Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/12/20

Area Forecast Discussion
National Weather Service Des Moines IA
710 PM CDT Sat Apr 11 2020 ...Updated Aviation Discussion... .DISCUSSION.../Tonight through Saturday/ Issued at 306 PM CDT Sat Apr 11 2020 Initial push of warm advection and moisture into the state has produce scattered showers and a few storms across Iowa today. This initial surge continues eastward into this evening with precipitation spreading into eastern Iowa and northern Illinois. Additional scattered showers and thunderstorms seem likely across the south again later this evening into the overnight as another weak wave passes through near the Iowa/Missouri border. Meanwhile, a strengthening boundary will slowly into central Iowa overnight as low pressure deepens across the Plains. Wind fields are forecast to intensify through the night as the pressure gradient tightens with increasing cold advection into northwest Iowa. Forcing increases significantly into Sunday with the approach of the northern stream shortwave. Precipitation will increase in coverage and intensity into the morning across behind the boundary across the northwest third of Iowa. Models have trended slightly farther north with axis of main forcing and resultant QPF and this needs to be monitored in further runs. Impressive mid level QG and frontogenetical forcing will be ongoing for a good portion of the day across the north with banded snowfall likely. In addition, stability is quite weak with thunder possible in the far north enhancing snowfall rates. Rates of 1-2" seems quite possible near the Minnesota border for a few hours into Sunday afternoon. Amounts in the far northwest will likely be from 8-10" but could be even high should convective elements develop. The gradient of snow will be tight on the south side of the band where warmer air is expected to keep precipitation mainly liquid prior to the heavier QPF ending towards evening. Otherwise, winds strengthen during the day and into the evening with near blizzard conditions in the warning areas. A possible upgrade seems in the cards should the wind fields develop, although fracturing of stucco snow to reduce visibilities is somewhat difficult. Elsewhere, a wind advisory also seems likely to be issued in future forecasts as the top of the mixed layer is mostly 40-50kts in most locations later Sunday into Sunday night as strong cold advection spreads across the state. HRRR has been showing some decent instability in the far southeast by Sunday afternoon and there is some concern that the potential is being underplayed. Shear is not a problem with this system so everything depends on the ability for instability to develop given the extensive cloud cover and track of surface low. This will need to be closely watched with damaging winds and large hail possible, if greater instability would develop, a tornado would not be out of the question either. After the storm departs late Sunday night into early Monday, thermal trof will enter the state on Monday with a brisk and cold day. Some lingering clouds may persist in the north through the day given the cyclonic curvature and the approach of a weak shortwave late in the day. The overall upper pattern remains unchanged through the mid to late work week with a large upper trof continuing across the eastern half to two-thirds of the nation. This will keep open the reservoir of unseasonably cold air into the state during the work week with temperatures holding 15-20 degrees below normal for much of the time. Some slight moderation is expected by late in the period as the deep trof begins to migrate east with the amplitude of the upper flow flattening, allowing for some modification of the airmass in the Midwest. Chances for precipitation through the week will be limited with any rain/snow remaining light and rather limited in spacial extent. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 700 PM CDT Sat Apr 11 2020 VFR conditions this evening before the rain/snow develops by early Sunday morning. Ceilings will gradually lower late tonight and into the overnight hours and confident by 8-12z Sunday, at least IFR ceilings should be present. Lower confidence in the visibility restrictions and kept mainly MVFR until the strong winds develop late in the morning Sunday. Also, FOD, ALO and MCW will see snow toward the end of the TAF period and higher confidence in the lower visibility restrictions coupled with the potent northwest winds. && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 10 AM Sunday to 4 AM CDT Monday for IAZ016-017-023-024-033-034. Winter Storm Warning from 7 AM Sunday to 4 AM CDT Monday for IAZ004>007-015. && $$ DISCUSSION...Cogil AVIATION...Podrazik
National Weather Service Sioux Falls SD
1100 PM CDT Sat Apr 11 2020 .SHORT TERM...(This Evening through Sunday Night) Issued at 321 PM CDT Sat Apr 11 2020 At a synoptic level, WV satellite imagery and upper level analysis shows a pronounced closed low across southern AZ with a southern stream jet running across the southern CONUS and a strengthening northern stream jet from the eastern Dakotas eastward toward the Great Lakes. Closer to home in the form of more sensible weather, a couple of different areas of showers, one in NW IA and the other near and west of the James River. With temperatures in the 50s to even lower 60s, this has all been rain and should remain that way into the evening. By tonight, the more impactful weather begins as the right entrance region of the previously mentioned northern stream jet begins to induce and strengthen mid level frontogenesis. Guidance continues to suggest this frontal forcing is strongest in the 700:800 mb layer initially running near the MO River Valley across south central SD and eventually settling in from northeast NE, far southeast SD, and then toward south central MN, north central IA. Guidance also continues to depict some negative EPV* just atop this layer suggesting the potential for a contracting and enhancing of the strongest snow band (more on this later). All of this should establish a fairly coherent and robust band of precipitation through the second half of the overnight into much of the daytime hours Sunday. Better forcing should shift east of I-29 by early to mid evening with upper level subsidence shutting down the remainder of the precipitation across our area after midnight Sunday night. Precipitation Type: Forecast soundings suggest we should see a fairly clean transition from rain to a brief rain/snow mix to snow for most locations. The transition from rain to snow should be underway by late evening west of the James River