Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/12/20

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
919 PM CST Sat Jan 11 2020 .UPDATE... Issued at 913 PM CST Sat Jan 11 2020 Area of very light snow continues to diminish across the central part of the CWA this evening, and expect any ongoing precipitation to come to an end by midnight or so. No changes made to winds or temperatures at this time. && .SHORT TERM...(This Evening through Sunday Night) Issued at 309 PM CST Sat Jan 11 2020 Decent looking shortwave moving across western SD this afternoon, with an area of snow associated with it. Models not really picking up on this feature very well until recent runs of HRRR and other hi- res models. There are signals to keep this area of snow moving eastward through the CWA into the evening hours, so have inserted/increased POPs accordingly. More uncertainty remains as to just how much snow remains with this system as it continues to push into the eastern Dakotas. May have to make further adjustments to POPs later this evening. Snow accums will be on the light side. Southeast winds will continue to be breezy/gusty across central SD into the evening, thus creating some near-surface blowing and drifting snow. Even a bit of a downslope feature expected tonight on the western slope of the Coteau with about 25 to 30 knots of southeast winds at 925mb. Will then be watching low pressure moving east across the plains Sunday afternoon and night. Our far eastern/southeastern CWA may catch the northern/western extent of snow with this system, so will have snow chances mainly along and east of I-29. Although, not too confident any snow will even make it into the CWA given recent model solutions. Will continue to monitor trends. Temperatures tonight are a bit tricky. Will initially be dealing with cloud cover as the vort max moves through the region. Winds look to stay up a bit overnight too, although not so much in the James valley. Not expecting temps to drop too much overnight, but any clearing towards morning may allow temps to drop below forecast lows. Warm air advection is nothing noteworthy overnight. .LONG TERM...(Monday through Saturday) Issued at 309 PM CST Sat Jan 11 2020 A progressive mid-level flow pattern looks likely across the CONUS through the majority of the period. Energy within that flow will also likely have an impact on the weather across the Central/Northern Plains. While no major storms are expected at this time, several weather systems are anticipated. Better chances of measurable snow are expected for Tuesday into Wednesday as a couple systems track just south of the forecast area. Another decent looking low is expected to bring light snow to the area for Friday into Saturday. Overall, temperatures will be below to well below normal through the forecast. The coldest morning may be Thursday, but some models have backed off quite a bit on the cold air intrusion over the last couple runs. Plus, the lows we are forecasting are on the cold end of most guidance. As that period gets closer may have to adjust temps up a bit if model trends continue. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 527 PM CST Sat Jan 11 2020 An area of light snow showers will track across the western and central part of the area this evening. Vsbys may briefly fall into the MVFR category with the snow. Otherwise, VFR conditions will prevail across the area tonight and through the day Sunday, with the exception being the potential for some MVFR cigs to develop over the far eastern part of the area late Sunday afternoon. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Parkin SHORT TERM...TMT LONG TERM...TDK AVIATION...Parkin
National Weather Service Albany NY
946 PM EST Sat Jan 11 2020 .SYNOPSIS... Unseasonably warm weather will be over the region today into tomorrow morning. Snowmelt combined with a steady rain may bring a chance of flooding to the southern Adirondacks and west central Mohawk Valley. A strong cold front will bring a chance of thunderstorms later tonight into Sunday morning. Colder air will move back into the area Sunday afternoon with blustery conditions and a few snow showers in the mountains. High pressure moving through Quebec will bring cold but fair weather on Monday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of 946 PM EST...Slow moving cold front extends northeast from western New York across the Finger Lakes, Tug Hill, and northern Adirondacks. Ahead of this boundary, it continue to be very mild, with temperatures mainly in the 