Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/08/20

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
926 PM CDT Tue Apr 7 2020 .UPDATE... Issued at 925 PM CDT Tue Apr 7 2020 Forecast is doing okay so no major changes for now. Did lower pops some late tnt since latest CAMS are much less aggressive with late night pcpn. Temperatures look okay. && .SHORT TERM...(This Evening through Wednesday Night) Issued at 321 PM CDT Tue Apr 7 2020 The forecast challenge is where/when tonight`s cold fropa wrings out some shower potential, along with if there ends up being some potential for "instability showers" sneaking down out of North Dakota into northeast South Dakota/west central Minnesota Wednesday afternoon/early evening. Also will need to re-investigate strength of winds on Wednesday. Currently, skies are sunny across the region, and temperatures are warming into the 60s and 70s across the vast majority of the CWA. Winds have come around to a westerly direction and becoming breezy out across the Missouri River valley, while light and variable winds continue to be noted further east. The cold front of interest for later tonight is analyzed back over northern Montana at this time. So, later tonight, said cold front will sweep southeastward through the region. This will set the stage for, perhaps, some late night/early Wednesday morning iso`d/sct`d rain showers over the CWA, mainly south of U.S. Highway 212. Just a few hundredths of precipitation potential, but behind the fropa, winds will switch around to the northwest and begin a pattern of low level caa that will likely not end before the end of the Wednesday night forecast period. After sunrise, daytime mixing, in tandem with a decent surface pressure gradient across the state, will work to create some rather strong winds on Wednesday. Generally speaking, sustained winds of 25 to 35 mph are probable, particularly the 25 to 30 mph range, so marginal advisory strength in that respect. But, the gust potential on Wednesday, if the NAM12 in BUFKIT is right, and the RAP13 in BUFKIT is half right, would easily set up in the 45 to 55 mph (decent advisory strength gusts). A few locations throughout the Missouri River valley could see gusts at or above 58 MPH (significant non-thunderstorm wind gusts!). Also, given the set up on Wednesday, won`t be taken by surprise to see some "heat of the day"/steep-low-level-lapse rate-aided popcorn showers developing on radar by mid to late afternoon across North Dakota and rotating down across northeast South Dakota and west central Minnesota. And, the NAM and RAP agree that much of any developing/growing CU will be living in the -10C to -30C temperature range, so some lightning and thunder might not be out of the question (or graupel) either. Overall, looking at the vast majority of the CWA remaining at or above the freezing mark overnight (lows progged into the 30s and low 40s). Much cooler conditions are in order, though, for Wednesday and Wednesday night, with highs on Wednesday likely only topping out in the low 40s to low 50s, and low temperatures Wednesday night probably dropping into the 20s to around 30 degrees. .LONG TERM...(Thursday through Tuesday) Issued at 321 PM CDT Tue Apr 7 2020 Overall, the extended period is shaping up to be cool (at times cold) with below normal temperatures. Surface high pressure will be building south into the region on Thursday, with breezy/windy conditions within the tighter pressure gradient pattern over the northern plains. Surface high moves overhead Thursday night, setting the stage for ideal radiational cooling and chilly temperatures. Brief warm up returns for Friday, and to a lesser extent on Saturday as we get back into return flow warm air advection. By Sunday and into early next week it appears a stronger surge of cold air moves southward across the northern plains, with high temperatures well below normal. Highs Sunday and Monday may struggle to reach 40 degrees for most areas. The best chance for any widespread measurable precipitation appears to be late Saturday into Saturday night, and continuing into Sunday. This looks to be mainly across western and central SD as an area of low pressure over the northern Rockies slides southeast into the central plains. Would not be surprised to see accumulating snow in these areas given the thermal profiles and surface temperatures heading into Saturday night. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 618 PM CDT Tue Apr 7 2020 VFR skies/vsbys are expected through tonight across the entire region. Winds will also turn gusty, especially Wednesday afternoon. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TDK SHORT TERM...Dorn LONG TERM...TMT AVIATION...TDK
Area Forecast Discussion
National Weather Service Birmingham AL
715 PM CDT Tue Apr 7 2020 .UPDATE... For 00Z Aviation. && .SHORT TERM... /Updated at 1130 AM CDT Tue Apr 07 2020/ Today and Tonight. Current satellite imagery & RAP mesoanalysis depict an area of mostly elevated convection across Central MS along & north of a theta- e boundary, which is generally sliding eastward/northeastward with time. South of this boundary, surface-based instability can be found to ~1,000 J/kg as dewpoints in the upper 60s to around 70 have spread north of I-10 amidst favorable low-level warm/moist advection. With resultant isentropic ascent over much of the area, cloudy skies and increasing rain chances from the west remain the general theme for much of Central Alabama this afternoon as we climb into the mid 70s to lower 80s. Exceptions to this will be areas remaining rain-cooled during peak heating hours across the west. As the boundary continues northeastward this afternoon, a limited opportunity for a strong to severe thunderstorm may exist across our southwest counties - quarter size hail and/or a damaging wind gust in stronger storms cannot be ruled out. Best chances remain along and south of a line from Pickensville to Selma, and will be contingent on positioning of the boundary later this afternoon, and if any more robust updrafts can take advantage. Once diurnal heating is lost, convective trends are expected to weaken. This is important to remember as the boundary becomes more diffuse while continuing northward overnight, though isolated to scattered showers and thunderstorms remain possible into tomorrow morning as a warm/moist tropical airmass overspreads much of the Gulf Coast Region. Tomorrow afternoon. A summer-like, humid airmass is forecast to take over Central Alabama tomorrow afternoon. Dewpoints in the upper 60s to lower 70s appear probable, with forecast soundings suggesting mid-level lapse rates 6.5-7 C/km. This is setting the stage for 3,000-4,000 SBCAPE amidst eff. bulk shear 50-60 kts. This suggests severe weather given we hang on to favorable deep-layer shear profiles & good low-level moisture, though effects from ridging and lack of a distinct lifting mechanism are big limiting factors in specific timing and areas of higher risk. Regardless, any mesoscale boundary left around from tonight`s rainfall could provide just enough boost to expected low-level lapse rates ~8-9 C/km and air just below convective temperatures such that isolated to scattered storms may initiate. This notion will be watched closely as recent CAMs suggest thunderstorms developing ~21 Z, though we may not be able to pin down a specific threat area until tomorrow morning when satellite imagery & surface obs help detect smaller- scale boundaries/features. Chance PoPs are being maintained as a broad theme, with an area-wide `Marginal Risk` being introduced in the HWO for the afternoon/evening severe threat. The potential thermodynamic environment tomorrow afternoon suggests capability for robust updrafts containing damaging winds up to 60 mph (given DCAPE 800-1,200 J/kg and LIs -7 to -9 C), as well as quarter size (possibly larger) hail. The next 36 hours will be a fluid forecast situation given a wide range of solutions in guidance, as well as the two possible rounds of severe weather tomorrow (one in the afternoon/evening, another possible overnight and into Thursday morning along a frontal boundary). Each preceding event will have impacts on subsequent environments, boundaries, and associated thunderstorm activity. Central AL residents should check back for upcoming forecast updates. 