working eastward with a changeover around or just prior to the daybreak hours along a Yankton to Sioux Falls to Worthington line. The remainder of NW IA may be closer to the mid morning hours, although likely much dependent on precipitation rates and potential for dynamical cooling. Areas near Ida Grove and Storm Lake will be the last to see the switch to snow with perhaps even a period of sleet or freezing as the colder surface air outruns a pocket of warmer air aloft. A few rumbles of thunder are also possible across this area. Amounts: Model progged PWAT are not anything abnormal in terms of climatology but the strong dynamics of this system should still produce some healthy QPF amounts. As previously mentioned, still plenty of suggestion in the models that we may see a tighter and heavier band of snowfall develop which may drive a narrow corridor of higher amounts. As is typical in these scenarios, agreement on where exactly this will end up is far from agreed upon although have noted a northward shift in guidance over the past 12 to 24 hours. The HRRR and RAP are generally furthest north with this area of higher QPF near and north of I-90 and NAM (and its derivatives), GFS and ECMWF south of I-90. SREF and WPC super- ensemble plumes further display this uncertainty with some locations exhibiting as much as a 0.75 to 1 inch spread in QPF. A couple of different options exist for a snowfall forecast...The first would be to continue to play the northward shift (HRRR/RAP) which after collaborating with WPC, wouldn`t be the first system recently to do this. The other thought is to follow the better mid level frontal forcing (NAM/GFS/EC) which is generally what this forecast package relied on. This also aligns relatively well with the HREF probability matched mean. This would put a band of 6 to 10+ inches from roughly Gregory to Beresford to Worthington with generally 2 to 6 inches buffering that. With all of that said, a quick cursory glance at the 18z guidance just coming in gives a little more credence to a northern solution. Impacts: Ground temperatures across the region are largely in the 40s with road temperatures likely higher than that. This may work to temper the travel impacts some, although with snow rates nearing or exceeding 1 inch per hour at times (supported by HREF probabilities and periods of deep dendritic layers exhibited in various soundings), these warmer ground temperatures should have no problem becoming overrun. This will result in slushy or snowcovered roads. Additionally, winds at the top of the mixed layer sit anywhere from 30 to 40+ kts which will help to produce winds gusts of at least 35 to 45 mph. This will result in some blowing snow and reduced visibility which given the expected wet nature of the snowfall, should be mainly confined to period of falling snow. Headlines: Have upgraded the remainder of the previous watch with an additional northward bump. This warning area may still need to be shift a row of counties or two (more likely north than south at this point) depending on where the final consensus for the heaviest corridor settles in. Have also covered the remainder of the coverage area with an advisory given the combination of snow and wind. .LONG TERM...(Monday through Saturday) Issued at 321 PM CDT Sat Apr 11 2020 With an active period in the shorter terms of the forecast, minimal changes were made in the extended portions of the forecast. Stubborn upper level troughing will no doubt keep our region below normal as far as temperatures with high temperatures thru Tuesday likely stuck in the 30s. May see some moderation later next week but still hedging toward below normal readings. A fairly disturbance ridden northwest flow aloft regime will keep us from staying completely dry during this time frame, although tough to pinpoint details on exact timing of any waves at this point. Significant precipitation doesn`t look overly likely beyond the weekend however. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1051 PM CDT Sat Apr 11 2020 Light rain is moving across the area, with the transition to snow already occurring for areas in central to east central SD, including KHON and K9V9. Snow transition for KFSD, KSUX, and surrounding areas expected before daybreak. Conditions will continue to deteriorate, with snow becoming heavier and northerly winds increasing through the morning, gusting up to 40 knots. IFR visibility and ceilings are expected, with LIFR conditions possible within the heaviest snow band and coupled with blowing snow. Conditions will begin to improve from west to east as the snow tapers off late Sunday afternoon through evening. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for SDZ066-067-069>071. Winter Storm Warning until 4 PM CDT Sunday for SDZ050-057- 063>065-068. Winter Weather Advisory from 4 AM to 7 PM CDT Sunday for SDZ040- 055-056-061-062. Winter Weather Advisory until 4 PM CDT Sunday for SDZ038-039- 052>054-058>060. MN...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for MNZ080-081-089-090-098. Winter Weather Advisory from 4 AM to 7 PM CDT Sunday for MNZ071- 072-097. IA...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for IAZ001>003-012>014-020-021. Winter Weather Advisory from 10 AM Sunday to 1 AM CDT Monday for IAZ022-031-032. NE...Winter Storm Warning from 4 AM Sunday to 1 AM CDT Monday for NEZ013. Winter Weather Advisory from 10 AM Sunday to 1 AM CDT Monday for NEZ014. && $$ SHORT TERM...Kalin LONG TERM...Kalin AVIATION...SG
Area Forecast Discussion
National Weather Service Grand Junction CO
548 PM MDT Sat Apr 11 2020 .SHORT TERM...(Tonight through Sunday night) Issued at 214 PM MDT Sat Apr 11 2020 The much-touted cold front remains to our north this afternoon. We`ve seen plenty of warm temperatures and some higher gusts this afternoon and this will continue as we head into the evening hours. Also, radar is just starting to show some development along the UT/CO border this afternoon which follows the HRRR forecast and is also where the best CAPE lies. Peak heating and a marginally unstable atmosphere ahead of the cold front should allow some showers to form and a few rumbles of thunder through this evening, mostly for our northern valleys. As far as the cold front is concerned, we`re still on track to see it move through overnight. It will be noticeable to most people as it moves through due to some gusty winds and accompanying precipitation. Guidance still showing the Flat Tops, Park and Elkheads seeing the best shot of some accumulating snow so the going advisories remain in effect. Any snow that does accumulate will quickly melt off Sunday morning once the sun rises. The northern San Juans and West Elks will also likely see some snowfall but amounts look to be in 3 to 6 inch range so held off issuing anything for now. Once the front moves through, we can expect variable cloudiness Sunday though some lingering showers will continue along the Continental Divide. Passage of the front will cause winds to shift to more northerly as cold advection kicks in bringing in cooler temperatures to the region. Normally, the coldest temperatures are found the second day after frontal passage and that will hold true with this front. Temperatures will be cooler Sunday but as the cold advection is just starting, the noticeably colder air won`t be here until Monday. .LONG TERM...