50s and 60s, while temperatures quickly fall into the 30s and 40s on the north side of the boundary. Some showers are starting to spread across the northwestern Adirondacks, but the remainder of the area has been dry with a warm, southerly breeze in place. Winds have been gusting over 30 mph at times, and this warm breeze has been allowing for plenty of melting of the snowpack across the high terrain. Over the next few hours, the 3km HRRR suggests it should continue to be remain dry for the majority of the area, as our area stays within the warm sector and the front only slowly drifts south and east towards the northern part of the area. The front will likely be stalling out as a wave on the boundary moves northward from the Ohio Valley towards the eastern Great Lakes and the front becomes occluded. After midnight, the wave of low pressure will be lifting across th eastern Great Lakes and some rain will be overspreading western areas first, and then moves across most of the region between 06Z-12Z with a strong convergent band of showers with some embedded thunderstorms especially from the Mohawk Valley/Saratoga Region south, as the occluded boundary moves eastward. There is only weak instability, but the dynamics and moisture are impressive for a strongly forced line of linear convection or broken line. Some of the CAMS are showing this. The influx of moisture is impressive with PWATs in excess of an inch and 850 hPa moisture flux anomalies in the +5 to +6 STDEVs range (combination of the H850 winds and PWATs which are both very anomalous). The H850 +v-anomalies /southerlies/ increase to +3 to +4 STDEVs above normal. A burst of locally heavy rain is possible with the front late tonight or early tomorrow morning. The highest rainfall totals are expected with the southwest flow over the southern Adirondacks with 1 to 2 inches during this time frame. Temps will not fall too much with lows mainly in the mid/upper 50s, except 30s over the upper Hudson valley and some upper 40s far northern Hamilton and Herkimer Counties, as some low-level cold air starts to seep southward across the Champlain Valley. Winds will be gusty with showers/storms as the front passes through. There is some instability as high as 200-300 J/KG in some of the CAMs. Likely gusts in the 40-50 mph range, but warnings are not out of the question. The time of day with the passage of the front is not optimal but LLJ is forecast to be in the 75 to 80 kt range just ahead of the front. SPC has expanded the general thunder to cover most of our area. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... Sunday...The cold front moves east of the region with the showers and any embedded thunderstorms ending. Strong cold advection will occur in the late morning into the afternoon. Temps may spike close to record levels again (See the Climate section below). Highs will be in the 50s to lower 60s (except the southern Adirondacks where 40s are likely), then temperatures drop during afternoon in the cold advection. Rain showers are forecast to change to snow showers over the southern Adirondacks and southern Vermont late in the day. Gusty south to southwest winds will shift to west and northwest behind the cold front. We could see some gusts 45-50 mph so wind advisory was issued in collaboration with neighbors. Sunday night into Monday...The strong cold advection continues into Sunday night with temps falling below freezing everywhere with high pressure building in. Lows will be in the teens and 20s. The winds will also diminish. Partly to mostly sunny skies are expected on Monday with high pressure building in form Quebec. A weak disturbance in the west to southwest flow aloft will increase clouds but we kept the day dry. Temps will still run slightly above normal but with highs in the low 30s north to lower 40s south. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... An active weather pattern is expected during the long range period with storm systems impacting the region roughly every 2 days. Temperatures will continue to run above average through at least Thursday, but then look to fall at or below average Friday and into next weekend. The first system arrives later Tuesday into Wednesday. An upper- level shortwave will progress across the Great Lakes while additional moisture associated with a stationary boundary stretching from Texas to Virginia lifts northward into our area. Boundary layer temperatures should result in mainly rain across the region, though some of the higher elevations could be cold