Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/11/17

Area Forecast Discussion
National Weather Service Gaylord MI
1145 PM EDT Sat Jun 10 2017 .UPDATE... Issued at 1025 PM EDT Sat Jun 10 2017 Tight low level pressure gradient over the Northern Great Lakes region continues to result in gusty S/SW winds across our entire CWA late this evening. Winds are beginning to slowly diminish thanks to loss of diurnal component to low level mixing. This diminishing trend will continue as we head into the overnight hours as the upstream weak front reaches our CWA. Narrow line of convection continues to fire along this boundary aligned with a narrow axis of instability and 850 mb theta E ridging. Latest NAM does not appear to be handling this convection well...while the latest RAP and HRRR have both caught on to this activity. RAP carries some weakening convection into our CWA late tonight... while the HRRR shows this convection coming to an end before reaching our CWA overnight. Will adjust timing of convection into our CWA overnight based on latest radar and model trends...and will diminish POPs given the HRRR tendency to kill convection before it reaches our area. && .NEAR TERM...(Tonight through Sunday) Issued at 337 PM EDT Sat Jun 10 2017 ...Stickier with increasing shower/t-storm chances... High impact weather potential...thunderstorm chances tonight, especially late, and again midday thru Sunday afternoon. Marginal svr threat. Unseasonably deep (985mb) surface low is in far western Ontario, ne of Winnipeg. Tight pressure gradient in the warm sector is driving warmer air into the region on gusty s to sw winds. Temps are pushing up to 90f in some areas. Some cirrus overhead, especially in eastern upper. But the sky is almost entirely largely devoid of cu, so needless to say there are no showers out there (except near Whitefish Bay). Precip trends are the primary concern. Ongoing headlines (wind/fire wx/beach hazards) will remain up thru early evening as planned. Tonight...surface low will move quickly ene and deepen a bit further, crossing southern James Bay on the way of northern Quebec. Associated cold front will cross western/northern Superior, but remain upstream of this forecast area. Low level jet remains intact for the 1st half of the night, before weakening/veering occur after 06z. However, the west is where the instability axis is found, and as that folds into the region overnight, precip chances will be increasing. Pretty strong signals from multiple RAP runs that elevated convection will develop in parts of northern lower MI shortly after midnight. Activity is most likely to initiate near Beaver Isl, expanding/developing south with time. Will be boosting pops considerably tonight, especially in northern lower MI after 05z. Will refrain from taking things into likely territory just yet. Though an instability plume will fold in, its not terribly impressive (perhaps reaching 1k j/kg of mucape). Broader shear environment will become less impressive as the low level jet weakens (0-6km bulk shear 30-40kt). And convection will clearly be elevated. Need to monitor if something very well-organized can take a run at us from the wnw, but otherwise deep convection may approach, but likely not reach, svr levels. A warm night, with sw winds for most of it and surface dew points on the rise. Min temps near 60f in much of eastern upper, in the 60s in northern lower. Sunday...any leftover convection should quickly decay in the morning. Associated cloud cover will linger a lot longer though, with nocturnal activity contributing to moistening the airmass thru a deep layer. Cold front lays out just to our north, while pressure falls occur in the upper MS Valley, resulting in a developing warm front poking into nw lower MI. This presages another push of rich 850mb theta-e air into the region. And as a result, pops will be on the increase again, perhaps as soon as midday. Those pops will increase further and expand northward as the afternoon proceeds. We look to have enough cloud cover to limit instability to some degree. Some pockets of better heating are likely, and a localized svr threat may emerge as a result (ne lower near Saginaw Bay perhaps the best shot?). However, best instability (south) and best shear (north) will be separated from each other. Svr environment looking increasingly charged w of Lake MI tomorrow, but not so impressive here, at least for now. Max temps hindered somewhat by cloud cover, mainly upper 70s to mid 80s. A few upper 80s possible in the far se. && .SHORT TERM...(Sunday night through Tuesday) Issued at 337 PM EDT Sat Jun 10 2017 ...Thunderstorms Sunday Night possibly Severe... High Impact Weather Potential...Marginal severe risk Sunday night. Pattern Synopsis/Forecast...Flat 500 mb ridge with convergence over Lake Superior and the UP, will be the main focus on what looks to be MCS development from Sunday afternoon over Minnesota and Wisconsin. The models aren`t exactly in alignment with the scenario as the ECMWF puts convection into N Lower during the day on Sunday and lingers into Sunday evening. While the GFS puts showers over the region that linger a bit in N lower, while shifting the focus to E Upper. After 06z, another piece of energy pushes into NW Ontario forcing some troughing into W Upper which then pushes into NW Lower. Thunderstorm activity lines up on a the sfc trough and weak cold front overnight. Monday morning, the front is stretched out over the region, but the shortwave trough that caused the ridge to buckle a bit, moves east and the ridge rebounds. This leads to maybe some showers initially over N Lower. However, for Monday afternoon, the front that is stationary gets moisture and heat pumped into it, and the RRQ of the 50-60 knot 500 mb jet streak to get things energized over N lower. Primary Forecast Concerns...With the flat, fast flow, any ripple in the 500 mb flow could produce showers and thunderstorms. If the models are wrong on the strength of a speed max, it could be more or less than advertised now. At this point the chance pops characterizes the confidence in the convection. This is going to be a "wait and see" type of situation as until we see the convection form and how it affects the 500 mb/sfc frontal pattern. .LONG TERM...