(Monday through Saturday) Issued at 214 PM MDT Sat Apr 11 2020 While the calendar says it`s spring, many of us will wake up Monday morning and think it`s winter. When cold air moves in, MOS (or statistical guidance) is one of the first indicators that we`ll see cold temperatures moving in. Many times, as we get closer to the event, MOS guidance will start to warm up these cold temperatures. This time, they`ve stayed the same or gotten colder so confidence remains high that we`ll be seeing these cold temperatures Monday through Wednesday before things start warming up. As we`ve mentioned for many days now, the culprit was the cold front that moved through Saturday and Sunday. A trough then sets up and affects the entirety of the CONUS while remain remain on the western side of the trough axis. This will allow northwesterly to northerly mid to upper level winds to advect in much cooler air from the north. The growing season looks to have started for the Grand Valley, Moab, and also Montrose areas which is a concern. Hard freezes look probable for the Grand Valley and Montrose areas while Moab will be flirting with these values (<=28F) so issued a Freeze Watch for both Monday and Tuesday...and we might need one for Wednesday as well. As far as any precip is concerned, models indicate a few weak waves bringing light precip to the higher terrain mostly north of the I-70 corridor Monday evening and again Tuesday evening. Moisture is meager at best with forecast QPF amounts only reaching .01 inches through both days. Thus, expect isolated to scattered showers but little in the way of accumulation. The GFS likes the idea of orographically- enhanced snow for the Park and Elkheads early Wednesday morning while the EC keeps that area dry. The National Blend of Models likes the idea of this scenario and it seems reasonable so slight chance to chance showers for that area looks good. A stronger wave is then progged to move down from the north Wednesday evening into Thursday. It`s the evolution of this feature that is suspect as the EC brings an elongated trough through early Thursday morning and absorbs a shallow area of low pressure off the California coast whilst keeping precip over much of our CWA. The GFS favors a stronger low off the coast and the trough staying separate as it moves through. Either way, looks like some precip and unsettled weather early Thursday morning through Saturday and possibly beyond. Low to medium confidence at the moment as models do differ quite a bit. Temperatures will stay below average until Friday/Saturday when then finally get near climatological norms. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 548 PM MDT Sat Apr 11 2020 A storm system and its associated cold front will move through the region beginning this evening and will keep pushing south overnight. Showers are likely to impact KHDN, KRIL, KEGE, KASE before midnight with KMTJ, KGUC and KTEX joining the action later tonight. Precipitation is likely to begin as rain or a rain snow mix, turning over to all snow for all but KMTJ. Hedged toward MVFR visibility, though brief periods of IFR and possibly LIFR are possible with convective showers. Lightning is possible for KHDN and to a lesser extend at KEGE and KASE. Ceilings will be an issue for KRIL, KEGE and KASE from late evening into Sunday morning where cloud decks are likely to fall below ILS minimums. Gusty winds before and after the front with a wind shift are expected to impact all TAF sites as the system passes through the region. Finally, conditions improve during the afternoon, though mountain snow showers will continue over the mountains of the Continental Divide throughout the day. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Freeze Watch from late Sunday night through Monday morning for COZ006-011. Freeze Watch from late Monday night through Tuesday morning for COZ006-011. Winter Weather Advisory until 6 PM MDT Sunday for COZ004. Winter Weather Advisory from midnight tonight to 6 PM MDT Sunday for COZ010-013. UT...Freeze Watch from late Sunday night through Monday morning for UTZ027. Freeze Watch from late Monday night through Tuesday morning for UTZ027. && $$ SHORT TERM...TGR LONG TERM...TGR AVIATION...NL
Area Forecast Discussion
National Weather Service North Platte NE
648 PM CDT Sat Apr 11 2020 .SHORT TERM...(This evening through Sunday night) Issued at 353 PM CDT Sat Apr 11 2020 The primary forecast challenges the next few days revolves around the incoming winter storm followed by unseasonably cool conditions. So far today, a surface cold front bisects the forecast area, generally laying along Hwy 2 as of 20z. Mid level frontogenesis has been increasing across northern Nebraska per RAP mesoanalysis and scattered rain showers. Isentropic analysis also indicates broad lift, while decent low level moisture advection is occurring over southwest Nebraska as dew points approach 40F. This evening and tonight... Ingredients continue to come together for a potent winter storm to affect western and north central Nebraska. The primary surface low deepens as it spins up over the CO/KS plains. Meanwhile, the heart of the upper trough traverses the Dakotas, but strong forcing stretches into northern Nebraska. In between, strong CAA takes over at H85 with temps dropping to around - 9C. The combination results in scattered activity becoming more widespread across northwest Neb, then overspreading the rest of the Sandhills overnight. Precip will remain as rain through about 03z, then a transition to snow begins in northern Sheridan and Cherry Counties. The switchover slides southeast overnight to where the whole forecast area should be snow by 12z. The latest guidance, including CAMs, suggests more scattered nature of the precip across SW Neb due to some dry air intrusions below H7 and weaker forcing at H7-5. However, a mesoscale band is possible toward dawn, which may be responsible for most of the snow