enough for snow to mix in. Precipitation in general looks to be light. After a short break on Wednesday, the next system arrives for Wednesday night and Thursday. The synoptic setup looks fairly similar to the previous storm with another upper-level shortwave tracking across the Great Lakes and Northeast and additional moisture lifting northward from the stationary front stretching across the Southern states. This shortwave looks to be a bit stronger than the previous one. Pending on thermal profiles, mixed rain/snow look likely across the region once again. In the wake of this system, gusty winds and lake-effect snow are on tap later Thursday into Friday. A west-northwesterly trajectory would likely set up snow bands down the Mohawk Valley (perhaps into the Capital Region) and Catskills. Upslope snow showers will also be possible across western New England. After another brief dry period on Friday, the final system arrives for Saturday. At this time, this system would be the strongest of the three and contain the most moisture. At this time, thermal profiles would support widespread snow to start; however, temperatures may warm enough for a changeover to a wintry mix and/or rain, especially across the Hudson Valley. With this storm several days out, changes with regards to its track and p-types are expected over the coming days. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Flying conditions are currently VFR for the valley sites and MVFR for KPSF. Southerly winds have been around 5 to 15 kts, with a few higher gusts at times (mainly at KALB/KPSF). 2 kft will continue to be southwest around 35-50 kts tonight, so some LLWS will continue in places where surface winds are light (mainly KGFL/KPOU). A few showers are starting to spread towards KGFL, otherwise, mainly dry weather is expected through at least midnight, with flying conditions continued to be generally VFR for the next few hours. For late tonight, bands of showers will spread west to east across the region. There could be some embedded heavier bursts of rain (and possibly a rumble of thunder as well) just ahead of the front for very late tonight. Within the showers, MVFR/IFR conditions are expected for a brief time at all sites. Southwest winds will continue to be around 10 to 15 kts, with some higher gusts. After sunrise, rain will be ending, and winds will increase. West-southwest winds will be around 20 kts on Sunday, with gusts up to 35 kts (especially at KALB/KPSF). Flying conditions will quickly go back to VFR, with just bkn cigs around 3500-5000 ft for the morning and skies becoming few-sct by afternoon for all sites. Winds will decrease by Sunday evening. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of SHRA. Tuesday Night: Moderate Operational Impact. Likely SHRA. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: Moderate Operational Impact. Chance of RA...SN. Thursday: Moderate Operational Impact. Breezy Chance of SHSN...RA...SN. && .HYDROLOGY... Flood Watch has been continued from 6 pm EST Saturday to 6 pm EST Sunday for the southern Adirondacks, and west central Mohawk Valley due to runoff from snow melt and rainfall. NERFC river forecasts keep river levels just below flood stage at this time, but some minor flooding is possible in these areas. A significant precipitation/snowmelt event is expected over the southern Adirondacks. At this time we are expecting 1-2 inches of rain across areas north and along of Route 8. Based on NYS Mesonet snow observations, there is an estimated 1 to 3 inches of water equivalent in the snow pack in the Adirondacks, so there will likely be contribution of snow melt to the runoff in addition to rainfall with dewpoints expected to rise into the upper 40s to lower 50s in the mountains today into tonight and continued gusty winds. We also continue to monitor southern VT for any hydro issues. If confidence increases for more rainfall combined with snowmelt there, then the Flood Watch may need to be expanded into the Upper Hudson Valley and southern VT. Colder air moves back into the region Sunday afternoon into early next week and mainly dry weather is expected early next week which will help decrease river flows. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .CLIMATE... For Jan 11th... Record High for Albany is 57 set in 1975 Record High Min for Albany is 38F set in 1933 The Period of Record is 1874 to 2019 Record High for Glens Falls today is 54 set in 1980 The Period of Record is 1893 to 2019 Record High for Poughkeepsie is 63 set in 1975 The Period of Record is 1931 to 2019 For Jan 12th... Record High for Albany is 63F set in 2018 && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Wind Advisory from 4 AM to 3 PM EST Sunday for CTZ001-013. NY...Wind Advisory from 4 AM to 3 PM EST Sunday for NYZ032-033- 038>043-047>054-058>061-063>066-082>084. Flood Watch through Sunday afternoon for NYZ032-033-038>040- 042-082. MA...Wind Advisory from 4 AM to 3 PM EST Sunday for MAZ001-025. VT...Wind Advisory from 4 AM to 3 PM EST Sunday for VTZ013>015. && $$ SYNOPSIS...SND NEAR TERM...SND/Frugis/Wasula SHORT TERM...SND/Wasula LONG TERM...Rathbun AVIATION...Frugis HYDROLOGY...SND/Wasula CLIMATE...WFO ALY