(Tuesday night through Saturday) Issued at 337 PM EDT Sat Jun 10 2017 High impact weather potential...Thunderstorms possible at times through Thursday. Active weather is expected through mid-week as an H5 cutoff low and attendant surface low lift through the Dakotas, continuing through Hudson Bay late in the week. Wednesday and Thursday continue to look the most favorable for storm development as we sit in the warm sector. Storm activity will be suppressed once the cold front comes through, which right now looks to be late Thursday as the surface low pushes into Hudson Bay. Temperatures will run above normal through the period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 1145 PM EDT Sat Jun 10 2017 Windy surface conditions and LLWS will persist into the overnight hours...but will begin to diminish as we head toward daybreak in response to a loosening of the low level pressure gradient. Mainly clear skies will give way to increasing low level clouds overnight into Sunday as low level moisture quickly increases ahead of the approaching low. Chances of showers and thunderstorms will also increase overnight into Sunday...with the best chances initially across NW Lower Michigan (PLN/TVC/MBL). && .MARINE... Issued at 337 PM EDT Sat Jun 10 2017 Unseasonably strong low pressure nw of Superior will move quickly ene-ward thru tonight. Strong sw winds will continue thru this evening, diminishing overnight. Gales/small craft advisories will continue. Southerly winds will increase again Sunday night, though not as to the degree as today. && .APX WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT until 6 AM EDT Sunday for MIZ015-020-025- 031. LH...SMALL CRAFT ADVISORY until 6 AM EDT Sunday for LHZ345>349. LM...GALE WARNING until 6 AM EDT Sunday for LMZ341-342-344>346. SMALL CRAFT ADVISORY until 6 AM EDT Sunday for LMZ323. LS...GALE WARNING until 6 AM EDT Sunday for LSZ321-322. && $$ UPDATE...MLR NEAR TERM...JZ SHORT TERM...JSL LONG TERM...ALM AVIATION...MLR MARINE...JZ
Area Forecast Discussion
National Weather Service Denver/Boulder CO
855 PM MDT Sat Jun 10 2017 .UPDATE... Issued at 855 PM MDT Sat Jun 10 2017 Only minor updates to the winds this evening and overnight as a strong mesoscale low deepened across the Denver metro area this afternoon and wobbled a bit through this evening before filling given the loss of daytime heating. East and southeast winds to the north of the cyclone across the northern Plains of Colorado should weaken by midnight as the pressure gradient relaxes. West of the cyclone west winds should exist roughly from just east of Denver into the mountains and foothills. New wind grids reflect this. Something to watch for Sunday afternoon is that both the RAP and NAM generate a good amount of instability (MUCAPE ~1500 J/kg, MLCAPE ~900 J/kg) across the I-25 metro corridor, along with some convective precipitation along the northern foothills and adjacent Plains. Model soundings look too wet so at this time will not increase PoPs. The models assume surface dewpoints in the low to mid 40s Sunday afternoon along I-25. Seems quite overdone given current observations and HRRR trends for tomorrow. Regardless, cloud cover should be greater Sunday compared to Saturday and keep temps cooler most areas other than the far NE Plains. && .SHORT TERM...(This evening through Sunday) Issued at 352 PM MDT Sat Jun 10 2017 The cold front that is pushing south and west across the plains has slowed down considerably early this afternoon. Temperatures behind the front are in the 85 to 90 F range with 45 to 50 F dew points. South and west of the front, readings are in the mid 90s F with dew points in the upper 20s to mid 30s F. The easterly winds are pretty brisk as well behind the front. Models have southwesterly flow aloft for the CWA tonight and Sunday. There is benign synoptic scale energy for the CWA tonight and Sunday. The low level pressure and wind fields have a drainage/downsloping combination overnight, then more easterlies on Sunday. For moisture, it is pretty dry overnight, with some over the mountains and foothills by Sunday afternoon. The precipitable water values are in the the 0.25 inch west to 0.75 inch northeast range tonight and Sunday. Low level dew point readings are in the 20s to 30S F for much of the CWA, with 50S F over the northeastern quarter over the CWA. There is no measurable rainfall for the CWA tonight and Sunday morning, then a tad on the ECMWF and GFS Sunday afternoon. There is a pretty decent cap in place on the lapse rates fields in the mid levels this evening and again Sunday afternoon. It is awfully warm aloft. No pops. For temperatures, Sunday`s highs look to be 1-4 C cooler than this afternoon`s. .LONG TERM...(Sunday night through Saturday) Issued at 230 PM MDT Sat Jun 10 2017 The atypical deep closed upper low spiraling over the central Great Basin as of 12z/Monday is progged by the GFS, ECMWF, NAM, Canadian and UKMet to track northeast and be over southern Idaho/northwest Wyoming by Monday evening. This places Colorado under an abnormally strong, very warm and dry southwest flow aloft. Concurrently, models indicate strong pressure falls along the lee of the Front Range south of a deep surface low which models show forming near Fort Collins. As a result should see strong and gusty south-southwest winds for the high mountain parks, particularly Middle and South Parks, the Front Range mountains, in the foothills roughly south of I-70, and on the plains generally along and south of I-76. Could see peak gusts anywhere from 45-55kts on the higher mtn ridges, and from 32-38kts on the mtn valley floors, southern foothills, Palmer Divide and nearby plains. If if were not for the wet/green fuels out there, the wildland fire danger would be much higher with the anticipated gusty winds, low RH and very warm temperatures. As it stands, do not plan to hoist a fire weather watch, but will stress the hot and gusty conditions in the Fireweather forecast synopsis. By late afternoon Monday, with the upper low passing to our northwest, and the sfc low lifting into the Nebraska panhandle, a number of the models indicate patchy light QPF from isolated t-storms over the northern Front Range. At the same time, the gusty winds on the plains spread north to the Wyoming line and remain gusty til mid- evening. Overnight, winds shift to westerly with cyclogenesis in the Nebraska panhandle and with a cold front slipping south, winds shift to nwly and usher in cooler air. Expect to see 10-14 deg F cool down in max temps. Tuesday-Wednesday...the upper trough, somewhat weaker at this point, slips north of Colorado. The cool down on Tuesday should moderate some on Wednesday with a return to a west-southwest deep layer flow. Could see a few instability showers/t-storms over the high terrain both afternoons, and really nothing to speak of on the plains. Thursday into Friday...the upper trough moves shift of the region and an upper ridge begins building slowly over the Great Basin. Warmup will be gradual and precip chances essentially nil both days. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 855 PM MDT Sat Jun 10 2017 VFR conditions with no precipitation expected through Sunday evening at all three TAF sites. Winds will be the main forecast issue. A multitude of surface boundaries approached or crossed the KDEN airfield this afternoon and early evening, associated with a mesoscale cyclone that developed along the frontal boundary from midday today. Strong heating with temps in the 90s deepened the cyclone late afternoon across the southwest part of metro Denver. With the loss of heating the cyclone has filled significantly and the pressure gradient has relaxed. Currently the low is just northeast of KDEN resulting in west and southwest winds across the airfield. Expect those winds to continue much of the night but with speeds 10 kt or less tonight not expecting any impacts. At APA and BJC wind have also come come quite a bit and will remain that way tonight, generally out of the WNW at BJC and SW at APA. On Sunday diurnal east winds 8-12 kts should kick in at the TAF sites after 16Z and continue throughout the afternoon and evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...RJK LONG TERM...Baker AVIATION...Schlatter
Area Forecast Discussion
National Weather Service State College PA
1001 PM EDT Sat Jun 10 2017 .SYNOPSIS... Summer heat and humidity will build over central PA through early next week. A modest cooling trend is expected during the second half of the upcoming week accompanied by an increasing risk for showers and thunderstorms. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Flat upper ridge building through central and eastern GLAKS tonight with mainly thin cirrus traversing the region overnight. Dry and warm conditions will prevail along with the mostly clear skies, and min temps will range from the upper 50s to low 60s in most areas. Some patches of fog are expected around daybreak mainly over the lower Susquehanna Valley where winds/dewpoints should be lightest/highest. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday will be very warm with plenty of sunshine with max temps in the mid 80s to around 90F. Dewpoints creeping into the low 60s will result in max heat index values in the low 90s over much of the Susquehanna Valley. Another mainly clear and warm night with mins 60-65F. && .LONG TERM /MONDAY THROUGH SATURDAY/... The medium range will feature below normal heights over the western US and above normal heights over the east, through about the middle of next week when the pattern becomes more zonal but with the 500mb heights remaining above 5800dm through the end of the week. This will equate to an extended period of summer-like warmth with dewpoints well up into the range where most will feel uncomfortable. The warmest temperatures will be early in the period through midweek, with heat indices in the 90s being common over much of the central and eastern zones (and even approaching 100F in parts of Susq Valley). Air conditioner weather. Precip chances will remain low under the ridge until a weak back door cool front approaches from the north and brings a chance for showers and thunderstorms Tuesday. I kept chances low given good model agreement that we will remain rather warm in the mid levels through the day Tuesday, despite heat and humidity making for robust model CAPES. Slightly colder temps aloft bring best chance for showers/tstms to the NE counties. A better chance for showers/storms will present itself for Wednesday as the same front lifts back across the area as a warm front. Humidity throughout the eastern US will be on the rise as a southerly flow establishes on the west side of the high pressure that will set up along or just off the east coast. This will lead to a very familiar summer-type forecast of hazy- warm and humid conditions with the chances for mainly diurnal showers and thunderstorms. The increasing cloud cover and chances for precip toward the end of the extended will knock a few degrees off daytime highs, but overall temperatures will average above normal for the next week. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... High pressure building along the east coast will bring with it a high confidence in widespread VFR conditions through Sunday. Clear skies and light winds may result in patchy fog around daybreak Sunday across eastern Pa, but coverage will be limited. A blend of latest HREFV2, LAMP, downscaled NAM and HRRR suggests about a 25 pct chance of a brief vis reduction at IPT and even less chance elsewhere. .OUTLOOK... Mon...No sig wx expected. Tue...Scattered PM tsra impacts possible, mainly north. Wed...Scattered PM tsra impacts possible, mainly south. Thu...No sig wx expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Steinbugl NEAR TERM...DeVoir/Steinbugl SHORT TERM...Steinbugl LONG TERM...RXR AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Dodge City KS