40/Sizemore .LONG TERM... /Updated at 0231 PM CDT Tue Apr 07 2020/ Wednesday night through Monday. Diurnal convection from Wednesday afternoon storms will linger into the evening hours. Severe threat will also carry over into the evening hours, but storm strength should weaken considerably by 9 pm due to loss of daytime heating. There should be a lull in thunderstorm activity between 9 pm Wednesday and 3 am Thursday. A strong cold front will approach northwest Alabama late Wednesday night and push through central Alabama Thursday morning. Models are all over the place with respect to areal coverage and mode of convection. There could be a broken line of strong to severe storms or possibly more discrete cells. A wide range of instability also noted among the models with 06z Thursday CAPE values ranging from 500 to 2500 J/kg just ahead of the cold front. Dry air aloft will produce DCAPE values above 1000 J/kg and steep mid level lapse rates for the production of large hail. The northwest counties will have a higher threat for severe storms and upgraded these counties to a slight risk category. The storms should weaken by 9 am Thursday as the convective cold pool outruns the better instability. Only isolated storms expected for areas south of I-20 Thursday afternoon. Much cooler and drier air will move in behind cold front. Lows Friday morning will be in the middle to upper 40s across the northern counties with lower 50s elsewhere. The cooler weather will continue through Saturday morning with highs Friday in the middle 60s to lower 70s, and lows Saturday morning in the upper 30s to middle 40s. Long range models have slowed down arrival on rain ahead of weekend system, and lowered rain chances for Saturday. A low latitude storm system will eject out of the Southern Plains states over the weekend. There are still timing and evolution issues with this system, but it bears watching for severe potential. 58/rose && .AVIATION... 00Z TAF Discussion. Light rain showers have moved across Central Alabama the past few hours. This activity will linger for a fro more hours and then gradually lose coverage. The rain remains in the forecast throughout in some manner. There will be a chance of thunder on Wednesday afternoon. Ceilings start off VFR will a trend to LIFR before 12z at all locations. Vis looks to remain in the 4-6sm range. The lower ceilings improve 16-18z. 75 && .FIRE WEATHER... Showers and thunderstorms move into Central Alabama today as a boundary spreads from west to east across the area. Minimum relative humidity values are expected to remain above 40 percent through Wednesday. This is due to a warm, humid airmass expected tomorrow afternoon with strong to severe thunderstorms possible into Thursday morning. Thereafter, a front will bring drier and cooler conditions for Thursday and Friday. However, rain chances return for the weekend as another system approaches. && .PRELIMINARY POINT TEMPS/POPS... Gadsden 61 82 62 73 44 / 60 40 50 20 10 Anniston 62 82 64 75 46 / 60 40 40 30 10 Birmingham 64 83 66 75 49 / 60 40 50 30 10 Tuscaloosa 66 85 66 78 49 / 50 40 40 30 10 Calera 64 82 66 76 49 / 60 50 40 30 10 Auburn 64 80 66 80 51 / 60 50 20 30 10 Montgomery 67 84 67 82 53 / 50 50 10 30 20 Troy 68 83 68 84 54 / 50 50 10 20 20 && .BMX WATCHES/WARNINGS/ADVISORIES/... None. && $$
Area Forecast Discussion
National Weather Service Boston/Norton MA
1007 PM EDT Tue Apr 7 2020 .SYNOPSIS... High pressure in place will give way to a weak area of low pressure moving in from the Great Lakes. This low pressure will spread a period of rains later tonight into early Wednesday as it moves into the waters south of New England. Another system moves in Thursday, bringing more rain and scattered thunderstorms. Scattered showers are possible Thursday night through Friday. Drier weather for this weekend before our next wet weather system early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1005 PM update ... Previous forecast verifying nicely with current and upstream observations along with radar and satellite trends. Thus no major changes with this forecast update. Previous Discussion... The primary feature of interest for much of the night, however, is a NW to SE oriented and rather well-defined warm front associated with a low pressure area as of early this afternoon near northern Michigan. The low and its related warm front will progress east- southeast through the northern mid-Atlantic region into Southern New England later tonight, with increasing clouds through midnight and rains spreading east-northeastward especially for the overnight hours. Temperatures look to remain mild enough even across the terrain to stay as rain. However worth noting the thermal contrast through the warm front is fairly robust, and in addition to that, I did notice on SPC`s mesoanalysis page a plume of weak mid-level instability (700-500 mb lapse rates ~6-7 C/km) even on the north side of the warm front. Some guidance - most notably the NAM and the RAP - brings a sliver of this weak elevated instability into a part of northern CT into central/southern RI and the south coastal waters overnight tonight (roughly from a South Windsor to Putnam CT to Coventry RI line). Though rain should predominate, I did opt to include some isolated thunder (basically rumbles) along and south of this line. Rains should continue into the Wednesday morning for most. Model guidance QPF off today`s 12z guidance was a bit greater than previous runs. Opted for rain totals thru 12z Wednesday from a quarter to third of an inch for southern RI into the Hartford area, then tapering to a tenth to two-tenths of an inch further north and east. Lows tonight mainly in the mid-upper 30s to the lower-mid 40s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Wednesday: Weak low pressure and attendant warm frontal-related showers pass south of the coastal waters through the morning hours. As these features pass to our south, likely to see a modest uptick in NE wind speeds into the morning hrs and especially near the eastern MA coast (indicated by the NAM 975 mb winds which tick up to around 25-kt just offshore). Eventually these winds will lighten and shift to easterly moving into the afternoon. Some gradual improvement with rains coming to an end by late- morning/early afternoon (latest towards Cape Cod and the offshore waters), and skies trending mostly to partly cloudy. So the second half of the day is looking somewhat better than the first half, but with NE to E onshore flow and a shorter period of sun, I opted to keep temperatures on the cooler side of guidance, into the upper 40s to the mid 50s. Wednesday Night: Weak shortwave ridging/modest 500 mb height rises, ahead of a strong frontal system to affect our area into Thursday, should allow for dry conditions through the first part of the overnight. Model guidance shows moisture levels starting to rise on SE flow into the second half of the night, with increasing clouds spreading from west to east. In addition, 500 mb height falls then spread into western MA into northern CT into the early morning hrs. PoPs increasing to chance type levels for these locations though most should stay dry. Lows mainly into the upper 30s to mid 40s with modest SE breezes. && .LONG TERM /THURSDAY THROUGH TUESDAY/... * Widespread rain Thursday with scattered thunderstorms * Lighter rain, and high elevation snow possible, on Friday with a few rumbles of thunder also possible * Potential for minor coastal flooding Wednesday to Friday around high tide across the east and south coasts of MA and RI. See the Tides and Coastal Flooding section below for more details. * Temperatures running near to below normal through Saturday, then a warm up Thursday... This still appears to be the most active weather day during this portion of the forecast. Potent mid level low shifts over northern New England, with a low pressure passing through our region. Almost certainly looking at some rain for much of southern New England, with some wet snow possible across the higher terrain. Drier air rushes in behind the cold front of this system, drying our the forecast into Friday. As for thunderstorm potential, surface-based instability is not the best. However, mid level lapse rates are better than moist adiabatic with a strong low-level jet from the south. These factors are enough to warrant at least a mention of isolated thunderstorms. Still too early to say if any of these thunderstorms could be severe. Friday... Low pressure continues to rotate away from our region. Still in the cyclonic flow, so cannot dismiss the idea of a few showers during the day, rain for most with snow possible across the higher terrain. Saturday through Sunday... The weekend looks drier as a ridge of high pressure makes its way east across the Mid Atlantic states. This should mean a warming trend into Sunday. Monday into Tuesday... Another low pressure should move across the Great Lakes, leading to another round of showers sometime from Monday afternoon into Tuesday morning. Timing is not yet locked down. Looking warm enough for all rain. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 02z update ... no major changes from previous TAFs. Earlier discussion below. ============================================================= Tonight: High confidence in trends, moderate on timing. Increasing/lowering clouds associated with a warm front which will eventually spread rains across the TAFs. Initial VFR with deterioration to MVFR ceilings (possible IFR ceilings south of BDL to PVD to the Cape airports) after 08/05-07Z with VFR-MVFR vsby rains spreading ESE through 08/08-12Z. Due to the dry air around, timing is a bit uncertain but could be an hour or two sooner than indicated in the TAFs. Through midnight, mainly light/variable winds in the interior, SE 5-8 kt towards the Cape and at BOS. After midnight through 08/12Z, winds to shift to NE around 5-10 kt as front slides S of the coastal waters. Wednesday: High confidence in trends, moderate on timing. Initial MVFR, possible IFR with periods of rain to generally taper off through the morning. Gradual improvement from widespread MVFR to MVFR/VFR levels toward the afternoon. NE/ENE winds 4-8 kt in the interior, around 7-10 kt with occasional gusts to 20 kt coastal MA and the Cape. Wednesday Night: Moderate to high confidence. Increasing moisture levels on SE flow will result in VFR-MVFR ceilings lowering to MVFR-IFR levels in the interior and across the higher terrain. For the coastal plain into the Cape, initial VFR to trend VFR/MVFR into the pre-dawn hrs. Rains should hold off until the pre-dawn hrs in the CT Valley with dry conditions elsewhere. SE winds 6-10 kt. KBOS Terminal...High confidence in the TAF. KBDL Terminal...High confidence in the TAF. Outlook /Thursday through Sunday/... Thursday: MVFR/IFR conditions possible. Windy with gusts up to 30 kt. Chance SHRA, isolated TSRA, patchy FG. Thursday Night: VFR. Windy with gusts up to 35 kt. Friday: VFR. Windy with gusts up to 30 kt. Slight chance SHRA. Friday Night through Saturday: VFR. Breezy. Saturday Night: VFR. Sunday: VFR. Slight chance SHRA. && .MARINE... Winds and seas should remain below SCA thresholds through Wednesday night. A warm front will bring a period of steady rains for most of the waters late tonight into Wednesday morning, with an outside/low chance for a rumble or two of thunder across the southern offshore waters overnight. Could see vsbys between 3-5 SM in rains, likely lowest south coastal waters. Winds to become NE on Wed AM, and could briefly reach marginal-SCA gusts with seas 3-4` (near 5` per the SWAN guidance off the NAM) on the eastern MA/Cape Cod waters. Wasn`t confident enough on criteria being met to issue an SCA for these waters Wed AM, but may get close. Winds lighten to under 20 kt and shift east later Wednesday and then SE into Wednesday night. Seas mainly 2-3` Wednesday night, though build to 2-4` by daybreak. Outlook /Thursday through Sunday/... Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers, isolated thunderstorms, patchy fog. Local visibility 1 to 3 nm. Thursday Night: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 10 ft. Friday: Strong winds with gusts up to 30 kt. Rough seas up to 12 ft. Slight chance of rain showers. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Saturday: Winds less than 25 kt. Local rough seas. Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Sunday: Winds less than 25 kt. && .TIDES/COASTAL FLOODING... 418 PM Update: Astronomical tides are on the rise over the next several days (across multiple tidal cycles) due to the Supermoon. While the overall threat is limited by poor wave action, due to the high astro tides a number of tidal gages are forecast to be near flood stage or into minor flooding categories per Stevens Institute guidance. Appears the greater potential for minor coastal flooding later tonight into Wednesday should exist for eastern coastal MA and Cape Cod/Nantucket, especially around the period of high tides. By Wednesday night into Thursday, stronger southerly winds ahead of a strong frontal system will raise the coastal flood threat across a larger area to include the South Coast and Narragansett Bay. Coastal Flood Advisories have been posted thru Friday following these general expectations. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Coastal Flood Advisory from 8 AM Wednesday to 8 AM EDT Friday for MAZ019-022. Coastal Flood Advisory from 8 PM Wednesday to 8 AM EDT Friday for MAZ015-016. Coastal Flood Advisory until 8 AM EDT Friday for MAZ007. RI...Coastal Flood Advisory from 8 PM Wednesday to 8 AM EDT Friday for RIZ002-004>007. MARINE...Gale Watch from Thursday afternoon through Friday afternoon for ANZ231-232-250-251-254-255. && $$ SYNOPSIS...Belk/Loconto NEAR TERM...Belk/Loconto SHORT TERM...Nocera/Loconto LONG TERM...Belk AVIATION...Belk/Nocera/Loconto MARINE...Belk/Loconto TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Dodge City KS
1035 PM CDT Tue Apr 7 2020 ...Updated Aviation... .SHORT TERM...(This evening through Wednesday) Issued at 248 PM CDT Tue Apr 7 2020 Warmer today with 85 degrees already at 2 pm. The northwest winds that are gusting now to around 25 mph should slowly being to weaken per hourly HRRR wind fields and as the surface winds slowly veer easterly with time into the late afternoon. Wind will become light southeasterly this evening before flipping northwest again by later Thursday morning. Overall a mild night again across the forecast area with lows in the 40s and 50s, west to east. .LONG TERM...(Wednesday night through Tuesday) Issued at 248 PM CDT Tue Apr 7 2020 A slowly progressive pattern is developing on the synoptic scale, as a large 500 mb low rotating off the southern California coast moves across the sw US and Mexican border, weakening to and open wave over the central and southern High plains region by late this weekend. For the timeline, initially on Wednesday we will see no impacts from this system as a weak cold front enters Kansas with the best cold advection coming late in the day or evening, when temperature falls actually become more noticeable. By Thursday, cooler highs in the 60s as the surface winds spends the day veering northeast to south again by the Thursday evening timeframe and the surface ridge settles into the southern Mississippi valley by Friday. Sometime Friday into late Saturday has the best potential for thunderstorms produced from any potential surge of theta-e advection. Looking farther into the weekend and early next week, we see increasing confidence in quite cold boundary layer air returning and 850 mb temperatures as cold as -9C diving across Kansas and points south. With the wave moving across the region at the time, forecasting a period of rain and possible rain changing over to snow at some point will become the mesoscale forecast challenge Sunday into Monday. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1035 PM CDT Tue Apr 7 2020 VFR/SKC expected through this TAF forecast cycle. Light and variable winds overnight will trend northerly after sunrise/ 12z Wed. After 15z Wed, north winds will increase behind an advancing cold front. Expect north wind gusts of 25-30 kts at all airports Wednesday midday/afternoon, with winds trending NEly and diminishing around sunset/00z Thu. && .PRELIMINARY POINT TEMPS/POPS... DDC 50 77 37 60 / 0 0 0 0 GCK 47 76 35 60 / 0 0 10 0 EHA 47 78 38 63 / 0 0 10 0 LBL 48 78 36 62 / 0 0 10 0 HYS 46 77 36 57 / 0 0 0 0 P28 52 81 40 63 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Turner
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
635 PM CDT Tue Apr 7 2020 .AVIATION... VFR conditions prevail across the area with some low clouds remaining around the San Antonio sites. Models have come in a bit more optimistic this evening regarding ceilings and visibility by morning. Didn`t go quite as optimistic as the new guidance and went with more of a blend between the old TAFs and the new guidance. Think we will likely see BKN ceilings with some breaks in the clouds possible. In addition, some visibility restrictions are possible. VFR conditions should return by the early afternoon. For the afternoon, scattered convection is possible with initiation first occurring in the Hill Country. If the storms do develop, they would then move east and potentially impact the I35 sites in the late afternoon or evening hours. && .PREV DISCUSSION... /ISSUED 253 PM CDT Tue Apr 7 2020/ SHORT TERM (Tonight through Wednesday Night)... High dew point temperatures in the upper 60s to mid 70s are holding back afternoon temps despite partly to mostly sunny skies. Shortwave ridging in the mid levels of the atmosphere will keep most of the area rain free this afternoon and evening, but the GFS is matching recent runs of the HRRR to suggest a weak mid-level impulse will trigger topography based convection later in the evening into the overnight hours. This should only result in a isolated storm or two that could briefly become strong over the Serranias del Burros, but should move into well-capped low levels and be quick to weaken as they reach the Rio Grande. Low clouds and a few patches of light fog are possible tonight, but there should be much less of the visibility restrictions after a abundant