Area Forecast Discussion
National Weather Service Gaylord MI
1004 PM EST Sat Jan 11 2020 .UPDATE... Issued at 1004 PM EST Sat Jan 11 2020 Evening analysis reveals a nearly negatively tilted short-wave trough swinging through the Midwest...associated mid-level circulation center is swinging through southern Illinois into Indiana. Attending surface low is across western Ohio. Warm conveyor belt and associated precip has peeled off well east of the state at this point. But, comma-head H8-H7 deformation/f-gen axis bisects northern Lower Michigan and down into southern Wisconsin. Further aloft, upper jet axis extends from the Ohio Valley up through northern Michigan and on across Ontario. Strong ascent along the warm side of the f-gen concert with upper level jet divergence...has produced a decent uptick in snowfall particularly along and south of a line from Manistee up through north-central Lower Michigan and further across Presque Isle/Alpena counties. North and west of that line on the descending side, radar returns have been steadily filling in. But, a very pronounced dry layer around 850 MB is really keeping snowfall at bay particularly through the tip of the mitt into eastern Upper Michigan. Most obs are VFR and reporting little or no snow. Mid level trough axis and associated forcing will be sliding through and out of the region over the next 4 to 6 hours or so with precip completely ending before sunrise. It`s become clear that the heavier snowfall with this system tonight will fall across the SE half of the forecast area with the heaviest amounts bisecting northern Lower Michigan SW-NE pretty much as described above. Thus, I`ll be making some fairly substantial adjustments to forecast snow amounts...really cutting back amounts across the tip of the mitt and E.UP...and even the far western counties (Manistee to Leelanau). With that, I`m also trimming winter weather headlines out of those areas. Further east, warning snowfall amounts will not likely be realized either. But, with some heavier snow at times and gustier winds/blowing snow, and the fact that it really just snowing pretty good in spots, it doesn`t make much sense to kill the warning at this juncture. I`ll let it ride for now. && .NEAR TERM...(Through Sunday) Issued at 225 PM EST Sat Jan 11 2020 ...Snow on the way tonight... 1003mb low pressure is a bit se of FWA. A warm front extends up the spine of Lakes Erie and Ontario, while a cold front trails off across the lower TN Valley. The warm sector is seeing temps in the 70s. 1033mb high pressure was in far northern Ontario, with single digit or colder afternoon temps in northern Ontario, most of MN, and points west. Wintry precip continues to the se of GLR; this is now mostly snow, though a mix with light freezing rain/drizzle was recently reported from Gladwin. The comma head of the presently neutrally-tilted system is over MO. The 500mb low opens up but takes on a negative tilt as it accelerates ne-ward tonight. We are seeing precip slowly become more expansive between the comma head and the frontal precip band in the southern lakes. This process should accelerate, with dynamics/lift intensifying rapidly to the ne of the ejecting upper low. Upstream precip is presently not impressive-looking; that is still expected to rapidly change. We are presently seeing some level of fgen response in the lingering precip over ne lower, with patches of 30dBz returns in an area (near Mio/Glennie) that should be all snow. That will continue to percolate there thru 6-7pm, before edging northward while intensifying. Fgen forcing will diminish somewhat as we become more thoroughly embedded in cold air. But trowal dynamics, and deformation with and ahead of the the comma head, will compensate. is inarguable that model QPF has trended lower for tonight as the day has gone on. 12Z ECMWF, 18Z Nam, recent Rap and HRRR runs are