accumulation there. The Sandhills, and particularly areas near the SoDak border, feature the best combination of moisture and forcing. Snow totals have lowered slightly southwest (generally 1-2") and along Hwy 2 (mainly 2-4"), while totals have changed little across the northern Sandhills (5- 7"). With that said, kept all headlines the same. Much of the accumulation will occur within about a six hour window, where snow rates will approach 1"/hr at times. Across the north, X-sections indicate some theta-E folding, and forecast soundings indicate more of the thermal profile landing in the DGZ. Along with the snow, wind is a major factor with this system. The sfc low makes a large pressure gradient, while the shortwave and nearly unidirectional flow below H7 help mix greater speeds down. Northerly winds steadily increase through the night with gusts topping 40mph by 12z. Significant blowing and drifting is expected, but the the wet nature of the snow and low SLR`s to start should keep conditions below blizzard criteria. Sunday... Snow continues across the forecast area during the morning, then tapers fairly quickly from west to east in the afternoon. Winds strengthen further through about 18z, then slowly wane into the evening. Peak gusts range from around 40 mph north to 50+ mph in the south, aided by nearly 2mb/hr surface pressure rises. Even as the falling snow comes to an end, blowing snow will remain a concern. Will need to watch for a second round of light snow/flurries in the panhandle late afternoon to early evening as upslope flow resumes. Pushed max temps down a degree or so from previous forecast using the cooler guidance. Highs range from upper 20s along the Pine Ridge to lower/mid 30s far southwest. Lows Sunday night may not be cool enough due to fresh snow pack and clearing skies. If winds trend lighter, this will be a setup for potentially record lows. NAEFS ensembles suggest record cold H7 temps in northern Neb and H85 temps cooler than 1% of climo. .LONG TERM...(Monday through Saturday) Issued at 353 PM CDT Sat Apr 11 2020 Monday and beyond... The large upper trough centered over the Great Lakes slowly retreats eastward, but Nebraska remains in northwest flow for the foreseeable future. A couple (very) weak boundaries brush the area during the week, which will keep moisture chances low. The best shot comes Thursday into Friday as a somewhat stronger shortwave rounds the trough while upslope flow takes over closer to the surface. Temperatures remain cool, including highs in the 30s/40s Mon and Tue and near record lows Monday night. Cross our fingers for 60F by next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 611 PM CDT Sat Apr 11 2020 Multiple aviation concerns within the TAF period as a winter storm impacts the region tonight-Sunday. Latest radar display shows scattered rain showers across far northern NEB and isolated showers across southwest NEB. Latest obs show VFR conditions across much of the Sandhills and southwest NEB, except IFR ceilings across extreme northwestern NEB. Current thinking is greatest areal coverage of showers will be confined to northern NEB late today/evening with just passing isolated showers to the south. This evening will see a changeover to snow across northwestern NEB with precipitation spreading gradually across the area overnight, becoming snow as well. Meanwhile, ceilings will deteriorate area-wide overnight down to IFR to low-end MVFR (less than 2 kft) that will then prevail into early tomorrow before improvement to low-end VFR (less than 7 kft) or high-end MVFR. Meanwhile, visibility as low as 1/2 mile or less is possible at times with moderate to heavy snow along with blowing snow. That said, greatest snowfall is expected across northern NEB and parts of the Sandhills, elsewhere generally an inch or less is forecast across much of southwest NEB. Strong winds will develop tomorrow with gusts as high as 40-50 mph as the low pressure system evolves from the Central High Plains this evening towards eastern OK/MO tomorrow. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 1 AM CDT /midnight MDT/ to 10 PM CDT /9 PM MDT/ Sunday for NEZ022-035>038-056>059. Winter Storm Warning from 1 AM to 10 PM CDT Sunday for NEZ006>010-025>029. Winter Storm Warning until 7 PM CDT /6 PM MDT/ Sunday for NEZ004- 005-023-024-094. && $$ SHORT TERM...Snively LONG TERM...Snively AVIATION...ET
Area Forecast Discussion
National Weather Service Miami FL
736 PM EDT Sat Apr 11 2020 .Aviation... Showers and thunderstorms will continue to affect the east coast terminals through the early evening hours. There could be periods of MVFR to IFR across the terminals of Miami Dade County as these thunderstorms move through this evening. Afterwards, VFR conditions should prevail through the overnight hours and into Sunday morning. Winds will increase out of the Southeast and they will be gusty at times on Sunday. && .Update... Updated the forecast based on radar trends. Showers and thunderstorms will continue this evening especially across Miami Dade County as they move southeastward. These storms could contain gusty winds, heavy rain,small hail, and funnel clouds as they move through. As the evening progresses, these thunderstorms will begin to diminish and many areas will dry out during the overnight hours. Low temperatures tonight will remain on the mild side as they will drop into the upper 60s across the northwestern interior to the mid 70s across the east coast metro areas. On Sunday, the winds will increase out of the southeast as the pressure gradient across the region increases. Winds will be gusty at times during the day on Sunday. A few showers are possible during the afternoon hours especially across the Lake Okeechobee region. High temperatures on Sunday will range from the mid 80s across the east coast to the mid 90s across the interior sections. && .Prev Discussion... /issued 217 PM EDT Sat Apr 11 2020/ Short Term... Today... A differential heating boundary has develop across central Miami-Dade County where some clearing of stratiform clouds has allowed increased heating across Southern portions of the peninsula. On vis satellite you can also, a well-develop cu field beginning to form. Winds have become a little backed and easterly at the surface, with upper level HRRR model winds veering westerly with height. With the increased heating MLCAPE values have soared to be above 3000 J/kg over southeastern Florida with 50 to 60 knots of effective bulk shear. 