610 PM CDT Sat Jun 10 2017 ...Updated aviation discussion... .SHORT TERM...(This evening through Sunday) Issued at 224 PM CDT Sat Jun 10 2017 RAP today had some 0-1km moisture convergence at 21z Saturday and 00z Sunday along the dry line which will be located near Garden and Liberal with good mid level instability in place. Shear around 20 knots, high LCL, and large DCAPE was forecast also so if storms can overcome the warm mid level temperatures these storms could produce some gusty winds early this evening. Currently however am unsure if anything will develop this evening given the warm temperatures forecast in the 750 to 600mb level late day. RUC suggests to erode this cap then temperatures need to be approaching 104. Will wait and see but think the cap will hold. Sunday will be a similar story when it comes to precipitation chances for western Kansas. 0-1km moisture convergence improves by 21z Sunday as mid level instability improves to greater than 1500j/kg. NAM and GFS model soundings continue to indicate a small amount of cin present late day as an upper way forecast to cross the Western High Plains. CIN appears slightly stronger than today but not by much. Could once again have a few isolated storms but at this time will be continuing to keep the forecast dry at this time. Given the 850mb to 700mb temperature trends from 00z Sunday to 00z Monday it will be another day with temperatures +100 west of the dry line. East of the day line highs will be mainly in the middle 90s. .LONG TERM...(Sunday night through Saturday) Issued at 224 PM CDT Sat Jun 10 2017 Based on 850mb temperature trends early next week the heat will continue through at least Monday with highs once again approaching 100 west of the dry line which will still be located over western Kansas. Another subtle wave is forecast to precede the main upper level system Monday night and will have to wait and see if any storm may be able to break the elevated warm layer over western Kansas. At this time will continue to follow the dry forecast. The better chance for convection along the dry line and possibly along an approaching cool front will be late Tuesday as a stronger upper level system moves out into the Western High Plains. The better forcing, moisture, and instability will be along the dry line so focused the better chances for convection here. Ahead of this approaching cold front it will be another hot day although 850mb temperatures at 18z Tuesday and 00z Wednesday were a couple of degrees cooler compared to those at 00z Tuesday. On Tuesday there will also be a chance for severe weather along and ahead of this dry line with large hail and damaging wind gust being the main hazard Tuesday evening. Exactly where this boundary will be is still unclear given that this is still several days out so will favor staying with the latest models for now. These models placed the dry line and the better chances for these severe storms near and east of highway 283. As the upper low lifts northeast into the northern Rockies towards mid week and westerly down slope flow is expected to develop across the Central Plains. Given this set up am unsure how far south this cold front will move on Tuesday before stalling out. Also do not think much of a cool down will occur mid week with this frontal boundary should if move into southwest Kansas. The chance for scattered thunderstorms will improve late week near and north of this surface boundary as at least two upper level waves embedded in the west to northwesterly flow crosses the Western High Plains late Thursday and late Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 610 PM CDT Sat Jun 10 2017 A strong low level jet is expected to develop after sunset and continue through the night over the southwest Kansas terminals. This will also keep surface winds gusty at times overnight. Otherwise, VFR conditions are expected to prevail. && .PRELIMINARY POINT TEMPS/POPS... DDC 70 96 70 98 / 0 10 0 10 GCK 70 103 68 100 / 10 10 0 10 EHA 67 102 64 98 / 0 10 0 10 LBL 70 103 68 100 / 10 10 0 10 HYS 72 99 72 98 / 0 0 0 0 P28 71 93 72 95 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Burgert LONG TERM...Burgert AVIATION...Gerard
Area Forecast Discussion
National Weather Service Duluth MN
701 PM CDT Sat Jun 10 2017 .UPDATE... Issued at 700 PM CDT Sat Jun 10 2017 The surface front stretched through the tip of the Arrowhead to Ashland to just east of Siren and south. There has been some deeper convection over the Arrowhead to the Apostle Islands but not much further south. It`s still possible a strong to severe storm could develop ahead of the front over northwest Wisconsin through about 03Z. The wind has diminished over northwest Wisconsin and the Wind Advisory has been cancelled. && .SHORT TERM...(This evening through tonight) Issued at 310 PM CDT Sat Jun 10 2017 The focus remains on the threat of severe weather associated with the passage of a cold front today. It still looks like storm development will most likely hold off until the late afternoon or early evening, when the cold front is entering the Arrowhead and northwest Wisconsin. There is increasing confidence in the severe weather potential for the storms do develop in northwest Wisconsin. The Storm Prediction Center increased the risk of severe weather to a slight risk, over areas of northwest Wisconsin generally along and east of a line from Bayfield, to Hayward, to Shell Lake. The Northland had a blast of hot air amid gusty south-southwest flow today. This flow was ahead of an approaching cold front from the west. Temperatures, as of the middle of the afternoon, had climbed well into the 80s and even some low 90s. Low-level mixing and strong flow in the mixing layer was causing widespread wind gusts of 25 to 40 mph east of the cold front. Some areas of northwest Wisconsin had gusts to around 45 mph, and there had been reports of fallen trees and power lines, which had sparked some fires. Dew point temperatures had increased to the middle 60s. It could be described as the Northland`s hottest day of the year thus far. The cold front, which was associated with an area of low pressure in far northwest Ontario, stretched south through north- central and central Minnesota. Gusty and drier westerly flow was following up the cold front. A 120 knot upper-level jet streak was over southern Manitoba and far northwest Ontario, with fairly strong west-southwest flow across the Northland. This cold front will continue shifting east through the Northland this evening, and is expected to exit the southeastern forecast area before midnight. The warm and humid airmass will continue to build up MUCAPE ahead of the cold front, but capping and the lack of large-scale forcing will make it difficult to get thunderstorm development along the cold front until later in the day. The one exception may be up near the international border area, from northern St. Louis County into the Boundary Waters. There has been some erosion of the capping, and weak storms had already developed north of the Canadian border. Some storms might develop across into the Minnesota side of the border as the cold front moves east. There will be some modest large-scale forcing when the front enters northwest Wisconsin and the eastern Arrowhead very late this afternoon