Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/16/18

Area Forecast Discussion
National Weather Service Columbia SC
1033 PM EDT Sun Apr 15 2018 .SYNOPSIS... Cold front continues moving toward the coast and will move offshore by the early morning hours. Overnight high pressure along with cooler and drier air will begin building into the region with dry weather expected Monday through Wednesday. A moisture limited cold front will cross the region Thursday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Precipitation is now just exiting the Pee Dee and eastern Midlands late this evening with a cold front pushing through the central Midlands. As front moves through the area late this evening, winds will pick up again as cold advection develops. Strong winds expected on area lakes overnight with 30 to 40 knots at 2000 ft and some mixing. Will continue lake wind advisory overnight into Monday. As drier air begins moving in expect some clouds to dissipate especially toward daybreak. Overnight lows will be in the mid 40s to around 50. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... A dry westerly flow associated with ridging along the Gulf Coast will dominate through Wednesday. The pressure gradient between this ridge and low pressure well to the north combined with mixing will result in breezy conditions during the days. The NAM and GFS Bufkit momentum transfer tool suggests gusts 20 to 25 knots. Followed a guidance consensus for the high temperature forecast. Leaned toward the higher low temperature guidance because of mixing. Lake wind advisory until 800 pm with gusty winds to near 30 mph in the afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The medium-range models indicate dry conditions with ridging mainly dominating through Saturday. Little moisture is depicted with a cold front Thursday. Moisture may increase Sunday in an onshore flow and ahead of a frontal system. The GFS and ECMWF ensemble mean supports pops less than 20 percent through Saturday and 20 to 30 percent Sunday. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Generally low confidence in cig restrictions due to proximity of upper trough. Cold front beginning to move into Midlands late this evening. The heaviest precipitation has moved east of the TAF sites. Still expecting wind speeds to remain a bit elevated into the overnight hours. Biggest challenge will be cigs. Both 12Z NAM and GFS BUFKIT time sections showing lots of low-level moisture across the area overnight into the afternoon hours on Monday. However, latest HRRR model indicating little in the way of any cigs overnight into the daytime hours Monday. Accordingly, cig forecast is somewhat on the low side. Strong winds with occasional gusts should hinder very low cigs, so MVFR cigs look most likely. If enough downsloping occurs, would expect cloud deck breaking up to some extent. However, mainly SW to W sfc winds overnight into Monday are not usually not conducive to good downsloping conditions. Anticipate cigs mostly at the MVFR level at all TAF sites until around 13Z Monday. May see more clouds at CAE/CUB/OGB after sunrise Monday than at AGS/DNL due to proximity of the upper trough swinging through the region. As a result, thinking VFR cigs at CAE/CUB/OGB for much of tomorrow, with scattered cloud decks at AGS/DNL, but confidence is not great. Winds will again remain strong and gusty for much of daytime hours on Monday. EXTENDED AVIATION OUTLOOK...Strong and gusty winds expected through Monday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...Lake Wind Advisory until 8 PM EDT Monday for GAZ040-063>065- 077. SC...Lake Wind Advisory until 8 PM EDT Monday for SCZ015-016-018- 020>022-025>031-035>038-041. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
958 PM CDT Sun Apr 15 2018 .DISCUSSION... The forecast is in good shape tonight with no major changes needed. Onshore flow will resume tonight, which will keep temps up a several degrees compared to last night. Temps look on track with lows in upper 40s over the Victoria Crossroads, 50s elsewhere inland, and low 60s along the immediate coast. Hourly wx grids were cleaned up to match latest trends. Updated products all ready sent. && .PREVIOUS DISCUSSION... /Issued 635 PM CDT Sun Apr 15 2018/ DISCUSSION... Updated for 00z aviation. AVIATION... VFR conditions will prevail for the next 24 hours at the South Texas terminals. Southeasterly winds will increase on Monday with gusts in excess of 20 knots during the afternoon. PREVIOUS DISCUSSION... /Issued 351 PM CDT Sun Apr 15 2018/ SHORT TERM (Tonight through Monday night)... Concur with the deterministic GFS/ECMWF/NAM that the upper pattern will be progressive with the upper disturbance over the Midwest/ Mississippi Valley moving EWD across the ERN CONUS while another upper system entering then moves across the WRN CONUS. The foregoing will favor a transition to onshore flow over the CWA/MSA by tonight/Monday. In response to onshore flow, the NAM deterministic predict near surface saturation/light sfc wind 09z-12z Monday over portions of the CNTRL/ERN CWA. Yet, not confident that fog will develop given