0-3 SRH values over the southeastern metro are 150-200 m2/s2 and significant tornado parameter (STP) indices around 1 over metro Miami-Dade. The storm relative mean wind is oblique to the current boundary axis across Miami-Dade county support semi-discrete supercell storm mode. There is increasing potential for severe supercells across southeastern Florida this afternoon, with main hazards being damaging winds, large hail and even the possibility of a tornadoes. If multiple round of storms develop over the same area heavy rainfall may lead to localized flooding of low-lying poor drainage. Due to the weak ascent there is still some uncertainty that this event will materialize. Sunday and Monday... High pressure will dominate for the beginning of the week. Even so, a few showers may be possible in the Lake region. With the high to the east, a south to southeast flow will bring a warming trend to the area, helping to boost temps into the upper 80s to low 90s. Long Term (Tuesday through Friday)... A cold front will stall around north central Florida on Tuesday, permitting southern Florida to remain in the warm, moist airmass around the Atlantic surface high pressure. As the week progresses, a reinforcing front pushes across the southeastern United States which will allow the boundary to advance southward into southern and central Florida. The main stories through the rest of the week will be warm temperatures and increasing rain chances. There is still some uncertainty with the timing and location of the front before it stalls. If the location is further south than currently forecast, rain chances will increase while the increased cloud cover may help cool temperatures a bit. Either way, the chances of rain will include the potential for heavy rain as well, especially with more robust convection like thunderstorms. Marine... Showers and thunderstorms may bring locally hazardous weather to the Atlantic waters, including Biscayne Bay through this evening. This includes gusty wind and waterspouts as possible hazards. Then, conditions improve for the next couple of days as high pressure builds in. Even so,wind may continue to be a concern for small craft, as a south to southeast wind of 15 to 20kts is forecast through at least the first half of the week. Small Craft Should Exercise Caution, mainly in the Atlantic waters of South Florida. Aviation... Unsettled weather is forecast across South Florida through the evening hours. Strong gusty showers and possibly some isolated strong to severe thunderstorms are possible, mainly south of Alligator Alley. The hazards include hail, downbursts, and funnel clouds are possible. Also, an isolated tornado can not be ruled out. Active weather is possible well into the overnight hours. Tomorrow should see quieter weather, but the wind is forecast to be breezy out of the southeast. Beach Forecast... A southeast wind is forecast to strengthen for the next few days. this would keep an enhanced risk of rip currents for the Atlantic beaches for at least the first half of the week. && .Preliminary Point Temps/PoPs... West Palm Beach 74 85 76 89 / 30 20 0 10 Fort Lauderdale 75 85 78 87 / 30 20 0 0 Miami 75 85 77 88 / 30 10 0 0 Naples 72 90 75 88 / 0 0 0 0 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && Update...55/CWC Aviation...55/CWC
Area Forecast Discussion
National Weather Service Marquette MI
1106 PM EDT Sat Apr 11 2020 .UPDATE... Issued at 1105 PM EDT SAT APR 11 2020 Quick check of incoming 00z NAM/WRF-ARW/WRF-NMM runs strongly support the overall look of going fcst for w and central Upper MI with regard to the upcoming late season winter storm. All focus heaviest pcpn amounts across the high terrain of Baraga/Marquette counties where qpf of 1.75 to 2.25 inches is indicated by 12z Mon. The axis of heaviest qpf then extends sw, centered generally across Iron County. Snowfall will be very heavy across the warning area Sun night and suspect that travel may become impossible for some areas by Mon morning. New 00z CMC has not yet started arriving, but it was noted that the 18z run took a decent shift eastward with its heaviest qpf axis. Will be interesting to see if the non-NCEP 00z models support the above scenario. && .SHORT TERM...(This evening through Sunday) Issued at 438 PM EDT SAT APR 11 2020 WV imagery and RAP analysis indicated mainly zonal flow across the northen CONUS with a shortwave trough sliding to the north through northern Ontario. A vigorous upstream shortwave was moving through northeast WA while a southern stream shrtwv was moving through sw AZ. At the surface, the northern Ontario shrtwv and associated 1002 mb sfc low was dragging a cold front through western Lake Superior. Mid/high clouds with the shrtwv tail and developing WAA pattern were streaming through mainly western Upper Michigan. Otherwise, plentiful sunshine has helped push temps into the mid 50s to aroudn 60, except along Lake Michigan where readings remained in the 50s. Tonight, cooler air will move into the area with winds veering northerly behind the cold front. However, with radiational cooling limited by a continued increase in mid/high clouds, temps will only drop to around 30. Sunday, the deepening mid level trough over the Northern Plains and a developing sfc trough from Oklahoma to northern Lower Michigan will support strengthening deep isentropic lift over the region with strong moisture transport toward Upper Michigan. The onset of the heavier pcpn during the afternoon reflects a compromise between the faster NAM and the slower GFS/ECMWF and high res models. After an initial warmup into the mid to upper 30s, increasing pcpn with evaporative cooling will change most of the pcpn quickly from any rain or mix to snow. The exception will be close to Lake Michigan Where the warm low layer may persist. Snow accumuations of a couple inches will already be possible by early evening, with higher amounts possible if models trend toward the NAM. .LONG TERM...