sunshine provided deep mixing in the low levels. Dew points in the upper 60s and low 70s overnight are expected to cover all but perhaps NW Val Verde county tonight and possibly set the table for a strong to severe storm environment late Wednesday. Another hot and humid day starts of Wednesday with high dewpoints in the low to mid 70s correlating with Pwat values of 1.5 to 1.8 inches. Westerly winds in the low to mid levels of the atmosphere over North Central and West Central Texas are expected to develop the focus for afternoon convection, the eastward shift of a dryline into the Hill Country. At maximum heating, the various HREF members suggest a potential for CAPES to approach 4000 J/Kg should the right environment come together. Boundary layer winds in the near storm environment should be mostly out of the SW, so this will curb shear profiles some, making for mainly speed shear. But 3-4 KJ/Kg in March should be good enough to favor a favor isolated supercells capable of very large hail over 2 inches and damaging winds. SPC has recognized the escalated threat and responded in kind with an upgrade from marginal to slight risk in the day 2 outlook. The storm severity could carry well into the mid-evening hours, but the lack of heating later, should translate to weakening storms in the late evening. Cell coverage should initially be isolated through the late afternoon, with perhaps 30 to 50 percent coverage developing with cell-mergers and small scale squall lines later in the evening. At this time, we are not expecting a significant influence on the surface weather pattern in terms of boundaries, as more rain and storm chances arrive early in the extended periods. LONG TERM (Thursday through Tuesday)... The combination of a moving dry-line into the Rio Grande Plains area and a shallow cold front pushing across South Central Texas on Thursday is expected to bring scattered to numerous showers and isolated thunderstorms. The frontal boundary will continue to push away from the area into the Gulf coastal waters in the late afternoon and evening. Some storms could be strong to severe as the cold front moves along and to areas east of Interstate 35 during the afternoon period. Large hail and damaging winds are the primary threats. With the frontal boundary well to the southeast of our area for the Thursday night into the Friday morning, decided to go with only 20 percent chance for rain for the far east part of the region. However, the dry weather conditions won`t last long since another round of showers and thunderstorms is forecast for late Friday afternoon into Saturday. A weak warm front is forecast to move into the area while an upper level low pressure system and associated Pacific front move across the region. Can`t rule out a few strong to severe storm as the Pacific front moves along and to the southeast of the I-35 corridor during the Saturday morning time frame. Isolated pockets of 1 to 2 inches of rainfall are expected from Friday afternoon into Saturday afternoon. Can`t rule out a few spots getting up to 3 inches. All of this depends on how quickly the front moves out from the area. Dry weather is expected for Sunday with highs in the 80s for the most parts followed by a dry and cooler Monday and Tuesday with highs in the 60s and lower 70s as a polar front makes it down to the area. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 71 91 68 80 59 / - 30 30 60 20 Austin Bergstrom Intl Airport 70 91 67 81 59 / - 30 30 60 20 New Braunfels Muni Airport 70 90 67 82 60 / - 20 30 60 20 Burnet Muni Airport 69 89 66 77 55 / 10 20 20 50 20 Del Rio Intl Airport 70 92 70 87 63 / 20 20 10 20 10 Georgetown Muni Airport 71 91 66 78 57 / - 20 20 50 20 Hondo Muni Airport 69 91 68 85 60 / 20 30 30 50 20 San Marcos Muni Airport 69 90 67 82 59 / - 20 30 60 20 La Grange - Fayette Regional 71 90 69 83 61 / 0 20 20 60 40 San Antonio Intl Airport 71 91 69 83 61 / 10 20 30 60 20 Stinson Muni Airport 70 91 69 85 62 / 10 20 30 50 20 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term/Aviation...Hampshire Long-Term...KCW
Area Forecast Discussion
National Weather Service Goodland KS
835 PM MDT Tue Apr 7 2020 .UPDATE... Issued at 830 PM MDT Tue Apr 7 2020 There appears to be a 3 to 4 hour window for a few showers and possible thunderstorms to develop, generally 06-10z in the vicinity of the Kansas Nebraska border. In this area sufficient moisture in the 700-500mb layer coupled with 100-200 J/KG of CAPE around 2KM and some convergence at 850mb between a weak low level jet nosing in from the south and northwest winds approaching from the northwest. 00z NAM and 23z/00z HRRR painting some light qpf in this area. Otherwise made some minor adjustments to all other parameters through Wednesday. && .SHORT TERM...(This evening through Thursday night) Issued at 233 PM MDT Tue Apr 7 2020 The main short term forecast concern is the possibility of elevated fire weather conditions ahead of a cold front on Wednesday. Warmer than normal temperatures of the past couple days turn cooler on Wednesday and Thursday following the passage of a cold front during the day on Wednesday. Ahead of this cold front dry conditions remain in place over mainly far eastern Colorado where relative humidity values between 15-20 percent persist. Winds are expected to turn north and increase during the day with gusts of 30-35 mph, which will bring conditions to near critical fire weather values over a small portion of the far southwest corner of the forecast area. Do not expect to need a fire weather highlight at this time. No precipitation is expected with this front. Low temperatures will be back down in the 30s Wednesday night with daytime highs only reaching the the upper 50s to lower 60s on Thursday. The cooler temperatures will bring minimum afternoon relative humidity values back up into the 20-35 percent range with overnight relative humidity values recovering into the 70-85 percent range. .LONG TERM...(Friday through Tuesday) Issued at 215 PM MDT Tue Apr 7 2020 Will manage one more warm and dry day on Friday under shortwave ridging, but precipitation chances begin Friday night and continue through the remainder of the period. Best chances for precipitation will be Sunday, when an inch or two of light snow will be possible, as a large trough digs into the northern and central High Plains. Expecting windy conditions to accompany the light snow as well, with current model projections suggesting north winds gusting 40-50 mph by Sunday afternoon. Given the light snowfall amounts and warm ground temperatures which will result in considerable melting, not expecting blowing or drifting to be a problem at this time. Beyond Sunday, will be under a northwest flow with much below normal temperatures. Model POPs appear a bit overdone, but cannot rule out weak disturbances in the northwest flow resulting in rain/snow showers early next week. Low temperatures will reach the teens Monday morning, and the teens and 20s Tuesday morning, so agricultural and ranching interests need to be prepared for the colder temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 500 PM MDT Tue Apr 7 2020 For KGLD and KMCK, vfr conditions through the period. Winds at both sites will generally be variable at speeds under 6kts through 09z or so before establishing a westerly component under 10kts through 14z or so as a cold front is about to move through the area. This front is expected to produce north and northwest winds gusting up to around 30kts through the late morning and afternoon hours. KGLD may lose the gusts around 23z but remain just above 12kts. No precipitation is expected. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...99 SHORT TERM...LOCKHART LONG TERM...024 AVIATION...99
National Weather Service Wilmington OH
