulnerability to freezing temperatures, have opted to maintain our current Freeze Warning. Expect temperatures there to drop into the upper 20s in many spots, and remain there for several hours overnight. Low to mid 30s are forecast farther south. Overall flow pattern will favor a broad trough over the middle of the country into Friday, then sharpen into the Four Corners region into Saturday. Impulses rotating through that flow will bring chances for showers to the area off and on beginning Thursday night. Dry surface air on northeast low level flow should hold precip off until the evening, so much of Thursday should have at least some sunshine before higher clouds begin to thicken later in the day. Mid level impulse only slowly lifts through the area Friday morning, bringing a break in precip potential during the afternoon. The next shortwave is forecast into the Southern Plains Friday evening, which spreads northeast through Saturday. Models have trended farther south with this feature and associated precipitation through Saturday, focusing majority of activity well to our south. However southeast Nebraska into southwest Iowa will still be in the likely area of rainfall, with decreasing likelihood to only a slight chance in northeast Nebraska. Total rainfall through Saturday is forecast from a tenth in our north to about three-quarters of an inch in the south. .LONG TERM...(Saturday night through Wednesday) Issued at 329 PM CDT Wed Apr 26 2017 Mean mid level trough remains over the middle of the country through the middle of next week, with a more significant low moving into our region on Sunday. That low, originating from the Four Corners region, is forecast into northeast Kansas by Sunday afternoon, then on into the northern Great Lakes by Monday afternoon. Continued feed of moisture from the Southern Plains north into the middle Mississippi and Missouri River Valley regions will promote continued precipitation chances until wrap-around section of upper low lifts northeast of our area on Monday. So will have increased precipitation chances for all of eastern Nebraska and southwest Iowa Saturday night through Sunday night before decreasing Monday. Precipitation phase is a question, especially for northeast Nebraska, and generally for the morning hours of Sunday and Monday. A continued feed of colder air from the north will drive temperatures into the 30s for lows, and 850 temperatures are well below zero for the duration of the precipitation in northeast Nebraska, and for a time over the rest of our area. Thickness progs are borderline for much of the period, save for Sunday night into Monday morning in northeast Nebraska. And both GFS and ECMWF are in agreement. So there is certainly a potential for accumulating snow in northeast Nebraska if we can manage a full conversion to snow for a few hours and rates can overcome warmer ground temperatures. But with those things still in question now, have maintained our mention of a rain and snow mix where and when temperatures are forecast to drop to the middle 30s and below. Beyond Monday, slightly warmer temperatures, highs in the 60s, are forecast into mid week as heights gradually rise. However another shortwave dropping into the region could provide another quick shot of rain either Tuesday or Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 610 PM CDT Wed Apr 26 2017 Regional obs showing MVFR cigs across ern NE this evening. However...expect improvement to VFR at all terminals toward midnight tonight as back edge of cigs shifts east. VFR prevailing then thru the remainder of the fcst pd. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Frost Advisory from midnight tonight to 9 AM CDT Thursday for NEZ044-045-051>053-065>068-078-088>093. Freeze Warning from midnight tonight to 9 AM CDT Thursday for NEZ011-012-015>018-030>034-042-043-050. IA...Frost Advisory from midnight tonight to 9 AM CDT Thursday for IAZ055-056-069-079-080-090-091. Freeze Warning from midnight tonight to 9 AM CDT Thursday for IAZ043. && $$ SHORT TERM...Dergan LONG TERM...Dergan AVIATION...DEE
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