and this evening. The extra support to trigger storms will cause ramp up the chances of chances around that time for those areas of northwest Wisconsin. Severe weather is certainly possible at that time. The storms will be developing in an area of ample instability and strong deep layer wind shear, especially areas of northwest Wisconsin near and east of a line from about Bayfield, to Hayward, and Shell Lake. There will likely be about 1500 to 2500 J/kg of mixed layer CAPE and about 45 to 55 knots of 0-6 km bulk wind shear. This environment will be conducive for the development discreet supercells during the initial stages of convection. Strong updrafts could produce tall storms capable of producing large hail, perhaps up to the size of golf balls, despite the high freezing levels around 15000 feet above ground level. Strong flow in the mixing layer and aloft will boost the threat of damaging wind gusts with these storms. Precipitable water values around 1.5 inches will support heavy rainfall rates. There is also a threat of tornadoes with these supercells, too, considering about 20 to 25 knots of 0-1 km bulk shear. The initial storms might transition into bows and line segments as the outflow from the storms helps trigger convection. This means the main threat of the severe weather might transition from discreet supercells with all kinds of severe weather, to more of a threat of damaging winds as the storms progress farther east in northern Wisconsin. While the previous paragraphs paint a picture of really bad weather for northwest Wisconsin today and this evening, there is a still the possibility there could be little if no development along the front as it moves through northwest Wisconsin. There are still some models downplaying convection, such as the NAM12, GFS, and European. The higher resolution models, though, like the HRRR and RAP, have consistently been developing storms over northwest Wisconsin for the last 6 hourly runs or so. The threat of storms should fully exit the far southeast corner of the forecast area, the Price County area, before midnight as the cold front exits the region. Drier air will filter into the Northland in the wake of the cold front, providing clear skies tonight. Very light wind speeds will develop. Fog chances will be very low, expect in some areas of northwest Wisconsin that get significant rain from storms this evening. That added soil moisture may be just enough to produce some fog. Overnight lows will be in the 50s. .LONG TERM...(Sunday through Saturday) Issued at 310 PM CDT Sat Jun 10 2017 A rather active pattern appears to be in place across the northern tier of states for much of the upcoming week, which should be supportive of several bouts of thunderstorms and the associated potential for severe weather. Chances for thunderstorms and associated severe weather/heavy rainfall potential are expected to be rapidly increasing from southwest to northeast on Sunday as a strong low level warm/moist advection pattern translates east-northeastward along a quasi- stationary frontal boundary that is expected to be located from eastern South Dakota to northwest Wisconsin. Rapid return of moisture and instability (CAPE >300 j/kg in the warm sector) driven by the low level jet underneath steep mid level lapse rates superimposed with >45 knots of deep layer shear seems to suggest a very favorable set up for severe weather on Sunday. The primary uncertainty at this time appears to be the timing, and to a lesser degree, convective mode. With that said, most of the latest model guidance (supported by operational experience) seems to be converging to an MCS emerging out of the eastern Dakotas sometime late tonight or Sunday morning, and then continuing to ride along and north of the surface-925 mb warm frontal zone along the nose of the low level jet and CAPE gradient into east central Minnesota and eventually northwest/north central Wisconsin. If this scenario plays out, the convective mode would support the primary threat being damaging winds, with a least some threat of moderate/high end damage potential given the degree of instability/shear and large scale support. The strength of the deep layer shear would also strongly support embedded supercellular elements, with an attendant risk of very large hail and perhaps a low risk of a few tornadoes and/or high end wind damage with the most highly organized parts of the MCS. As with any convection with this high if precipitable water availability, the risk of heavy rainfall and flooding will also be present. While large scale support does not appear overly favorable Monday- Tuesday, the DLH CWA will remain on the northern periphery of the CAPE axis over the plains, and underneath moderate to strong westerly flow aloft. As is often the case in June, with this set up, almost any weak disturbance translating eastward in the faster flow aloft will have the potential to produce thunderstorms. A better chance for organized, and once again strong to severe storms, seems likely somewhere in the region during the middle part of the week as another large scale trough moves into the northern plains and western Great Lakes region Tuesday night/Wednesday. This system appears as though it will be accompanied by very strong instability and sufficient shear for severe storms, but the exact location/timing/mode this far out, is of course, highly uncertain at this time. After the mid week system moves northeast, much of the northern plains/western Great Lakes will be underneath west-northwest flow aloft, with at least some instability present into next weekend. Initially, deep layer subsidence behind the mid week system may limit chances for thunderstorms, but at least some risk for additional storms is expected to persist into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 700 PM CDT Sat Jun 10 2017 A cold front stretched from the tip of the Arrowhead through Ashland to just east of Siren and south early this evening. Gusty westerly winds have developed behind the front with southwest winds ahead. There still may be some thunderstorms that form ahead of the front through about 03Z. VFR conditions are expected for most areas through the period with a couple exceptions. There may be patchy fog later tonight as winds diminish. Lower ceilings will also be possible across southern portions of the Northland on Sunday as more thunderstorms will be possible there. Thunderstorms are expected to develop over South Dakota later tonight and they will move east to northeast through the day Sunday. At this time, we think they will affect KBRD and KHYR and possibly KDLH. We included thunderstorms in the forecast there tomorrow but there will likely need to be some refinement to the timing. Heavy rain and a period of strong wind will be possible with the storms. && .PRELIMINARY POINT TEMPS/POPS... DLH 57 74 54 79 / 10 70 40 10 INL 52 79 53 79 / 0 10 20 0 BRD 57 76 57 83 / 20 70 20 10 HYR 58 82 60 84 / 40 70 70 20 ASX 59 78 56 79 / 30 70 70 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 9 PM CDT this evening for LSZ121- 140>148. && $$ UPDATE...Melde SHORT TERM...Grochocinski LONG TERM...Miller AVIATION...Melde