946 PM EDT Tue Apr 7 2020 .SYNOPSIS... A warm front north of the area will keep an influx of more moist and unstable air over the Ohio Valley tonight. Thunderstorms, some severe, are forecast to sweep through the area overnight with the passage of a cold front. A brief period of high pressure and dry weather on Wednesday will be followed by another more potent cold front Wednesday night containing additional showers and thunderstorms. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Current surface analysis indicates that low pressure is moving ESE across southern Michigan, with widespread strong to severe convection running south of / ahead of the low from Port Huron MI to Chicago IL. The warm sector in place to the south of this low is currently free of storms or any signs of convective development, capped by quite a bit of warm air located at about 750mb. Current conditions within the warm sector (across IN/OH) are characterized by SW winds, temperatures in the upper 60s to lower 70s, and dewpoints in the mid 50s to around 60. The main focus for tonight is on the potential for severe thunderstorms, as the aforementioned convection moves southwest through Indiana and Ohio. There appears to be a well-defined wind shift and theta-e boundary in the lower levels that will move southwest, crossing through the ILN forecast area between 06Z-12Z, with storms generally focused ahead of it. Upper level support for convection is not as impressive, with generally broad ridging aloft, and no obvious signs of large-scale vorticity advection. Thus, the forcing part of the equation for tonight is mixed -- favorable in the low levels, and not so much aloft. A westerly LLJ is expected to develop across Indiana in the 00Z-06Z time frame, providing a surge of warmth and moisture into the boundary layer, which should keep conditions favorable for additional thunderstorm development as the evening turns into the overnight. The key factor for tonight is instability, with high confidence (now supported by the 00Z KILN sounding) in very steep lapse rates aloft. The evening sounding indicated 700mb-500mb lapse rates of 7.4 degrees C/km, and several models are indicating that these mid-level lapse rates may exceed 8.0 degrees C/km in the next few hours across the northern / northwestern sections of the ILN forecast area. When looking at projections of CAPE, it is interesting to note that the CAPE from a lifted parcel is arranged a little differently on the sounding than might be normal -- the majority of the instability (and the greatest separation from atmospheric temperature to parcel) is focused high in the troposphere, within a zone where hail growth is favored. Deep-layer wind shear is also impressive enough to allow for storm organization (supercells / clusters) which will further enhance the threat for hail. This forecast is in agreement with the SPC D1 outlook, which indicates the potential for significant hail. There are also a couple of limiting factors that should be discussed. First off, there are some concerns with storm coverage, especially on the western periphery of the developing convective system. The last few runs of the HRRR have been quite meager with the western extent of convection. However, not too much attention is being paid to this solution -- current upstream radar imagery and the expected theta-e surge (mentioned above) would suggest that convective development is more likely than not to continue across much of the CWA -- especially the northern half. Second off, there are some concerns with boundary layer stability, which can be assessed to some degree by looking at surface dewpoints. Most of the model projections (sans the NAM which is well too moist) suggest that dewpoints in the ILN CWA will increase from the mid 50s to the lower 60s over the next few hours. It remains to be seen if dewpoint advection will be strong enough to do this. The expected vertical profile ahead of the storms will likely feature only marginal lapse rates in the lowest few thousand feet, topped (as mentioned) by very steep lapse rates further aloft. Any marginal lapse rates near the surface, and any remnant of the cap that sticks around, would work to significantly limit the threat for convective wind. If these storms congeal into more of a cold-pool driven MCS, the wind threat would obviously increase. As a final note -- 0-1km shear orientation and magnitude, combined with the issues of boundary layer stability, would suggest that the tornado threat for this event is not particularly high. Severe Thunderstorm Watch 84 is now in effect for the northern three ILN counties, and additional watch issuance further south may be needed. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Cold pool stratus trailing the storms from earlier overnight will break up in the morning from northwest to southeast as drier air works in with high pressure to the north. Upper level height fields drop off slightly and the more traditional cold front with the tiniest of recoveries on Thursday or a steady/slow drop in readings through the day is expected with upper level support reinforcing the cold advection beyond this period. Showers and possibly a few thunderstorms over the southern portions of the CWA are possible overnight as the next front crosses tomorrow night, beginning towards midnight in the northwest and exiting by daybreak in the southeast. Highs Wednesday will be in the upper 60s to lower 70s, with overnight lows ranging from near 40 in the northwest to near 50 in the southeast. && .LONG TERM /THURSDAY THROUGH TUESDAY/... We could see a few lingering showers across our far southeast Thursday morning but with the cold front moving off to our southeast, expect mainly dry conditions through the day. In decent CAA through the day, temperatures will likely not recover too much with highs ranging from the mid 40s northwest to possibly mid 50s across the southeast. The CAA and a fairly tight pressure gradient will also lead to some gusty winds through the day. Surface high pressure will build east across the Ohio Valley Thursday night through Friday night, leading to dry but seasonably cool conditions. Lows Thursday night will be down into the mid 30s but think winds may stay up enough to help limit frost development. Highs on Friday will generally be in the 40s. Lows Friday night will be in the low 30s and with lighter winds, it looks like a better chance for some frost. This will be somewhat dependent though on how fast clouds possibly move in later Friday night/early Saturday morning. Mid level short wave energy will lift out of the Southern Plains and across the lower Ohio Valley Saturday into Sunday. This will help carve out a broader trough across the central US through early to mid next week. Models differ on their timing/placement and strength of an associated surface low that will lift northeast across the eastern US/possibly Great Lakes region Sunday into Monday. This will lead to an increasing chance of showers and perhaps a thunderstorm through the later half of the weekend. Will allow for a gradual increase in pops heading into Sunday/Sunday night, but mostly limit them to high likely or chance given some of the uncertainty. For that same reason, will linger some slight chance pops on into Tuesday. Temperatures (and winds) through this time period will also be dependent on the strength/track of the low. Have trended toward the model blend for temps (and consall for winds). && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... VFR conditions will continue for the start of the TAF period, with gusty WSW winds. Going into the overnight hours, the main concern will be for thunderstorms to move in from the north. Some of these storms may be severe, so strong winds and hail are a possibility -- along with IFR conditions. The most likely timing for storms will be in the 05Z-08Z time frame for KDAY/KCMH/KLCK/KILN and a couple hours later for KCVG/KLUK. After the storms depart, winds will shift to the northwest, and a period of MVFR ceilings is expected for most locations. However, confidence is not particularly high in the ceiling forecast, and some areas may stay mainly VFR. At any rate, by 15Z, VFR conditions are expected again with clearing skies. Very little weather of consequence is expected through the daytime hours tomorrow, with NW winds at or below 10 knots, and VFR conditions. The next chance for showers and storms will move in after the end of the TAF period. OUTLOOK...Thunderstorms are possible Wednesday night. MVFR conditions are possible Wednesday night through Thursday morning. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Franks NEAR TERM...Hatzos SHORT TERM...Franks LONG TERM...Sites AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Lincoln IL