very low SREF visibility probabilities. Not as cool tonight as near surface moisture modulates radiational cooling. PWAT values expected to remain well below normal during the period (NAM deterministic) and thus no precipitation expected. A gradual warming trend expected Monday/Monday night (GFS deterministic 1000-500mb thickness values.) MARINE (Tonight through Monday night)... Expect onshore flow to increase to moderate to strong levels Monday night as the surface low deepens over the Southern Plains. An SCA may be needed Monday night for the coastal waters. FIRE WEATHER (Tonight through Monday night)... Will not upgrade the Fire Weather Watch, currently in effect for LaSalle/Webb/Duval Monday, given lack of high confidence that wind speeds will reach the critical threshold. Deterministic HiRes NMM, NAM, and GFS predictions suggest with wind will barely approach Fire Weather Warning threshold. Will defer to later shifts given greater accuracy/skill of deterministic output for the 18z Monday- 00z Tuesday period and inclusion of RAP deterministic output for that period. LONG TERM (Tuesday through Sunday)... Long term period begins with continued quiet weather as upper level ridge remains in place over the region. Onshore flow will increase Tuesday with small craft advisory conditions likely continuing. Moisture will be a bit slower to come back than we have seen lately with mid 60s dewpoints not expected into the coastal counties until Tuesday evening. A cold front will approach the area Tuesday night into Wednesday associated with an upper level disturbance well to the north. This front should stall north of the area, only veering winds in South Texas to the east. The front will interrupt the steady onshore flow and bring lighter winds to the area mid-week. With only limited moisture return ahead of the front, do not expect any mentionable pops ahead of the boundary, but will eventually get a tap of moisture from the south into Thursday to begin rain chances. A deeper upper level trough moves into the central US late week and into the weekend bringing another boundary down. This one looks like it should have enough support to move through South Texas. Additionally, enough moisture should have pooled ahead of the front this time to bring higher end chance pops. Expect warming temps Tuesday and Wednesday with highs back into the 90s west, then more seasonal temperatures later in the week. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 57 80 64 84 68 / 0 0 0 0 10 Victoria 48 79 59 84 66 / 0 0 0 0 10 Laredo 57 88 63 93 67 / 0 0 0 0 0 Alice 53 84 60 89 66 / 0 0 0 0 10 Rockport 63 76 69 83 71 / 0 0 0 0 10 Cotulla 52 87 59 92 64 / 0 0 0 0 10 Kingsville 55 83 62 88 68 / 0 0 0 0 10 Navy Corpus 65 78 69 83 71 / 0 0 0 0 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...Fire Weather Watch from Monday afternoon through Monday evening For the following zones: Duval...La Salle...Webb. GM...None. && $$ TB/78...SHORT TERM
Area Forecast Discussion
National Weather Service State College PA
1032 PM EDT Sun Apr 15 2018 .SYNOPSIS... A strong storm system will sweep through the region tonight and early Monday. Much cooler weather will follow through the middle of next week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... MRMS RALA shows shield of moderate rain has overspread the western half of the forecast area at 02Z, while just spotty light rain/drizzle noted over eastern Pa. Maddox synoptic type heavy rain event shaping up tonight, as negative tilt upper trough pivots east, preceded by a strong southerly low level jet with v-wind anomalies in the 3-4SD range and associated plume of anomalous PWATS with origins over the Gulf of Mexico. GEFS MClimate data showing 12hr qpf exceeding model climatology over a good portion of southern Pa. A blend of latest model data supports a widespread 1-2 inch rainfall. However, latest HRRR runs and earlier convection- allowing HREFV2 support the potential of localized amounts in excess of 3 inches. The heaviest rain will likely fall late tonight and early Monday morning in association with embedded elevated convection/tsra. Have included the chance of thunder over roughly the southeast half of the forecast area based on model CAPEs. Based on collaboration with LWX, have held off on a flood watch. Current thinking is that any flooding will be isolated in nature due to relatively dry antecedent conditions. However, will monitor closely for possible need to issue. The back edge of the steady rain should be coming into the southwest portion of the forecast area by dawn, as cold(occluded) front moves through. Based on current mesonet observations, believe a bit of fzra is possible over the highest terrain of northeast Schuylkill County late this evening. However, given the isolated nature of the threat and road temps well above freezing, do not anticipate any headlines. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Latest models indicate the extreme southeast part of the forecast area (Lancaster Co) may break into the warm sector between 12Z-15Z Monday morning, introducing the threat of severe wx. Strong winds aloft and marginal sfc-based CAPE noted in the models, hence the marginal risk of severe wx in this area from SPC. For most of the area, Monday will see us transitioning into a gusty and colder NW flow behind the departing surface wave and cold front. Steady rain will exit the eastern counties early, but lingering rain showers are expected in association with passage of upper trough. Over the Alleghenies, the rain showers will likely mix with snow showers toward evening. However, temps too warm to support any accums. Highs in the 40s over most of the area will be some 10-15 deg colder than normal. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... On the back side of the strong front crossing the state Sunday night and early Monday, we will see yet another return to colder than normal weather and even a couple of opportunities for snow showers. The first chance for snow showers will be Monday night and early Tuesday as the upper low swings through to our north. Another system may bring more snow showers Wednesday night into Thursday. We don`t expect any significant accumulations, but as we enter mid April, the prospects for snow are less than welcome. Past Thursday we foresee a break of dry weather into early next weekend as energy reloads over the southwestern U.S. allowing weak upper ridging to build over the eastern part of the country. Yet another upper low in this busy pattern looks to drop into the deep south toward the end of the period...possibly spreading some precipitation toward our region for the beginning of next week. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Gusty winds and LLWS will be the main problems overnight, as a tight pressure gradient is present between a cold high pressure system to the northeast and low pressure to the west and south. Very strong frontal inversion remains in place. Some bands of rain to the west, will continue to move eastward overnight. Small band of thunderstorms over central VA, but very cold air at the lowest 5000 feet, hard to see much thunder in our area, so left out of the 00Z TAFS. Conditions should improve later on Monday, as the cold front moves east of the area. Outlook... Mon...Rain will taper to showers W to E. MVFR/IFR early trending VFR PM central/eastern 2/3. Rain/snow showers and sub-VFR cigs continue western 1/3 into Mon night. Tue...MVFR ceilings western 1/3 with lingering rain/snow showers. VFR elsewhere. Wed-Fri...Chance of rain/snow showers with sub VFR most likely NW 1/2. && .HYDROLOGY... 1 to 2 inches of rain is expected Sunday night into Monday morning and will result in significant rises on area rivers and streams. Latest guidance has trended a bit lower on total rain/QPF and shifted the axis of heaviest rain slightly eastward toward the Lower Mainstem Susq basin, where FFG values are the highest. High res models still show the potential for localized max amounts of 3+ inches which would cause some runoff problems. Small streams will see the greatest runoff-response with rapid/sharp rises expected. Small streams will be the most susceptible to flooding. Several river points are forecast to reach action/caution stage and minor flooding is possible. There is also the potential for localized short duration ponding/flooding especially in urban corridors and poor drainage areas. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald/La Corte NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald/La Corte LONG TERM...La Corte/Gartner AVIATION...Martin HYDROLOGY...
Area Forecast Discussion
National Weather Service Dodge City KS
641 PM CDT Sun Apr 15 2018 ...Updated Aviation Section... .SHORT TERM...(This evening through Monday) Issued at 351 PM CDT Sun Apr 15 2018 High surface pressure will settle over central KS overnight allowing light and variable winds to develop by early Monday morning. This very dry airmass should radiate strongly with the subsident region of the upper ridge aloft, and dew point depressions down around 1 degree or less by 12 z in central Kansas. Light to moderate southeasterly winds will be found over most of the area through the day Monday marking two thermodynamically separate airmasses. Recirculated cool air over the central Kansas counties will limit to around 60 degrees while extreme southwest KS will likely reach the low/mid 80s. .LONG TERM...(Monday night through Sunday) Issued at 351 PM CDT Sun Apr 15 2018 Strong shortwave moves through the area Tuesday night with potential for a few hours of near high wind criteria northwesterly surface winds behind the cold front. Mixing may be somewhat limited as the timing looks to be more in the overnight hours than the well mixed higher lapse rate daytime. Prior to the fast moving front, temperatures will warm homogeneously into the 80s across the forecast area, possibly pushing 90 degrees near Oklahoma. By Friday through Saturday, potential increasing for a precipitation event that may significant rain of an inch or more for parts of the areas (central Kansas), with slightly less farther west. The GFS and ECMWF have generally been showing such solutions for a couple of days now. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 639 PM CDT Sun Apr 15 2018 North winds at TAF issuance time in the 12 to 14 knot range will quickly diminish and become light and variable as a high pressure ridge axis expands across Kansas tonight. This ridge axis will push east early Monday, and as another leeside trough develops across eastern Colorado, winds will pick back up out of the south late in the morning, especially GCK and LBL terminals. && .FIRE WEATHER... Issued at 328 AM CDT Sat Apr 15 2018 Current trends support the HRRR surface elements RH and wind gusts forecast for red flag conditions across a portion of the area. A large portion of the area between U.S. Highways 83 and 183 should see frequent gust to 30 mph with relative humidity already at 15 percent and likely to drop a couple of more percent. A Red Flag Warning has been posted until 7 pm for these areas. Red Flag Warnings have been posted for the extreme southwest counties on Monday, and most of the area behind the warm front on Tuesday. && .PRELIMINARY POINT TEMPS/POPS... DDC 26 68 42 84 / 0 0 0 0 GCK 27 71 40 83 / 0 0 0 0 EHA 35 83 48 83 / 0 0 0 0 LBL 32 80 44 86 / 0 0 0 0 HYS 21 60 37 78 / 0 0 0 0 P28 26 64 45 86 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 7 PM CDT this evening for KSZ044-045-063- 064-077>080-087>090. Red Flag Warning from noon CDT /11 AM MDT/ to 9 PM CDT /8 PM MDT/ Tuesday for KSZ043>046-061>066-074>081-084>090. Red Flag Warning from noon CDT /11 AM MDT/ to 8 PM CDT /7 PM MDT/ Monday for KSZ061-062-074>076-084>086. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Umscheid
Area Forecast Discussion
National Weather Service Duluth MN
919 PM CDT Sun Apr 15 2018 .UPDATE... Issued at 919 PM CDT Sun Apr 15 2018 Snow, heavy at times, continued over much of the Northland. The heaviest snow was located in a north to south band across central/western Saint Louis County south into Pine County with more heavy snow over Lake Superior into the Twin Ports region. We extended the Advisories and Warnings for most of our southern areas through midnight and upgraded the Winter Weather Advisory in the Arrowhead to a Winter Storm Warning. We still expect the snow to diminish in intensity for most areas overnight, it just may take longer. The snow should diminish first in southern areas, slowly working its way north late tonight into Monday morning. Additional snowfall accumulation is possible on Monday in the Arrowhead and along the South Shore. The wind was slowly subsiding and that trend will continue but it will remain windy along the South Shore. && .SHORT TERM...(This evening through Monday) Issued at 309 PM CDT Sun Apr 15 2018 Snow and blizzard conditions continue today with dangerous to near impossible travel conditions across northwest Wisconsin and parts of northeast Minnesota, including the Twin Ports. While no time is great for a blizzard, the timing of this storm on a Sunday and mainly wrapping up tonight should mean few people will venture out on to the roads and road crews should be able to get the upper hand against the weather in time for the Monday morning commute. Some snowfall will linger into the day Monday but overall new snow accumulation will be limited - the main focus is today/tonight. On the synoptic scale the upper low associated with this spring storm is centered over southern Iowa per RAP and 12z upper air sounding analysis. Over the next 24 hours the upper level longwave trough axis becomes negatively tilted with a 120-150 knot southerly jet ahead of it, resulting in height falls over the lower Great Lakes region. The surface low currently over the Ohio RIver Valley will track north, with the deep moisture that has advected across the Tennessee and Ohio valleys today being transported around the low to the Upper Great Lakes region, supporting a continued supply of deep moisture. This afternoon water vapor channel imagery from GOES- 16 vividly depicts this moisture transport process - while there has been a brief break in the precipitation over parts of northern Wisconsin today, the moisture transport continues to help saturate low and mid levels of the atmosphere. This will come together as the broad-scale lift intensifies today and tonight due to both the mid- level PVA as the mid-level closed low tracks eastward and weak warm air advection at low levels. In addition to the broad-scale pattern, lake-enhanced bands of snow are anticipated due to very favorable low level winds producing a long fetch over Lake Superior. While temps aloft are somewhat marginal (barely meeting the -12C to -19C ideal difference between air and water temp) and there is some concern about the speed of the low level winds producing too much turbulence to support long-last bands, the plentiful low level moisture, broad scale lift already in place, and very little directional shear is good enough to produce locally higher snowfall amounts. At this point wind directions look to favor more of a western Douglas county to eastern Carlton county band, but this should shift west or east, or we could even see a few different bands develop late today/tonight as winds shift to become more north-northeasterly. Along the north shore today there may also be a bit of terrain-driven enhancement along the ridge of higher elevations. .LONG TERM...