Area Forecast Discussion
National Weather Service Glasgow MT
907 PM MDT Sat Jun 10 2017 .SHORT TERM...for northeast Montana...tonight through Mon... Latest Update... A few tweaks were made to winds and overnight low temperatures. While occasional gusty winds may occur near showers, expect them to prevail at around 10 mph overnight. Otherwise the forecast remains in shape with showers gradually diminishing over the area. Much of this activity has been in the form of virga anyways, and dry weather conditions are expected into Sunday. Maliawco Previous Update... Pops were adjusted in the near term based on radar reflectivity observations and current trends. Much of this is likely virga though isolated to widely scattered showers are certainly possible this evening across portions of the CWA, mainly before dark. Otherwise the forecast remains on track. Maliawco Previous Update: Made a quick updated to end the lake wind advisory for Fort Peck Lake, as winds have decreased across the lake. Gilchrist Previous discussion: The short term starts out with generally pleasant conditions, albeit a bit windy across the region. Fair weather cumulus are spreading across the region as the airmass modestly destabilizes. While not expected to be widespread, some of the short term models, such as the HRRR and NAM, are producing some chances for precipitation in the south and southwest this evening. The source seems to be that the models are hinting at a small shortwave embedded in the general southwest flow. Combined with some signal of increasing potential instability due to increasing Theta-E values and some signal of mesoscale cyclonic vorticity advection within the shortwave, elevated showers will be possible in the southwest this evening. Tomorrow looks to generally be dry throughout the region, with continued westerly winds that are somewhat weaker than today, and minimum RH values generally similar to today. Thus, fire weather concerns do not currently look to necessitate any headlines during the short term. A closed upper-level low pressure system is expected to begin swinging up into Montana by near the end of the short term period. Ahead of the low, a weak frontal system, which could very well be the leading warm front of the larger cyclone, passes through the region and flips the winds to east to southeast throughout the region by Monday morning. As the low swings up from Nevada/Idaho, precipitation will spread up from the south and into the region early Monday in conjunction with the frontal passage. The bulk of the potential precipitation with the system, however, will be held off until the beginning of the extended period. Bigelbach .LONG TERM...Mon night through Sat... 12z models didn`t change things too much from the previous forecast. One thing that stands out is that severe thunderstorm chances seem slim. Also, models continue to trim rainfall amounts. The ECMWF was drier than the GFS. Since the models tend to overshoot the amounts during this period, think that the ECMWF is the better solution. Looks like amounts Monday Night and Tuesday will generally be from 0.33 in the southeast zones to 0.75" in the northwest. Main deviation from Forecaster Builder solution was to raise pops where qpf was GTE 0.25". Rest of forecast looked good. TFJ Previous Discussion... Upper low off the Pacific Northwest coast expected to rotate into the Great Basin over the weekend and then lift northeast across Montana during the early part of next week. The slow moving low pressure system has the potential to bring much needed significant precipitation to eastern Montana from Monday through Wednesday. Scattered showers and a few thunderstorms expected to develop Sunday night over southern Montana under the area of difluence ahead of the upper low. These showers will spread north during the day on Monday before organizing into a precipitation shield Monday night as the stacked low lifts toward Montana. Models in good agreement with the track and positioning of the low. More uncertainty centers on the impact of the dry slot as it pushes into the southeast corner of the state. Low lifts across the northern plains and into southern Manitoba Tuesday night and Wednesday with precipitation tapering off from the southwest. The rest of the week features nearly zonal flow across the northwest corner of the country. This will bring generally dry conditions and nearly normal temperatures with a slight warming trend. Ebert && .AVIATION... VFR. Mid-level clouds (AOA 8K FT AGL) will move in tonight from the southwest and linger into Sunday. Winds: West winds will quickly diminish by sunset and are expected to be lighter Sunday. Outlook: Rainshower chances increases Monday with IFR ceilings late Monday Night and Tuesday. TFJ && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Grand Rapids MI