915 PM CDT Tue Apr 7 2020 .SYNOPSIS... Issued at 905 PM CDT Tue Apr 7 2020 Widely scattered thunderstorms will be possible tonight, mainly along and north of the I-74 corridor. Overnight lows will range from the lower 50s from the Peoria area the lower 60s south of I-70. && .UPDATE... Issued at 915 PM CDT Tue Apr 7 2020 A broken line of convection has developed along a slow-moving cold front extending from the Chicago metro westward into central Iowa. CAMs have not been adequately catching the storm development on the western end of the front across Iowa, making short-term forecasting a bit challenging. Latest mesoanalysis continues to show a moderately unstable airmass south of the boundary across central Illinois, characterized by MLCAPEs of around 1500J/kg. 0-6km bulk shear values decrease further south, but are still an appreciable 40-50kt across the area. Main mitigating factor for storms continues to be mid-level capping in the warm sector, although that has been gradually weakening this evening. Given current radar trends, think the storms along the front will slowly weaken with time as they track E/SE into the more unfavorable airmass further south. Have adjusted PoPs to carry low chance along/north of the I-74 corridor for the next few hours, then continued just slight chance PoPs across the eastern KILX CWA after midnight in case an isolated shower/storm can develop along the front as it sinks further southward. && .SHORT TERM...(This evening through Wednesday night) ISSUED AT 325 PM CDT Tue Apr 7 2020 Clouds cleared out this afternoon amid a capping layer at 850 mb, and limited low level moisture. The cold front will come into an area of substantial elevated instability (2500 J/kg MLCAPE), with potential for some strong updrafts after the warm layer aloft erodes ahead of the cold front. However, HRRR and RAP updates are showing very isolated showers/storms in our forecast area this evening, most likely attributed to the lack of moisture. We have reduced PoPs early this evening to slight chance, but ramp up to Chance in our east-southeast counties later this evening, lingering through 3-4 am south of I-70. The front does appear poised to energize a bit farther to the southeast toward Taylorville and Shelbyville later this evening, so we did continue chance PoPs that far west. Confidence on coverage of storms tonight is low, but the Slight Risk east of Bloomington to Decatur indicates the potential for large hail should any storms develop in that area this evening. The next point of concern is the potential for severe storms again with the stronger cold front Wed afternoon into evening. Once again, deep layer moisture will be limited, and MLCAPE instability will be lower, in the 800-1200 J/kg range. However, wind shear will be in the 60-70kt range, and there appear to be pockets of strong vorticity along the boundary. SPC`s 17z updated expanded the Slight Risk northward all the way to I-74, for large hail and damaging winds. It was previously limited to south of I-70. Deterministic models are showing higher QPF potential, so have gone with the likely/categorical PoPs ahead of the front. The front will be moving quickly through the area, with forward motion of 45-50 mph. That will aid in producing enhanced updrafts as well. .LONG TERM...(Thursday through Tuesday) ISSUED AT 325 PM CDT Tue Apr 7 2020 Strong northwest winds will highlight Thursday, with sustained winds in the 20-25 mph range, just below advisory criteria (30 mph). Gusts will reach over 40 mph at times, especially in the afternoon. Mixing heights look to reach up to 5-7K FT, tapping into 40-45 KT winds. So despite ample sunshine on Thursday, high temps will struggle to reach the lower 50s, or 20-25 degrees cooler than Wednesday. Winds will not be as strong on Friday, in the 15-20 mph range, but chilly highs in upper 40s to low 50s will continue one more day. Saturday will see increasing rain chances north of I-70 as a warm front develops across NW Illinois. Southerly winds will bring increasing moisture and slightly warmer temps. Highs will reach into the mid to upper 50s under a showery day. Rain chances will diminish only briefly Saturday night as a surface low pressure center progresses from Oklahoma to Kentucky on Sunday. Rain chances will increase to Likely Sunday south of I-72/Danville, but thunder potential will be minimal. An unfortunate result of that low passage will be colder air being pulled into Illinois for Monday and Tuesday. Overnight lows will dip below zero both nights, with a few flakes of snow not out of the question Monday night for areas N of I-72/Danville. The models tend to have a problem modifying sufficiently in response to the warmer ground in place ahead of that system this time of year, so there will likely be warming air mass temps as the models catch up to a more likely scenario. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 644 PM CDT Tue Apr 7 2020 VFR conditions will prevail through the entire 00z TAF period. A cold front currently extending from southern Wisconsin into central Iowa will sag southward tonight...reaching the I-72 corridor shortly after midnight. Isolated thunderstorms will be possible along the boundary: however, most model solutions keep the activity N/NE of the terminals. Have included VCTS at KPIA/KBMI/MCMI between 03z and 07z in case a few cells develop this far W/SW along the front before diminishing overnight. Further south, have kept the remaining TAF sites completely dry. Winds will initially be SW with gusts of around 20kt this evening, then will veer to W and decrease to 10kt or less as the front approaches. Once the boundary passes, light NW winds are expected late tonight into Wednesday morning. Winds will once again swing around to the S/SW late Wednesday as a stronger cold front approaches from the northwest. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SYNOPSIS...Barnes SHORT TERM...Shimon LONG TERM...Shimon AVIATION...Barnes
Area Forecast Discussion
National Weather Service Indianapolis IN
Issued by National Weather Service Bismarck ND 1043 PM EDT Tue Apr 7 2020 .UPDATE... The NEAR TERM and AVIATION Sections have been updated below. && .SYNOPSIS... Issued at 438 PM EDT Tue Apr 7 2020 Severe thunderstorms are possible across the area tonight as a weak cold front passes through the region. Wednesday will be warm again ahead of another front that will arrive on Wednesday night with a more widespread area of showers and thunderstorms. A few severe thunderstorms are possible again Wednesday night. Breezy and much cooler weather will arrive Thursday and Friday. && .NEAR TERM /Rest of Tonight/... Issued at 1032 PM EDT Tue Apr 7 2020 A line of strong to severe storms has made it`s way into northern Indiana and will continue to sag south and east over the next few hours. The last few iterations of the HRRR seem to have a pretty good handle on the ongoing convection and would have the strongest part of the line giving the north central and northeastern portions of the forecast area a glancing blow. Further development continues across western Illinois and eastern Iowa but it is still pretty uncertain whether this activity will be able sustain itself until it reaches our area. For this reason, cut back on precipitation chances across much of our south, west, and portions of the central. Otherwise, the forecast looks to be in good shape. && .SHORT TERM /Wednesday through Thursday Night/... Issued at 438 PM EDT Tue Apr 7 2020 Low- and midlevel warm air advection will quickly resume Wednesday as another, stronger shortwave trough amplifies in the upper Great Lakes. Post-frontal drying behind tonight`s system is forecast to be significant enough to stunt return-flow trajectories Wednesday in advance of the next and stronger cold front expected to arrive Wednesday night, so the expected instability with the next front will be lower, with MLCAPE generally in the 500 to perhaps 1000 J/kg range. However, forcing for ascent will be stronger and the 12 UTC model suite and related NBM guidance supported PoPs in the 70-90 percent range Wednesday night, and strong wind fields are supportive of a few severe storms, as well. It will be warm again Wednesday ahead of the secondary cold front with NBM-driven forecast highs in the 70s again. On Thursday, cold air advection will rule with forecast highs falling into the 45 to 55 F range with gusty northwest winds. Low-level momentum transfer in the cold air advection regime will likely support winds more in line with MOS-based forecast guidance, so the official forecast was weighted toward those numbers. Winds could remain elevated enough on Thursday night behind another, reinforcing cold frontal zone to prevent frost formation in most areas, but actual lows are forecast to reach the lower and middle 30s F in many areas. && .LONG TERM /Friday through Tuesday/... Issued at 438 PM EDT Tue Apr 7 2020 A cool weather pattern will persist through the long term thanks to initially-northwest flow that will be shifted only due to the slow development of a mean central United States trough that will keep below-normal temperatures in the cards. The 00 and 12 UTC global deterministic and ensemble guidance and related NBM output agree on the overall theme of the long term, with the primary highlights being 1) potential widespread frost on Friday night and Saturday morning, and 2) the increasing likelihood of widespread rain and embedded thunderstorms centered on the Sunday and Sunday night time frame. The NBM supported introduction of likely-level PoPs Sunday, and lingering shower chances through early next week. Highs through much of the period will be in the 50s F. && .AVIATION /Discussion for the 080000Z TAF Issuance/... Issued at 1038 PM EDT Tue Apr 7 2020 VFR conditions are forecast to prevail over the next few hours. The risk of thunderstorm development increases after 03 UTC as an approaching cold front will generate at least scattered thunderstorms with locally sub-VFR conditions possible in any storms. Timing of the potential storms is focused on the 03 to 10 UTC time frame, but confidence in impacts at any given terminal still remains too low for inclusion of more than a VCTS in any TAFs for now. At the moment, the north central and northeastern parts of the forecast area look to have the best chance for thunderstorms. Moving into Wednesday morning, confidence is increasing that MVFR ceilings in stratus will follow the cold front based on the latest model guidance and trends upstream. It isn`t out of the question that ceilings will dip into IFR categories with this stratus but the latest guidance has backed off a bit so will stick with MVFR for now. These ceilings should lift with a return to VFR conditions by about 15 UTC Wednesday. More clouds and even a few showers will approach KIND towards the very end of the period. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CJS NEAR TERM...ZH SHORT TERM...CJS LONG TERM....CJS AVIATION...ZH/CJS