(Monday night through Sunday) Issued at 309 PM CDT Sun Apr 15 2018 The strong storm system will continue to move slowly east of the region on Monday night and Tuesday. Some lingering snow showers will be found across eastern portions of the region Monday night, and along the south shore on Tuesday. A couple inches of snow will be possible across the Gogebic Range of mainly Iron county. Otherwise, Tuesday is shaping up to be a fairly quiet day with some sunshine across most of the area. The long range models continue to show a low pressure system moving across the Central Plains on Wednesday and Wednesday night, but only indicate a small chance of precipitation across our area. After Wednesday night, strong upper level ridging will move into the mid section of the country. This ridge will bring dry weather for the period from Thursday into Sunday. Temperatures will warm from the upper 30s to lower 40s on Tuesday, to the 50s on Friday, Saturday and Sunday. Overnight lows will generally be in the 20s throughout the period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 636 PM CDT Sun Apr 15 2018 Snow continued to affect much of the Northland early this evening and it was heavy in spots. The snow will gradually taper off from southwest to northeast overnight lasting into Monday over the Arrowhead and portions of the South Shore. The visibility will drop to a quarter to half mile in the heavier snow bands. Mainly IFR and MVFR conditions will occur through the period with some improvement Monday afternoon. As the low pulls further east, the wind will back to north tonight continuing on Monday. The strongest winds around Lake Superior will slowly subside overnight into Monday morning. && .PRELIMINARY POINT TEMPS/POPS... DLH 21 35 20 39 / 100 20 10 0 INL 19 38 20 43 / 80 30 0 0 BRD 20 40 20 43 / 90 10 0 0 HYR 23 33 20 40 / 100 40 20 0 ASX 22 33 23 38 / 100 70 40 20 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Winter Storm Warning until 7 AM CDT Monday for WIZ004. Winter Storm Warning until midnight CDT tonight for WIZ006>008. Winter Storm Warning until 10 PM CDT this evening for WIZ009. Blizzard Warning until 7 AM CDT Monday for WIZ001>003. MN...Winter Storm Warning until 7 AM CDT Monday for MNZ012-020-021- 037. Winter Storm Warning until midnight CDT tonight for MNZ038. Winter Weather Advisory until 7 AM CDT Monday for MNZ011-019. Winter Weather Advisory until midnight CDT tonight for MNZ034>036. LS...Gale Warning until 4 AM CDT Monday for LSZ121-140>148. && $$ UPDATE...Melde SHORT TERM...JJM LONG TERM...DAP AVIATION...Melde
Area Forecast Discussion
National Weather Service Hastings NE
648 PM CDT Sun Apr 15 2018 .SHORT TERM...(This evening through Monday) Issued at 254 PM CDT Sun Apr 15 2018 The center of the upper low is slow to depart, hugging the IA/MO border as it very slowly treks east. The pesky status shield will probably be a problem with forecast lows tonight. It is very slow to slip east, and has actually shown signs of retrograding west this afternoon. Tough call on sky cover in our east especially. HRRR keeps most of any fog just west of the CWA, but close enough for me to keep the patchy fog from the previous forecast in. Kept low temps similar, except raised a bit in our east where we may stay in the clouds. Lowered highs for Monday, judging by model performance for today. .LONG TERM...(Monday night through Sunday) Issued at 254 PM CDT Sun Apr 15 2018 A day of short-wave ridging will give us near normal highs for Tuesday before the next wave comes by Tuesday night. Most models continue to focus most energy north of us, but qpf amounts are showing up farther south. Could be cold enough for some snow, but not going to get too excited yet, as models were a bit overblown with the previous late season system. Stuck some thunder in for the evening with modest elevated CAPE still expected. Next focus will be weekend system. For the most part, it will be warm enough for mainly rain, although the ECMWF indicates a bit more colder air. Still a bit early to make any sweeping speculations on snow amounts for a latter half of April system, as far as snow is concerned. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 643 PM CDT Sun Apr 15 2018 The wind will quickly die down around and just after sunset and will even be light and variable through much of the day on Monday. Low clouds have been slow to push east out of Grand Island, but should eventually begin to break up later this evening. && .CLIMATE... Issued at 457 AM CDT Sun Apr 15 2018 As we continue our incredibly cold (overall) first half of April, various cold temperature records have been broken/could yet be broken for the April 14th-16th time frame at Grand Island and Hastings airports, our two primary climate records sites. The details follow: ALREADY OCCURRED: ** Coldest HIGH temp for April 14th, and also the coldest high on record so late into the spring! ** - Grand Island: New April 14th record of 31 degrees (previous was 35 in 1986). This was the