(Sunday night through Saturday) Issued at 406 PM EDT SAT APR 11 2020 The main focus in the long-term remains the major winter storm for Sunday night into Tuesday. As this dynamic system lifts across the region, deepening as it traverse lower Michigan and Lake Huron, it will bring a plethora of impacts to the Upper Peninsula. Travel conditions will deteriorate rapidly Sunday night into Monday morning, and linger throughout much of Monday into the overnight hours. It is not out of the question that for a period of time on Monday that some location could see blizzard conditions as north to northwest winds ramp up. Snow is expected to be wet and dense, thus snow removal will be very difficult and the combination of dense snow and stronger winds on Monday will cause concerns for some tree damage and power outages in spots. These winds will also allow large waves to build along the Lake Superior shoreline over the tip of the Keweenaw, and then near/east of Big Bay to Crisp Point. Significant beach erosion may occur in spots and lakeshore flooding will be possible! The highly advertise system progged to bring widespread snow for Sunday night into Monday is still on track. The majority of the widespread heavy, dense snow does look to fall Sunday night into Monday morning as the main 850mb low lifts across central Upper Michigan, pumping in plenty of warm air advection. Additional large- scale lift arrives from an intensifying vort max approaching, coupled jet structure aloft, and deep area of frontogenesis lingering overhead. Given the impressive synoptic scale lift, this helps boost confidence in the higher QPF and snowfall totals. With the surface low tracking over lower Michigan and Lake Huron, and the 850mb low up across far eastern Upper Michigan, northeast to north upslope flow will aid in augmenting snowfall totals locally over the higher terrain out west and in the north-central Sunday night/Monday morning. It is not out of the question that we could get some lake- enhancement as well off of Lake Superior, more so out west where temperatures aloft will be a bit colder. Mid-day Monday into Tuesday morning, the system quickly lifts northeast of the region. Expect lake-enhanced snow to persist during Monday afternoon, mainly across the west and northern parts of Upper Michigan as wrap around snow continues to linger. Winds will also ramp up quickly on Monday, as conditions as cold air advection favors deeper mixing and the ability to tap into 30-40 knot winds aloft. Widespread winds of 35 to 45 mph look likely, with the strongest winds expected near the Lake Superior shoreline. Monday night into Tuesday, the colder air maintains it`s grip on the region so we should see lake-effect snow showers persist across the WNW wind snow belts. Did upgrade watches to warnings with the afternoon update as it looks like at least 1 foot of snow will be possible for locations out west and in the north-central. Areas across the higher terrain could pick up more snow due to terrain enhancements. Menominee, Delta, and northern schoolcraft counties look to be on the edge of the rain/snow line and could go either way on p-type Sunday evening as warmer air arrives, but they should switch back over to snow Sunday night. Don`t have nearly as much ice as what was previously in the forecast as the rain/snow transition zone where a wintry mix of sleet, freezing rain, and snow looks to be fairly narrow. With the potential for this wintry mix before switching over to accumulating snow by Monday morning, did opt to issue an advisory for those locations. Did not spend much time looking further out into the week, but persistent cold air advection continues to stream overhead. Therefore, we should see the below-normal temperatures persist at least through mid-week before we start to see temperatures modify. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 731 PM EDT SAT APR 11 2020 VFR conditions will prevail at KIWD/KCMX/KSAW into Sun morning. Heading thru Sun aftn, snow will spread northward into the nw half of Upper MI. As a result, expect conditions to fall to MVFR at KIWD/KCMX in the late aftn to early evening hrs. Heavier snow is more likely to impact KSAW, resulting in conditions falling to LIFR by evening. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 438 PM EDT SAT APR 11 2020 Although a sfc trough will pass across Lake Superior tonight, winds should remain mostly blo 20kt. Low pres will then organize over the Southern Plains on Sun. This low will rapidly deepen as it crosses the Great Lakes region Sun night/Mon morning. By Mon evening, deep low pres will be located s of James Bay. This strong system will likely bring gales to all off Lake Superior late Sun night through Mon evening with storm force gusts also likely developing over the east half Monday by late morning into Monday evening. A ridge of high pressure will slowly build in behind this exiting low pressure system on Tuesday as winds gradually diminish below 20 knots by Tuesday evening. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning from 5 PM EDT /4 PM CDT/ Sunday to 2 AM EDT /1 AM CDT/ Tuesday for MIZ001>003-009-084. Winter Weather Advisory from 5 PM Sunday to 8 AM EDT Tuesday for MIZ085. Winter Storm Warning from 5 PM Sunday to 8 AM EDT Tuesday for MIZ004>006. Winter Storm Warning from 2 PM Sunday to 4 PM CDT Monday for MIZ010-011. Winter Weather Advisory from 3 PM EDT /2 PM CDT/ Sunday to 5 PM EDT /4 PM CDT/ Monday for MIZ012-013. Lake Superior... Storm Watch from Monday morning through Monday evening for LSZ249>251-266-267. Gale Watch from late Sunday night through Monday evening for LSZ162-240>248-263>265. Lake Michigan... Gale Watch from Monday morning through Monday evening for LMZ221- 248-250. && $$ UPDATE...Rolfson SHORT TERM...JLB LONG TERM...Ritzman AVIATION...Rolfson MARINE...JLB
Area Forecast Discussion...UPDATED
National Weather Service Springfield MO
911 PM CDT Sat Apr 11 2020 ...MESOSCALE DISCUSSION... Issued at 841 PM CDT Sat Apr 11 2020 Minor update this evening to add a marginal/limited threat for some isolated hail up to the size of quarters, mainly across southeast Kansas and western Missouri. 00z KSGF sounding measured around 1000j/kg of most unstable CAPE (mainly elevated/above 700mb), 8.0C/km mid level lapse rates and 45kts of effective bulk shear. A 45-50kt 850mb llj was in the process of developing across eastern Oklahoma and was transporting abundant moisture into the area. Regional radar and satellite imagery continues to show a developing area of showers and storms across Oklahoma and western Arkansas. This area will continue to move northeast and into the area overnight, especially after 06z and generally along and south of I-44. Areas west of Springfield will have the highest instability overnight therefore can`t rule out an isolated severe storm with hail to the size of quarters in that area given the sampled airmass this evening. Overall though the severe risk is marginal overnight given the limited spatial threat area. Southerly wind gusts will continue to be around 30 mph at times tonight as the surface low continues to strengthen across western Kansas. This will also keep temps from falling too much overnight with most places remaining around 60. 00Z is just now coming in and will have to analyze how much instability can be realized tomorrow afternoon ahead of the incoming front. At this time, it looks like off and on morning showers/storms may exit briefly by mid day or early afternoon. If this occurs, then destabilization would allow for the development of strong to severe storms by late afternoon and evening. 