Area Forecast Discussion
National Weather Service Marquette MI
625 PM EDT Tue Apr 7 2020 .SHORT TERM...(This evening through Wednesday) Issued at 404 PM EDT TUE APR 7 2020 As a warm front gradually lifts eastward across Upper Michigan this afternoon, visible satellite shows partial clearing over the western U.P. but most area remaining socked in with low clouds. Some fog has also developed due to high dew points advecting over what remains of the snowpack and rain falling onto it. Over the somewhat clear area, temps have risen into the low 50s but they remain in the low 40s over the cloudy areas. A few small, weak thundershowers will be moving east across Menominee County this afternoon as well but given the cool surface temps are obviously very elevated and are expected to stay well below severe limits given MUCAPE that`s only in the 100- 500 J/kg range per SPC Mesoanalysis. As that front continues to lift away, surface wind will become generally WNW and that clearing will expand to the central U.P. as well. Over the Keweenaw and east, however, fog that was generated today over Lake Superior will be advected onshore under this WNW flow and keep things socked in. Model visibilities get down to as low as 1/4 mile so it`s not impossible that a Dense Fog Advisory will be needed at some point tonight, but will hold off and wait until that actually forms before pulling the trigger. It should begin to diminish Wednesday morning due to both typical diurnal mixing as well as wind backing to WSW and thus less onshore. Tomorrow, a mid-level short wave will be pushing eastward through the Canadian Prairies and wrapping into a developing closed upper low. As this happens, a new low center is expected pinch off in northern Ontario and then deepen quickly tomorrow afternoon. The system`s developing cold front will push across the U.P. in the afternoon. This means temps will peak early afternoon (especially west) before cooling in the afternoon. Over the south-central, where skies will be clear more of the day and the front won`t arrive until after peak diurnal heating, highs should reach the mid to upper 50s with an isolated 60 reading not out of the question. NW winds will also become blustery in the afternoon behind the front with sustained winds up to 20 mph and gusts up to 30 mph expected. Despite strong fgen with the front, it remains to be seen if any showers will form with that forcing. The RAP is by far the most aggressive in developing a wave of rain and lifting it north along the front since it shows stronger low-level theta-e advection than in other models. The other CAMs have spottier showers which makes more sense, so have gone with just chance POPs south and east of a line from roughly Munising to Iron Mountain. Lapse rates will not support any thunder from these showers. .LONG TERM...(Wednesday night through Tuesday) Issued at 352 PM EDT TUE APR 7 2020 Below normal temperatures look to prevail with chances for showery precipitation through the end of the week as a slow moving cutoff low gradually tracks south-southeast across the Great Lakes region. Wednesday night into early Thursday morning, much colder air starts to drop south across the region under prevailing northwest flow. 850mb temperatures look to cooling to -8 to -10C, and the depth of this cold air advection and steeper lapse-rates aloft will allow for some deeper mixing. This should help support mostly all snow as a p- type, but kept snowfall amounts on the lower side given the stronger winds aloft should help shred dendrites quite a bit. Snow should hold on throughout the day on Thursday especially downwind of Lake Superior, but across the far south-central any showers that make it down that way should switch over to rain as temperatures warm just above freezing. During this time period, the deep mixing tapping into winds loft around 30-40 knots should allow for blustery conditions, with some concerns for lakeshore flooding mainly east of Marquette along the Lake Superior shoreline. By Friday, the colder air continues to stream across the area under northwest to north flow. However it does look like drier air and increasing subsidence starts to move into the region as surface high pressure arrives from the west. Therefore, did opt to leave the drier NBM PoPs in there for now. PoPs look to be a bit aggressive for the weekend, but opted to leave them as is for as there is some uncertainty. By early next week, a trough becomes well organized across the central CONUS with a system deepening as it lifts northeast across the region. Depending on the track of the system we find ourselves on the wrap around snowy side of the system and would be more impactful across parts of Upper Michigan. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 625 PM EDT TUE APR 7 2020 Confidence is low with these TAFs as low level moisture will try to clear out, but winds also get light overnight which could cause re- emergence of fog and stratus again. IWD will be VFR until later tonight when fog moves in and takes them down to IFR briefly. CMX will stay VLIFR overnight with upslope westerly wind off of Lake Superior before improving to VFR by Wed afternoon. SAW is trickier and thinking is they will lose the low stratus early, then fog develops and they will go MVFR overnight and then VFR by Wed afternoon. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 404 PM EDT TUE APR 7 2020 Main story tonight will be areas of fog, possibly dense, due to rain falling over the lake and moist air advecting over it. Models are all aggressive in showing widespread visibilities less than 1 mile so have issued a Dense Fog Advisory through late morning Wednesday. Winds during this period will remain light. Wednesday afternoon, a cold front will push across the lake with WNW winds increasing to 20- 30 kts behind it. Winds are expected to increase further Wednesday night with gales becoming widespread east of Isle Royale and the Keweenaw. These gales will last through the day Thursday before diminishing Thursday night, with some periods of high-end gales to 40 kts possible, especially early Thursday morning. Winds subside below 20 kts across the lake on Friday and are expected to stay light through the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Dense Fog Advisory until 11 AM EDT /10 AM CDT/ Wednesday for LSZ240>251-263>267. Gale Watch from late Wednesday night through late Thursday night for LSZ244-245-264-266-267. Gale Watch from late Wednesday night through Thursday evening for LSZ265. Gale Watch from late Wednesday night through late Thursday night for LSZ249>251. Lake Michigan... Dense Fog Advisory until 11 PM EDT this evening for LMZ221-248- 250. && $$ SHORT TERM...RJC LONG TERM...Ritzman AVIATION...07 MARINE...RJC