latest spring occurrence of a max temp of 31-or-colder on record, the previous mark was 27 degrees on April 11, 1997. - Hastings: New April 14th record of 30 degrees (previous was 40 in 1993). This was the latest spring occurrence of max temp 30 -or-colder, the previous mark was 27 degrees on April 11, 1997 UPCOMING : ** Coldest low temperature for April 15th (this morning) ** - Grand Island: Record is 15 in 1905...forecast is 21 - Hastings: Record is 23 in 2014...forecast is 21 ** Coldest high temperature for April 15th (this afternoon) ** - Grand Island: Record is 32 in 2000...forecast is 33 - Hastings: Record is 32 in 2000...forecast is 33 ** Coldest low temperature for April 16th (Monday morning) ** - Grand Island: Record is 20 in 1904...forecast is 18 - Hastings: Record is 20 in 1951...forecast is 17 && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Wesely CLIMATE...Pfannkuch
Area Forecast Discussion
National Weather Service Marquette MI
811 PM EDT Sun Apr 15 2018 .SHORT TERM...(This evening through Monday) Issued at 428 PM EDT SUN APR 15 2018 ...Widespread winter storm continues and may linger through Mon in some areas... with secondary surge of moderate snow and blowing snow on Monday we have extended the warnings for central and eastern forecast area through Monday. Snow will not be as heavy on Monday compared to what is occurring at this time, but due to moderate snow and blowing snow the warning was extended. Upper low spinning well to the southwest over IA and northern Ill. sfc low of 1002 mb is well to the south over northern IN. Surge of deep moisture streaming north into Upper Michigan has supported prolonged period of S+ all day long over much of Upper Michigan. Snow totals thus far are 6-9 inches with totals over 10 inches in Menominee county as they had an earlier start. Due to sharp warm nose aloft seen on 12z APX sounding this morning, some mixed precip has been observed with a bit of rain mixed in earlier at ISQ and sleet into far eastern Upper Michigan. Per radar and HRRR trends, expect last surge of S+ (1-2"/hr snow rates) to affect most of Upper Michigan through 00z this evening. Expect some locations to end up with over a foot of snow just since daybreak this morning. Shortly after 00z/8 pm ET, snow intensity should diminish sharply to around 1/2" per hour or even less. Most of snow after 00z this evening through daybreak Monday will occur over higher terrain of western and north central Upper Michigan with upslope flow (may see additional snow accums of 2-4 inches). Dry slot moving up into cntrl Lk Michigan (see back edge of wideapread radar echoes) will result in loss of ice aloft by mid evening and we probably, given enough low-level saturation, are going to see snow transition to freezing rain or freezing drizzle mainly east of MQT to IMT. Could be light glaze of ice occur. Will keep ending time of warnings for Iron through Menominee county at 06z as most precip will be done by that time. Focus late tonight into Mon morning turns northern lower Michigan and eastern Upper Michigan as all the models are starting to come on board with idea of secondary upper low developing which allows sfc low to persist and try to back more into eastern Upper Michigan. Net result of this stronger forcing is support for an area of moderate snow to re-develop near Lk Superior and east (as enough deeper moisture moves back in to eliminate any freezing precip from tonight). NAM/GEM/GFS and latest EC all show the secondary upper low developing and associated deformation across much of north and east Upper Michigan. This forcing and moisture will be supplemented by sfc-H8 N winds with H85 temps -13c. So, good enough for upslope lift and also lake enhancement. Overall widespread additional snow on Monday will be 2 to 5 inches, with higher amounts over ncntrl Upper Michigan. Since the sfc low will be farther west, pressure gradient remains tight and winds/blowing snow will be more of a factor. Long story short, due to these trends, extended warnings for north central and eastern forecast area. Also did extension for Delta and Schoolcraft though those may be more marginal. Not confident enough that far west will get back into the better forcing/moisture for significant lake enhancement so left those warnings to expire at 12z Mon. Evening or mid shift can investigate further and make additional headline decisions over the western forecast area. It appears this late season storm just doesn`t want to let go! .LONG TERM...