1140 PM EDT Sat Jun 10 2017 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 314 PM EDT Sat Jun 10 2017 Most of the area will see dry conditions persist through Monday along with hot conditions. There will only be a slight chance of a shower or storm late tonight/Sunday and again late Monday/Monday night mainly across Central Lower Michigan. Better chances for rain will come for the second half of the week along with slightly cooler temperatures as a system slips down into the area. && .UPDATE... Issued at 1005 PM EDT Sat Jun 10 2017 The air mass remains very dry with Pwats only around 0.50. However very late tonight (after 4-5 am), much higher Pwats over 1.5 inches come into the area from the northwest. Latest HRRR guidance indicates that a band of moisture/instability in the 850-700 mb layer will impact areas like Ludington/Pentwater/Baldwin toward daybreak. Will therefore keep the chance pops going in the nrn CWFA very late tonight into Sunday morning, with a few isolated tstms possible since the 850-700 mb cape is shown to increase to 1000-1500 J/KG with the arrival of the higher axis of theta-e air from the northwest. && .SHORT TERM...(This evening through Monday night) Issued at 314 PM EDT Sat Jun 10 2017 Our main concern through the short term is pcpn chances from late tonight through the end of the period on Mon night. We are thinking that chances are fairly limited, and mainly across Central Lower. Most of the time we will see limited cloud cover with hot conditions. The first chance of rain across the northern section of the CWFA will come as early as the pre-dawn hours on Sun. A cold front extending from Ontario down through MN will try to push into Nrn Lower overnight. Showers and storms ahead of it will try to make it into the area, but will likely dissipate before making it. This is due to the fact that the low level jet and supporting wave will be well north of the area. Still can not rule out a few light showers/sprinkles making it in up north. Some small storm chances will linger through Sunday across the area. The front will be just north of the area, however we are expecting an MCS across WI could ride along this front, and potentially clip the nrn section of the area as it is dissipating. It will be riding into a fairly unstable area (CAPEs of 1000-2000 j/kg), but quite capped, and will likely ride the edge of the cap. Rain chances will drop a bit lower then for Sun night and Mon as the front is expected to push a bit further north. This will be the result of a wave that will riding NE into Canada and should stay NW of the area. The chances will then increase a little bit Mon night as the wave that rides NE Sun night and Mon will drag the front south a bit behind it. The front could make it down to around I-96. Max temps the next couple of days have the potential to warm a couple of degrees each day, with 90s likely by Monday as H850 temps approach 20C. This would be assuming little to no rainfall. .LONG TERM...(Tuesday through Saturday) Issued at 314 PM EDT Sat Jun 10 2017 Little question summer like weather will prevail most of this coming week before a return to cooler conditions comes in the following week. It will largely be dry Tuesday into Wednesday but later Wednesday into Thursday is when there is the best chance for most of the area to see a significant rainfall event. This happens due to widespread thunderstorm activity associated with the cold front. It should dry out Friday into Saturday but it will remain seasonably warm. More storms are possible later in the weekend. We still have our three storms over the north Pacific from Japan too the west coast of the United States. Plus our polar vortex like circulation over northern Hudson Bay. The hot weather we are expecting from Sun through Wednesday is from the lead storm coming on shore (happening as I write this) but it is trapped by an omega block due to next storm currently near the tip of the Aleutian Islands and a closed upper high between them. By early next week the second storm finally boots the first storm northeast into Southern Canada, shearing it out over the top of the upper ridge over the eastern United States. It is that lead system being sheared out that brings the thunderstorms later Wednesday into Thursday. Since there is two more systems behind that one, the second storm gets booted into western Canada by the third system (which by Friday is near the dateline). That system being booted into western Canada will keep the eastern upper ridge from totally breaking down and thus prevent it from cooling off much behind the front. It is not until early in the following week when the third system gets close enough the the United States to force the second system to dig southeast into the Great Lakes that the really cool air finally comes back to this area. More storms are possible next weekend as that second system starts to dig into the northern Plains and Great Lakes. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1130 PM EDT Sat Jun 10 2017 Vfr conditions will continue through Sunday evening. We will continue to carry LLWS in the terminal fcsts overnight due to wind speeds of around 45 kts at 2000 ft. Southwest winds will increase to 15 to 20 kts with gusts to 25 kts at all the terminals Saturday morning and afternoon before gradually subsiding Saturday evening. && .MARINE... Issued at 1005 PM EDT Sat Jun 10 2017 Extended the Beach Hazard Statement and Small Craft Advisory through Sunday as south flow looks to remain strong enough to continue to support hazardous conditions on the lake. The Gale Warning for the northernmost marine zone off Ludington remains in effect and will be replaced with a Small Craft Advisory once peak winds settle down below 35 knots. && .FIRE WEATHER... Issued at 314 PM EDT Sat Jun 10 2017 Fire danger remains elevated this afternoon due to the dry and windy conditions. Aside from a local area approaching Red Flag conditions, RH`s are remaining just a tad too high to justify a warning at this time. Winds will not be as bad, and RH`s will be similar on Sunday. && .HYDROLOGY... Issued at 151 PM EDT Sat Jun 10 2017 There are no changes from the last update. There are no concerns for flooding at this time. Chances for rain are low/zero through Tuesday. Rain chances may finally increase through the middle of next week. Convective precipitation may result in localized heavy rain at time, but prolonged heavy rainfall does not look likely. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through Sunday evening for MIZ037-043- 050-056-064. LM...Gale Warning until 5 AM EDT Sunday for LMZ849. Small Craft Advisory until 8 PM EDT Sunday for LMZ844>848. && $$ UPDATE...Meade SYNOPSIS...NJJ SHORT TERM...NJJ LONG TERM...WDM AVIATION...Laurens FIRE WEATHER...NJJ HYDROLOGY...JAM MARINE...Meade
Area Forecast Discussion
National Weather Service Jacksonville FL