00z HRRR and 00Z NamNest continue to indicate a broken line of strong to severe storms tomorrow afternoon/evening with the strongest storms closer to the Missouri/Arkansas state line. Confidence however is still low on the strength of storms and potential impacts tomorrow. Will continue to analyze the details tonight. Lastly, surface winds Sunday night look strong as the surface low exits the region and continues to deepen. Surface winds of 40-45mph look likely and a Wind Advisory will likely be needed for portions of the area Sunday night. && .SHORT TERM...(This evening through Monday morning) A cluster of showers and thunderstorms impacted nearly all areas of extreme southeast Kansas and the Missouri Ozarks today. This convection has exited east and has allowed for a few hours of dry and mild weather. As a matter of fact, temperatures were warming quickly back into the 60s as skies cleared and wind gusts picked up across the Osage Plains and western Ozarks. For tonight, continued mild temperatures are expected, and most areas should remain dry through the mid evening hours. Convection then will spread into southern Missouri by late evening and continue through the overnight period across south central Missouri. We can not rule out some convection northwest of Interstate 44 either, although chances are better to the south tonight. At this time we are not expected severe weather tonight. By tomorrow however, we could experience some organized thunderstorms as an upper level storm system approaches from the west. Some of the HIRES models are indicating a high frequency of thunderstorms within a decently sheared airmass. Instability levels are uncertain for tomorrow, and could limit the strength of thunderstorms. At this time we feel as though the most intense storms will have the potential for producing large hail up to quarters and damaging wind gusts. We could also experience some localized flooding. Average storm total precipitation will be around one inch, with pockets of heavier amounts. Colder air will spread into the region as thunderstorms are exiting Sunday night into Monday morning. Overnight lows will fall below freezing in many areas. .LONG TERM...(Monday night through Saturday) We will need to monitor for the risk of freezing conditions again Tuesday and Wednesday mornings as readings fall into the upper 20s and low 30s. Mainly dry conditions are expected Tuesday and Wednesday with highs ranging from the upper 40s to the middle 50s. By Thursday, models have been consistently showing the return of a warm front becoming stationary either directly over or somewhere near the Ozarks. Upper level flow will be zonal to slightly from the northwest, which could trigger multiple rounds of showers and thunderstorms from Thursday into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 614 PM CDT Sat Apr 11 2020 Ceilings will likely remain VFR early in the period however conditions are likely to drop into MVFR conditions after 06z as rain moves into the area. Could be an isolated thunderstorm however left as VCTS for now. Southerly winds around 20kts with gusts around 30kts will continue through 06z as well. After 06z, low level wind shear will develop at the sites. Scattered showers and an isolated thunderstorm will be possible with best chances closer to BBG. There will likely be a brief break in the rain before another batch moves in Sunday afternoon and evening. Thunderstorms are likely to occur Sunday evening. Winds will then begin to switch to the west and then northwest at the end of the period. Just beyond this forecast period (00Z), winds will increase out of the northwest with gusts around 40kts possible. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ MESOSCALE...Burchfield SHORT TERM...Cramer LONG TERM...Cramer AVIATION...Burchfield
Area Forecast Discussion
National Weather Service San Diego CA
121 PM PDT Sat Apr 11 2020 .SYNOPSIS... Dry and warmer weather today most areas, with isolated showers still possible on the coastal mountain slopes and foothills. Another weak trough will develop Sunday through Monday, lifting the moist air in place along and west of our mountains, to generate some occasional, light precipitation. The trough will move east Tuesday, setting us up for some dry and warmer weather through Thursday. A more unsettled pattern returns late next week for cooler conditions, more clouds, and even the potential for more showers. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Skies were clear over a large part of SoCal this afternoon, except for central San Diego County, where low clouds were widespread. the added sunshine and lack of precipitation has boosted midday temps in many areas from 6-10F over yesterdays readings. Surface pressure gradients were beginning to increase onshore, but wind reports were still mostly light. Clouds were thickening on the west slopes of the San Diego Mts midday so it looks like more showers are possible there this afternoon. Credit the recent HRRR model runs for capturing this development. Even our local 06Z WRF model had a couple of spots there this afternoon. Other than a few light showers over the mts/deserts today, it was dry for the first time in a while. No guarantees this will last though as the atmospheric pattern over the Hemisphere becomes highly amplified with a large trough over the continental U.S, and a ridge over the EastPac. The trough will be large enough to drop sfc pressure over the West, and create cyclonic flow aloft over CA. This looks sufficient enough for widespread saturation over SoCal, which in turn results in an abundance of clouds, and pockets of light precip breaking out at times. Most, if not all of this will be along and west of the mts, with the best chance on the coastal mtn slopes and foothills where the moist air is forced upward due to the onshore flow. Weak upper-level disturbances in the flow may enhance the lift at times. POPs are low because this precip is likely to be intermittent, scattered and light if and when it materializes. It isn`t until sometime Tuesday that we exit this pattern, heights rise, flow aloft becomes neutral to anticyclonic and atmospheric moisture drops. The ridge off the coast never arrives, but has some influence over SoCal, enough for a mostly clear and warmer interlude during the midweek period. This will give a chance to get your gardens planted ahead of another possible free watering. Toward the end of next week, the pattern once again turns cyclonic aloft as more troughing envelops the West. The medium range 12Z model guidance suggests another rogue low pressure center will drop south along the Coast, and turn inland somewhere over the all-too-familiar pattern this year. There is no consensus with timing or track of this feature yet. As a matter of fact, uncertainty is higher than average, due to the spread and clustering of the model`s ensemble members, but given the repetitive nature of this pattern over the past Winter, it is hard to ignore. At the very least, look for cooler and unsettled weather by next weekend, with a chance of showers at some point. && .AVIATION... 