(Monday night through Sunday) Issued at 254 PM EDT SUN APR 15 2018 NAM shows a closed 500 mb low over the lower Great Lakes 00z Tue with a trough in the western U.S. The closed low moves into New England while the trough in the western U.S. moves into the central plains 12z Wed and into the corn belt by 00z Thu. Nam slowly diminishes the deep moisture and moves out the 850-500 mb q-vector convergence Mon night with the moisture moving out on Tue afternoon. GFS and ECMWF show about the same thing as well. System slowly departs with some lake effect pcpn continuing behind it. System on Wed looks to stay mainly to the south of the area. In the extended, GFS and ECMWF show a 500 mb trough over the eastern U.S. and another over the western U.S. 12z Thu with a ridge over the plains. The western U.S. trough moves into the southern Rockies 12z Fri with the eastern trough in New England. The southern Rockies trough moves into the central plains 12z Sat. Differences show up on Sun between the GFS and ECMWF with the GFS moving the trough into the lower Mississippi River valley and the ECMWF shows a trough in the southern plains 12z Sun which is slower than the GFS is. Temperatures look to stay below normal for this forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 809 PM EDT SUN APR 15 2018 Improvement in conditions is expected this evening as the area of heaviest snow departs and winds gradually diminish. Still, IFR conditions are likely to prevail at all terminals through most of Monday. With snowfall increasing again Monday morning, ocnl LIFR vsby may be possible. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 254 PM EDT SUN APR 15 2018 Tight pressure gradient between strong high pressure to the ne and low pressure in the lower Great Lakes will continue the east to northeast gales of 35-45kt tonight across Lake Superior along with freezing spray. Winds will diminish below gale force Mon afternoon. Winds for the rest of the week will be under 25kt. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning until 8 AM EDT /7 AM CDT/ Monday for MIZ001>003-009-084. Winter Storm Warning until 8 PM EDT Monday for MIZ004>007-013- 014-085. Lakeshore Flood Advisory until midnight EDT /11 PM CDT/ tonight for MIZ001>006-009. Winter Storm Warning until 1 AM CDT Monday for MIZ010>012. Lake Superior... Gale Warning until 6 PM EDT Monday for LSZ243>251-264>267. Gale Warning until 1 PM EDT /noon CDT/ Monday for LSZ162-240>242- 263. Lake Michigan... Gale Warning until 2 AM EDT Monday for LMZ221-248-250. && $$ SHORT TERM...JLA LONG TERM...07 AVIATION...JLB MARINE...07
Area Forecast Discussion
National Weather Service San Francisco Bay Area
852 PM PDT Sun Apr 15 2018 .SYNOPSIS...A cold front will continue to spread rain through the southern portion of our area this evening. Scattered showers are forecast behind the front overnight. More widespread shower activity is likely on Monday, along with a slight chance of thunderstorms. Dry and cool conditions are forecast for Tuesday and most of Wednesday. A fast-moving system is then forecast to bring light amounts of rain from late Wednesday into early Thursday. Dry weather and warmer temperatures are likely by late in the week. && .DISCUSSION...As of 8:50 PM PDT Sunday...A cold front that began moving into the North Bay early this afternoon had moved through most of the SF Bay Area by early this evening. Currently, radar and satellite show the front across the South Bay and moving through the Monterey Bay Area. Rainfall totals with the front have been light, mostly less than a half inch. The most rainfall thus far is 0.66" at Mount Tamalpais in Marin County. The 00Z NAM and latest HRRR both indicate scattered showers will continue behind the front overnight. Increasing shower activity is then expected on Monday morning as the cold core of an unseasonably cold upper trough approaches from the northwest. Lapse rates will steepen by Monday morning as 500 mb temperatures drop as low as -33 deg C over the Bay Area. There is a potential for thunderstorms across our entire forecast area on Monday, with the best chance across the North and East Bay where the NAM forecasts surface-based CAPE values as high as 550 J/kg during the afternoon. Showers and isolated thunderstorms on Monday could produce brief heavy downpours, small hail, and locally gusty winds. Models agree that shower activity will begin to taper off by late afternoon and end during the early evening hours. Additional rainfall totals through Monday are expected to be about a quarter of on inch, with locally up to a half inch or more where heavier downpours occur. Snow levels are forecast to drop as low as 3000 feet by Monday morning (and possibly a bit lower in the North Bay). A dusting of snow is possible on Bay Area peaks, and the highest peak in the Bay Area (Mount Hamilton) may pick up a couple of inches of snow by late Monday. Farther south in the Santa Lucia Mountains of Monterey County, as much as 3 or even 4 inches of snow is possible above 4000 feet. Dry and cool weather is forecast for Tuesday and most of Wednesday. A fast-moving system is then forecast to move in from the northwest and bring a quick shot of precipitation to our region from late Wednesday afternoon through early Thursday. Because that system will be moving through quickly, rainfall totals are expected to be less than a quarter of an inch. Dry and warmer weather is forecast late in the week and into next weekend. && .AVIATION...As of 5:00 PM PDT Sunday...A frontal system is moving through the SFO Bay Area accompanied by rain with MVFR cigs and breezy south to southwest winds. This front will spread into the South Bay after 01Z and the MRY Bay Area after 02Z. A wind shift to the southwest is expected after the front passes with rain ending. A few showers will develop tonight in the moist unstable airmass behind the front. Instability will increase on Monday with the daytime heating and shower activity should pick up in the afternoon. Vicinity of KSFO...MVFR cigs improving to VFR after 02Z after the front passes. Southerly winds gusting to 25 kt switching to southwest by 01Z. A few showers may develop tonight. Showers increasing after 18Z Monday. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...A few low clouds around MRY will keep occasional MVFR cigs until the front passes around 05Z. MVFR cigs during frontal passage at SNS between 02 and 05Z. Conditions improve to VFR after 06Z. && of 04:33 PM PDT Sunday...A cold front approaching the California coast will increase westerly winds over the bays this afternoon and evening. Northwesterly winds will become gusty over the coastal waters including the bays this tonight and Monday. There is a slight chance for thunderstorms near shore and in the bays Monday. Another system will arrive late Wednesday increasing winds. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm from 3 AM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 3 AM SCA...SF Bay until 11 PM && $$ PUBLIC FORECAST: Dykema AVIATION: W Pi MARINE: Sims Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Sacramento CA
215 PM PDT Sun Apr 15 2018 .SYNOPSIS... Pacific storm moves through today and Monday with rain, mountain snow, thunderstorms, and gusty wind. Dry Tuesday, then wet weather Wednesday into Thursday, with dry weather returning Friday. && .DISCUSSION (Today through Wednesday)... Pacific frontal system is spreading precip into western and northern portions of the CWA attm. Breezy to windy conditions have developed across Interior NorCal ahead of the front. Wind advisory has been expanded to include all of the Sacramento Valley and Delta as winds are stronger farther south than guidance suggested. Peak wind speeds expected now through early evening in the Central Valley. Higher resolution NAM-3KM and HRRR showing precip continuing to spread inland through the afternoon into evening. Models showing some Neg LI`s and increased CAPE along the front in the northern third of the CWA so an isolated afternoon thunderstorm with the front is possible. Helicity values are favorable for rotating storms, however CAPE is somewhat limited today. Precip turns showery over much of the Central Valley this evening, while heavier precip spreads into the Western Plumas mountains and Sierra Nevada. Snow levels this evening will initially be around 4500 to 6500 feet, but lower overnight behind the front. Heavier precip decreases in the Western Plumas mountains after midnight and in the Sierra Monday morning. Snow levels Monday morning expected to be around 3000 feet. Large cold upper trough moves into NorCal Monday with cyclonic flow keeping showers...heavy at the forecast Monday. Large area of neg LI`s depicted across Interior NorCal with highest values north of a KUKI-KOVE-KSVE line. 5H temps lower to -34 Deg C over this area in the afternoon with steepening lapse rates. 0-1 KM and 0-6 KM Bufkit vertical wind shear profiles suggest potential for isolated rotating storms. Abundant small hail likely with stronger cells and possible isolated funnel clouds or weak tornadoes. Storm total QPF looks to be up to around 0.60 inches or less in the Central Valley, locally higher with stronger convective storms. Liquid totals in the foothills and mountains through Monday range generally from around 0.5 to 1.5. Snow totals of 6 to 12 inches, locally higher, expected in the mountains of Western Plumas and Northern Sierra Nevada above 5000 feet. Winter weather advisory in effect as mountain travel likely to be difficult with slick roads, reduced visibility, travel delays, and chain controls. Showers decrease Monday night with drier and warmer weather returning Tuesday as upper ridging moves into NorCal. Ridging shifts east into the Great Basin late Tuesday, as next Pacific storm spreads precip into the CWA by Wed afternoon/night. PCH && .EXTENDED DISCUSSION (Thursday THROUGH Sunday) Forecast models indicate an upper low moving quickly overhead with a few lingering Sierra showers on Thursday. The upper low will shift to the east as a ridge of high pressure builds in. As a result, dry and warmer conditions are anticipated Friday into next weekend. Daytime highs could be 5-10 degrees above seasonal normals, with Valley highs potentially reaching the upper 70s to low 80s. && .AVIATION... Precipitation will continue across the area with occasional MVFR conditions over the Central Valley and widespread IFR over the northern Sierra Nevada through Monday. South wind gusts 20-25 kts Central Valley through 03z Monday. Thunderstorms possible over the Central Valley through 03z Monday, and again Monday afternoon after 18z. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 7 PM PDT Monday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. Wind Advisory until 8 PM PDT this evening for Carquinez Strait and Delta-Central Sacramento Valley-Northern Sacramento Valley- Southern Sacramento Valley. && $$