850 PM EDT Sat Jun 10 2017 ...HEAVY AND LOCALLY FLOODING RAINFALL RETURNS... .UPDATE...Rainfall returned with a vengeance to inland locations this afternoon including Marion county where flash flooding due to rainfall accumulations of 3-5 inches within an hour in some areas caused major street flooding and a large sinkhole along State Road 200. A surface front lifted northward up the north- central Florida peninsula with a return of deep moisture with precipitable water rising to above 1.8 inches per the 00Z JAX RAOB. Low level ESE flow undercut upper level WSW flow within the southern stream jet. Upper level divergence, high moisture, slow storm motion, diurnal heating all contributed to locally heavy rainfall...with this pattern expected over the next several days. Recent HRRR guidance started to pick-up better initializing coastal showers within convergent bands setting up over our Atlantic waters while inland convection near and west of I-75 continued to fade and drift farther west. Updated the forecast to include coastal showers through the night with the low level trough axis meandering over the local area and upper level divergence and high moisture content continuing to stream overhead. Muggy overnight conditions under mostly cloudy skies are expected with low temps falling into the low/mid 70s. && .AVIATION...Coastal convection and low stratus will be possible early Sunday morning under onshore flow. Inland rainfall was dissipating at GNV this hour. SREF indicated potential for MVFR cigs moving inland from the Atlantic 09Z-12Z with a very low chance of IFR to potential LIFR near SGJ and GNV around sunrise (probabilities <15%). At this time will continue to trend toward MVFR cigs for coastal sites tonight. Will also continue with VCSH at coastal terminals tonight. Highest confidence for TS included at GNV Sunday after 17Z. Locally heavy rainfall and wet downbursts will continue to be largest concerns. && .MARINE...ESE winds 10 kts or less will prevail tonight with combined seas 3 ft or less. Updated forecast to include showers and isolated tstorms through the night. Rip Currents: Moderate risk this weekend due to onshore flow. && .PRELIMINARY POINT TEMPS/POPS... AMG 70 89 72 88 / 20 40 20 50 SSI 76 85 75 84 / 20 20 10 30 JAX 72 87 73 86 / 20 30 10 40 SGJ 74 86 74 84 / 30 30 10 30 GNV 72 88 72 86 / 50 70 20 60 OCF 72 89 72 87 / 30 70 30 70 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Enyedi/Shuler/Peterson
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
521 PM MDT Sat Jun 10 2017 .DISCUSSION...(This Evening Through Saturday) Issued at 205 PM MDT Sat Jun 10 2017 PAC NW Upper trough continues to support periodic impulses into the region, supporting a wavering frontal boundary over the FA. This will be the case through early next week, at which time the entire upper trough will finally eject over the region and support a vigorous storm system into the FA Monday. A shortwave trough is taking aim on the region and will provide enough forcing in the presence of the departing jet streak entrance region to support elevated convection tonight across the northern 2/3 to half of the fa. Staunch pos theta-e adv (indicated well at h7 with a bubble of +335K air advecting over the region ahead of the mid level trough) coupled with steep mid level lapse rates will support support 1000-2000 J/KG of elevated CAPE. Effective bulk shear numbers in excess of 50 knots coupled with CAPE/forcing parameters will be more than sufficient for a few rotating updrafts, supporting a severe threat, mainly large hail. HRRR UH tracks certainly support this as well. Best chance for storms will be from the central/northern Black Hills northeast out to Dupree. TS will exit the region early Sunday morning with ll flow becoming NE as the impulse forces pressure rises into the region. Generally quiet weather expected Sunday during the day as weak subsidence and ll dry NE flow supports subsidence over the region. However, the main upper low will begin to push toward the region Sunday night, supporting elevated pos theta-e adv over the region esp the western third. This will likely support diurnal convection over central/southern WY which will spread north overnight, esp over the far western third. Low level moisture adv will begin to slowly ramp up Monday as pos theta-e adv continues through Monday ahead of the advancing upper low. This may support a band of elevated convection through most of the FA moving north through morning and possibly into early afternoon. The main show will be Monday evening and overnight hours. Main upper trough will push into the region, supporting strong large scale ascent, with a potent 50-70 knot mid level jet streak. This will support impressive bulk shear values over 50 knots with steepening mid- level lapse rates. The main wild card will be the amount of moisture return back into the FA, which will be the determining factor on the intensity and coverage of expected severe weather. Forecast models have been running a little high on ll moisture advection with the last few systems, esp given the ongoing dry conds. However, given expected moisture pooling along the wavering front coupled with the weak southward surge of the ll frontal boundary Sunday and the proximity of the FA to deeper moisture (SE Nebraska), expect that moisture profiles should not be too far off in current GFS/NAM progs, which should support a good chance of supercell TS with potential upscale growth into a large severe MCS tracking NE across the central FA (just north of the sfc low), esp given LLJ development Monday night. Storms would likely fire in WY (possibly just south of our FA Monday evening) and shift NE and expand over the region Monday night. Large hail, damaging winds, and isolated tornadoes would be possible (given highly curved LL hodographs), with potential QLCS tendencies later Monday night. Cooler but mainly dry conds can be expected after Monday, with perhaps a few diurnal showers under the upper low Tues across NE WY. Upper flow will then trend WNW with subtle impulses in the flow perhaps supporting slight chances for SHRA/TS at times, but nothing to warrant a pop mention attm. && .AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening) Issued At 519 PM MDT Sat Jun 10 2017 TSRA will develop this evening across northeast WY/Black Hills region and then spread east/northeast overnight. MVFR CIGS/VSBYS will occur with the strongest storms along with hail/gusty winds. Outside of TSRA, VFR conditions will prevail through the period. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION...JC AVIATION...Helgeson