744 PM EDT Wed Apr 26 2017 .UPDATE... Inherited forecast is on track. Only minor adjustments have been made to the forecast in terms of the winds and temperature curve overnight. 23Z water vapor and H4 RAP analysis showing a benign and seasonable weather pattern in place over the eastern Gulf of Mexico and Florida peninsula. Significant trough/shortwave energy currently ejecting out of the central Plains into the Ohio/TN/Lower MS valleys...will de-amplify and shift east and northeast through upper ridging over the eastern seaboard prevents this system from every threatening our region. The associated cold front will simply run out of gas as it reaches the FL panhandle...and all synoptic forcing for showers will shift far to our north through the day. Thereafter as we head into Friday and the upcoming weekend, the synoptic pattern aloft and at the surface takes on a real summer-like look. The sensible weather will take on a real summer-like feel. Still a bit early in the season in terms of thunderstorms, with sea surface temps still a few degrees too cool, and plenty of hostile air aloft in terms of thermodynamics, would anticipate the forecast to remain mostly dry through at least Sunday. Can a very isolated shower pop up on the sea-breeze one of these afternoon? Sure, its possible, but the chances of any spot seeing rain are extremely remote. The real story Thursday through the weekend will be the very warm temperatures. Many locations away from the immediate coast will have good chances at reaching 90, with inland locations almost certainly surpassing 90. Even the beaches are going to see temperatures well into the 80s before afternoon sea-breeze flow knocks there temps back down toward the lower 80s. Have a great evening everyone and stay cool in the days to come. && .AVIATION... Basically looking at VFR condition prevailing for the duration of the TAF period. Only exceptions could be at KLAL/KPGD where a brief period of shallow field fog is possible in the hour or two surrounding sunrise, however, no significant vis restrictions are anticipated. Any field fog burns off quickly in the AM, leading to benign aviation conditions for the remainder of the day. Light SE winds early in the AM will increase to between 10-15 knots and transition south and then SW during the afternoon. && .Prev Discussion... /issued 321 PM EDT Wed Apr 26 2017/ SHORT TERM (Tonight-Thursday)... Mid/upper level shortwave trough will swing through the Mississippi and Ohio Valleys moving by to the north of the region with its associated cold front weakening and dissipating before it reaches the forecast area. The mid/upper level dynamics will remain well to the north of the area and with limited moisture not expecting any precipitation. What we will see however is an increase temperatures and humidity as the southeast to south flow continues around surface high pressure ridging west from well out in the Atlantic Ocean with a shift to southwest near the coast as the sea breeze develops Thursday afternoon. The increase in low level moisture along with the mostly clear skies could lead to some patchy fog over inland areas late tonight. Otherwise temperatures will be above normal with lows in the mid 60s to around 70 tonight and climbing into the mid 80s coast to the lower 90s inland Thursday. MID TERM/LONG TERM (Thursday Night - Wednesday)... An upper level low sits over northern Minnesota with broad troughing extending over the western half of the U.S. Upper level ridging continues to hold over the Florida peninsula into the long term period. The troughing over the western U.S. will further deepen by Saturday as a closed upper low moves southeast and will be located over the four corners region. As the trough out west deepens, the ridge over the southeast U.S. will strengthen and build northeastward toward Bermuda. The pattern shifts east by the beginning of next week with the closed upper low now located over the Great Lakes region and the upper ridge moving east into the western Atlantic. The upper low moves northeast by midweek and a quasi-zonal flow sets up over Florida. On the surface, an area of low pressure over Ontario extends a cold front southward along the east coast. This front dissipates over northern Florida as high pressure continues to ridge across the peninsula through the end of the week and into the weekend. This will keep a southeast through southwest wind flow over the area which will result in above average temperatures with the inland counties seeing daytime highs in the 90`s. Rain free conditions will also continue through Sunday. An area of low pressure develops over Missouri on Sunday and extends a cold front south through Louisiana and eastern Texas. This system tracks east and will bring increasing rain chances (30-50 POPs) to Florida on Monday and Tuesday. MARINE... Southeast to south flow will persist into early next week with a shift to southwest near the coast each afternoon. Winds will generally remain around 15 knots or less with seas 3 feet or less. Winds could reach exercise caution criteria late tonight and early Thursday morning across the northern waters for a short period and then across the offshore waters Saturday night and Sunday night. FIRE WEATHER... Relative humidity values are expected to dip into the middle and upper 30s each afternoon through the weekend, but critical durations are not expected and sustained winds should remain less than 15 mph. Therefore, no red flag conditions are anticipated. && .Preliminary Point Temps/PoPs... TPA 73 88 73 90 / 0 0 0 10 FMY 69 91 72 92 / 0 0 0 10 GIF 67 93 71 95 / 0 0 0 20 SRQ 70 86 71 86 / 0 0 0 10 BKV 63 91 66 93 / 0 0 0 20 SPG 71 86 74 89 / 0 0 0 10 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION/MARINE...Mroczka Previous Discussion...Close/Wynn