111930Z...Coast/Valleys/Mountains...Areas of SCT to locally BKN clouds with bases 2000-3000 feet MSL will continue through this afternoon. Widespread low clouds will move in this evening after 02Z with bases around 1500-2500 feet, spreading 20+ miles inland overnight, with higher terrain obscurations possible. Some afternoon scatter out is possible Sunday, but most locations over and west of the mountains will have persistent low clouds throughout the day. Light showers may occur at times west of the mountains Sunday. Deserts... FEW-SCT clouds at/above 7000 feet MSL will continue to diminish this afternoon. Mostly clear with unrestricted vis this afternoon through Sunday. && .MARINE... No hazardous marine weather is expected through Wednesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...10 AVIATION/MARINE...Connolly
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday) Issued at 354 PM CDT Sat Apr 11 2020 Active weather dominates our short-term period as a strong system impacts the region. The focus for this evening will be on timing and placement of thunderstorm development and severity potential. Attention then turns to hazards associated with an advancing cold front set to move through the CWA tomorrow. 20Z water vapor shows a cut-off upper low spinning over the AZ/ Mexico border, and an upper trough digging into the northwestern CONUS. At the surface, the ridge that was positioned over eastern KS/western MO yesterday is now located over the Carolina coasts. A deepening surface low was sitting over central KS at mid afternoon. With the aid of southerly flow, dewpoints have steadily increased today and are now in the low to mid 50s in eastern KS and a dryline is evident on surface maps extending from the low, southward into OK and TX. The warm and moistening atmosphere has led to further destabilization of our airmass with afternoon CAPE values ranging from 1000 J/kg near the NE state border to 2500 J/kg in south-central portions of KS. A low level jet is progged to strengthen near and just south of I-70 after 00Z, which is also when the HRRR and RAP, in agreement with some other convective allowing models (CAMS), show thunderstorm initiation over central and northeastern KS. Effective bulk shear values are forecast to range from about 30 to 40 kts. The combination of shear and CAPE could allow for some healthy updrafts leading to strong to severe thunderstorms. The main concerns will be large hail and damaging downburst wind. Storms should weaken after midnight but scattered showers may linger into Sunday morning. Attention then turns to the progression of a sharp cold front as it marches across the area tomorrow. North-northwest winds quickly increase behind the front and will become sustained between 25 and 35 mph with gusts to near 55 mph possible at times during the afternoon. Thus, a High Wind Warning has been issued for the western CWA with a Wind Advisory for the eastern half. Depending on the timing of the front, another round of strong to severe storms will be possible tomorrow afternoon just ahead of the boundary in eastern KS. Stratiform light rain is expected behind the boundary and efficient CAA will cause temperatures to plummet throughout the day. A wintry mix of precipitation is even possible in northern and north-central KS late in the day. .LONG TERM...(Sunday night through Saturday) Issued at 354 PM CDT Sat Apr 11 2020 Unseasonably cool temperatures will then settle in for the week in the wake of this weekend`s system. Temps early Monday will likely be in the upper 20s with afternoon temps only warming into the 40s (feeling more like late February). Tuesday morning also looks to be below freezing area-wide with locations in northern KS experiencing sub-freezing conditions again Wednesday and Thursday morning. While temperatures moderate a bit through the week, we will remain below average with large scale troughing in place over a wide swath of the country. A return to more seasonable conditions can be expected next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 638 PM CDT Sat Apr 11 2020 Main concern will be convection through 06Z, primarily at TOP and FOE. Short term models suggest development at TOP and FOE in the 01Z to 04Z time period. Isolated tsra may affect MHK after 01Z. Forecast soundings suggest mvfr cigs developing after 06Z and lowering to IFR after 10Z. A strong cold front will move through the terminals in the 16Z to 19Z time period. Winds will shift to the northwest and increase to around 22 kts with gusts up to 48 kts at MHK and around 37 kts at TOP and FOE. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 10 AM to 10 PM CDT Sunday for KSZ011-012-023-024-026-038>040-054>056-058-059. High Wind Warning from 10 AM to 10 PM CDT Sunday for KSZ008>010-020>022-034>037. && $$ SHORT TERM...Teefey LONG TERM...Teefey AVIATION...53
Area Forecast Discussion
National Weather Service Tulsa OK
923 PM CDT Sat Apr 11 2020 ...UPDATE... .DISCUSSION... Area radars detecting scattered sub-severe convection across parts of eastern OK into western AR, with additional storms across southwest into central OK. This activity has moved off the dryline, with the supercell near Lawton currently tracking due east. Surface instability is essentially nil across the forecast area, although an increasing low-level jet will allow storms to fester through much of the night. Forecast soundings show around 1000-1200 J/Kg of elevated instability and 0-6km bulk shear should be around 40-50kts, so a few severe storms will be possible. Large hail will be the main threat. Will lean toward the HRRR for the remainder of the night, and have lowered PoPs across much of the area after 09Z. && .PRELIMINARY POINT TEMPS/POPS... TUL 60 74 32 50 / 60 80 10 0 FSM 58 72 37 54 / 80 90 50 0 MLC 60 73 35 52 / 80 90 10 0 BVO 58 73 31 50 / 30 70 10 0 FYV 56 69 32 50 / 60 90 60 0 BYV 55 70 32 49 / 70 80 70 0 MKO 59 72 34 50 / 60 90 20 0 MIO 58 71 31 48 / 50 90 40 0 F10 60 73 34 50 / 70 80 10 0 HHW 61 73 38 55 / 50 90 10 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18