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 400 PM CDT Tue Apr 7 2020 The day started with dense fog across much of the area, but a powerful April sun and some dramatic BL mixing behind a wind shift have since left us with blue skies. It was clear early this morning that the same mixing would be driving dewpoints lower and temperatures higher than previous forecasts. HRRR and RAP seemed to have best handle on it and blended them into the forecast to drive numbers significantly higher. Sure enough, records began to fall already by noon. .Tonight: A RED FLAG WARNING was foisted over the western half of the CWA with wind gusts over 30 mph at times and RH values as low as 15 percent. Expect improved conditions with the setting sun this evening. It is set to expire at 7 pm. .Wednesday and Thursday: The cold front draped across the Dakotas will impact this area on Wednesday. Expect the front to sweep through during Wednesday`s mid- section, leaving a wide range of high temperatures in its wake. Mid- 50s up north will end up falling 20 degrees shy of the marks set along the Kansas state line. Highs in the south will be recorded before the front`s passage during the lunch hour. Chances of showers are minimal at best, but do have a slight chance along the SD border and in parts of western Iowa. Kept QPF at zippo. Winds will peak just as quick or quicker than Tuesday with gusts of 35 mph forecast in the afternoon. Fire danger will dip lower than today`s categories. Thursday will be cooler than average early April highs with numbers maxing in the 40s and 50s. As the surface high settles in Tuesday night, temps will slip sub-freezing across the CWA. .Friday and beyond: Upper low in south central Canada continues to dominate the forecast in the long range, keeping our flow under it`s oppressive thumb. Expect southwest flow to help drive temps quickly but only slightly warmer for Friday and Saturday. Numbers will fall shy of seasonal norms. A short wave will kick up a chance of showers and a few rumbles of thunder for Friday. Easter does not look conducive to egg hunts as a cold front will knock temps into the 40s with brisk NW winds and the week`s best chance of showers. Some of the showers may fall as snow if they coincide with the diurnal dip. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 636 PM CDT Tue Apr 7 2020 VFR conditions are expected to persist through the TAF period with a cold front moving through tomorrow that is not expected to produce precipitation. Strong mixing this afternoon took care of our surface moisture, therefore fog is not expected to be an issue tomorrow morning and should be limited well into western Iowa. Ahead of the cold front, wind speeds are expected to be very low overnight, and may vary direction at times. Winds behind the cold front will be gusty, with KOFK and KLNK being the most likely to reach 30 knots. Once the cold front passes, little change in wind speed is expected through the TAF period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Red Flag Warning until 7 PM CDT this evening for NEZ016-017- 030>032-042>044-050-051-065-066-078-088>090-092. IA...None. && $$ DISCUSSION...Nicolaisen AVIATION...Petersen
Area Forecast Discussion
National Weather Service Blacksburg VA
743 PM EDT Tue Apr 7 2020 .SYNOPSIS... A nearly stationary boundary was located from Western Pennsylvania to Eastern Virginia, while a cold front was noted across the northern Missouri Valley. This cold front will move into our region Wednesday ahead of a stronger cold front that will quickly push through our area Thursday. Showers and thunderstorms, some with locally gusty winds and hail will be possible Wednesday and Thursday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 245 PM EDT Tuesday... Showers and thunderstorms continue to develop along the northern edge of of an instability axis in a zone of warm air advection. Many of the short range and high-res models have performed very poorly, with the 16Z HRRR and 12Z NAMNest showing no precip in our area at 18Z. Considering CAPES are 500-1000 J/KG and effective bulk shear values are over 35-40 knots, expect additional thunderstorms to develop during the daytime hours with the potential for hail and locally damaging winds. This activity should diminish with loss of heating, but then our attention turns to an approaching cold front from the north with will generate a line (or MCS) of showers and storms that many of the high res models agree push into our forecast area before or around dawn Wednesday. Increased winds overnight, especially in the higher elevations as a low level jet strengthens. This also will keep temps on the warm side of guidance values, especially at BLF. On Wednesday, this boundary pushes south into our forecast area, and while there is uncertainty about the amount of clearing after morning showers/storms, we expect enough heating to again generate scattered showers and storms. HREF output showing CAPES in excess of 1000 J/KG where moisture (which is expected to be deeper compared to today) will be pooling, primarily south of Highway 460. Threat for large hail and damaging winds is possible, and may be higher than today. Stayed close to the previous forecast for highs on Wednesday, but confidence lower behind the boundary in BLF/LWB where spread in the guidance is large. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 210 PM EDT Tuesday... After the afternoon convection from Wednesday dies off and moves to our east, focus turns to a cold front that will arrive early Thursday morning. Confidence is high now that there will be some embedded convection with this line when it arrives thanks to CAPE values up to 500j/kg. Likewise, shear/helicity will increase ahead of the line, but guidance keeps a bulk of the greatest amounts to out north. It`ll be worth keeping an eye on in case anything isolated severe occurs. After the fronts passage Thursday, our warmer weather takes leave and allows cooler weather to return. Along with the cold air return, gusty NW flow sets in. The western half of the CWA is highlighted by 40-50kt 850 winds aloft that could very likely mix down Thursday night into Friday. Still not confident if we will need a headline out for the wind or not, but certainly watching to see if something will be needed. Obviously with stout NW flow, upslope should be expect. Confidence is increasing in some light snow showers overnight into Friday. Don`t get excited though. Most snow that falls will melt on contact with the round with such warm ground temps. Right now, only western Greenbrier should expect any accumulating snowfall (less than .5"). Upslope tappers off midday Friday as NW wind gradually diminishes. After that, we prep for a dry Friday night which should bring a big shock temperature wise given the recent warm weather. Waking up Saturday, much of the west will be waking up to below freezing temps, with parts of the east not far from it. That said, with the growing season started for the east, frost will be of concern. After the cold start Saturday, the remainder of the day looks high and dry with lots of sunshine to try and warm things up in the afternoon. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 200 PM EDT Tuesday... Guidance continues to get a better handle on the pressure system that is currently sitting off the California coast. Late in the week, this low gets kicked onshore and crosses across the southern U.S., eventually shifting northward to the Mid-Atlantic. Timing has come into much better agreement, with first a warm front lifting northward across the area early to mid day Sunday. With the warm front comes a return of warmer weather. By Sunday night, the cold front associated with this low will then cross the region. Total rainfall with this system looks pretty beefy compared to some of the rain events we`ve had recently. Right now, rain amounts could range between 1-2". After Sunday`s system exits, we cool off again for Monday, though not like what happens this Thursday/Friday. Guidance hints that NW flow will establish some upslope showers Monday into Tuesday. Precip type at the moment remains rain, but temperature profiles will need to be watched over the coming days as new guidance arrives. Any area that would have the potential for snowfall would again be most likely western Greenbrier, similar to this coming Friday AM. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 735 PM EDT Tuesday... Wind will stay mixed overnight and higher elevations may have gusts up to 30 knots as a low level jet strengthens. An approaching cold front from the north will bring showers and isolated thunderstorms to southern West Virginia and northern and central Virginia by early morning first impacting KLWB and KBLF before moving south. MVFR cigs will develop due to westerly upslope winds over the mountains at KLWB, KBLF and KBCB overnight, with the potential for IFR cigs. These MVFR cigs will continue through much of the morning on Wednesday. Occasional showers and isolated storms will also impact KBCB, KROA and KLYH on Wednesday, periodically reducing cigs and vsbys to MVFR levels. Models had showers and thunderstorms redeveloping along the front after 15Z/11AM. Any storms will reach KDAN later in the day. Above average confidence for the coverage and timing of showers and thunderstorms tonight and Wednesday. Average confidence for wind, ceilings, and visibility. Extended Aviation Discussion... A strong cold front crosses the area Thursday morning with widespread MVFR conditions due to clouds and precipitation. Winds will be strong and gusty behind the front Thursday night. Colder high pressure builds into the area on Friday. In general winds will be diminishing and ceilings will improve to VFR except some lingering MVFR in the mountains. Another system may bring rain our way later Saturday with sub- VFR ceilings, though at the moment confidence is low. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PH NEAR TERM...AMS/PH SHORT TERM...RR LONG TERM...RR AVIATION...AMS/PH