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
845 PM MDT Wed Apr 26 2017 .UPDATE... Issued at 844 PM MDT Wed Apr 26 2017 Fairly quiet evening in store across the region as mid/high clouds have dissipated...and low cloud shield has slowly shrunk over time. Am a bit concerned that with snow melt this afternoon and fcst models showing light low level winds...that there might be some shallow ground fog setting up. Fcst soundings from the HRRR and NAM12 lean toward that possibility. Not sure that it is worth mentioning in the grids...but did make a mention in the TAFs. && .DISCUSSION...(This Evening Through Wednesday) Issued at 337 PM MDT Wed Apr 26 2017 Current surface analysis shows weak high pressure nosing south out of central Canada and into the Dakotas. Low pressure is located across southern BC, with cold front stretching across the Pacific NW. Upper level analysis shows weakening low moving northeast away from the Dakotas, with cutoff low over southwest Canada. Strong jet in place from the Pacific NW to the Southern Plains, with developing shortwave sliding east-southeast across eastern portions of OR and WA. Clouds have been very slow to dissipate across our area today, especially from west central to south central SD. Skies are variably cloudy in most places with very cool temps, mid 30s to mid 40s. Some showers have developed south of our northeast WY zones, moving eastward. A few light showers could clip far southern Campbell County through early evening. The next system will begin to impact the area on Thursday, with chances for showers increasing across northeast WY into southwest SD, especially by the afternoon. Most of the pcpn should be in the form of rain during the day as slightly milder air pushes in. Highs will be in the 40s and lower 50s, warmest over eastern areas where there will be more sun. Medium range models still showing differences on track of the system as it slides down the east slopes of the Rockies and how far east pcpn will reach into our CWA. Latest GFS and NAM further east with more significant pcpn compared to EC. A general blend seems appropriate at this point. For Thursday night, pcpn will expand a bit further east across the area Thursday night, with the more significant pcpn moving across southern portions of northeast WY and possibly into far southwest SD. Rain will change over to snow overnight across northeast WY and into the Black Hills, and likely across far southwest SD toward daybreak Friday. This system is not quite as cold as the last one, so snow can be expected across these areas in the morning, with a mix or change over to rain in the afternoon in many areas. Snowfall amounts look to be on the lighter side in most areas, up to a few inches from the Black Hills to far southwest SD and most of northeast WY. However, across southern Campbell County where the heaviest pcpn is forecast, amounts approaching 6 inches are possible, especially the higher elevations of southwest Campbell County Thursday night into Friday. Pcpn will dissipate and shift south of the area Friday night as system moves into the Central Plains. The weekend looks mainly dry, but remaining cool, as large trough lingers over the region. Will see temperatures possibly approaching average early next week, but unsettled weather will return for at least the first half of the week. Active northwest flow on the back side of the trough will bring several disturbances across the area, with daily chances for showers in most areas. The bulk of the activity should come during the afternoon and evening hours. && .AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening) Issued At 605 PM MDT Wed Apr 26 2017 MVFR cigs have become SCT over the last hour as diurnal heating begins to wane over the KRAP terminal. Additionally, expect winds to diminish to less than 10kts for both KGCC and KRAP with FEW/SCT sky conds. Fcst soundings show potential for some light fog to develop...especially with the melting that occurred today in the KRAP have inserted brief mention for both locations. Otherwise look for an increase in cloud cover ahead of next system during the day Thursday. Inserted some pops for light rain chances in the KGCC terminal toward the end of the valid period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ Update...Hintz DISCUSSION...26 AVIATION...Hintz