all a fair bit less wet tonight. I will be pushing the forecast a little bit in that direction, though without changing the going headlines (there`s enough blowing/drifting snow in the forecast to justify the current headlines). This will take 1-2" off of most snow amounts. Precip will gradually exit off to the ne Sunday morning, as high pressure tries to nose across Superior and upper MI. Ongoing northerly winds will rapidly diminish further as they veer easterly. Plenty cold enough for lake effect, but we will struggle to hold onto cyclonic curvature, and the incoming airmass is very dry and with a very shallow inversion (925mb). We`ll hold onto cloud cover near Lake Huron, but difficult to see how we can generate more than flurries once synoptic precip is gone. Partly sunny skies should return elsewhere. Min temps tonight single digits above zero in eastern upper MI, and upper single digits thru the teens in northern lower. Max temps Sunday mid teens to lower 20s. && .SHORT TERM AND LONG TERM...(Sunday night through Saturday) Issued at 225 PM EST Sat Jan 11 2020 High Impact Weather...None is expected at this time but there will be mainly light snow accumulations at times through the period. Forecast Concerns...Pops through the period and how cold it will turn later next week; chance for light freezing rain/drizzle across southeast zones Sunday night. The pattern after we get by our current storm system will feature an active northern jet stream with numerous short waves moving through the flow. This is expected to lead to periodic bouts of mainly light snow next week. There is a chance for a little light freezing rain/drizzle Sunday night across our southeast counties near Saginaw Bay. It could even be mild enough toward mid-week for a mix with rain in some areas. It will be fairly mild by mid-January standards to start off the week. Beyond that there is still a fairly sizable spread on the extent of possible colder air later next week (the GFS continues to insist that it will be much colder while the ECMWF and Canadian guidance is much less extreme). Our forecast will follow the blend which is more of a middle ground between solutions. This would allow for some lake effect snow on or about Thursday. Lastly, various extended models have been hinting that there may be a somewhat stronger system Friday night into the first half of next weekend but confidence of this occurring is on low side at this time (but definitely something to keep in mind as a possibility as we draw closer). && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1245 PM EST Sat Jan 11 2020 MVFR to VFR this afternoon. Conditions drastically worsening s to n tonight. Multiple waves of low pressure are advancing ne-ward along a front over the eastern Great Lakes and central Ohio Valley. Precipitation has waned for a period today, as cold/dry low level air briefly wins out. But heavier precip, this time in the form of snow, will advance northward again tonight. IFR to LIFR conditions expected at all TAF sites for part of tonight, especially late, in falling and blowing snow. Accums will be highest and conditions worst at APN, then TVC, then MBL/PLN. Snow- liquid ratios will be in the lower teens this evening, and the middle teens overnight. Conditions will improve considerably toward daybreak Monday. Ne to n winds will remain quite gusty through this evening and early overnight, then weaken somewhat. && .MARINE... Issued at 225 PM EST Sat Jan 11 2020 Ne to n gales will continue into tonight, between high pressure over far northern Ontario, and low pressure in the northern OH Valley. Winds will diminish somewhat overnight, but remain quite brisk into Sunday morning, as colder air enters the region. Light e to se winds expected late Sunday into Sunday night. && .MARINE... Issued at 225 PM EST Sat Jan 11 2020 Ne to n gales will continue into tonight, between high pressure over far northern Ontario, and low pressure in the northern OH Valley. Winds will diminish somewhat overnight, but remain quite brisk into Sunday morning, as colder air enters the region. Light e to se winds expected late Sunday into Sunday night. && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WARNING until 7 AM EST Sunday for MIZ021>023- 026>030-032>036-041-042. LAKESHORE FLOOD ADVISORY until 7 AM EST Sunday for MIZ020-026- 098. LAKESHORE FLOOD WARNING until 7 AM EST Sunday for MIZ018-024-030- 036-042-097. WINTER STORM WARNING until 8 AM EST Sunday for MIZ018-024. LH...GALE WARNING until 7 AM EST Sunday for LHZ345>349. LM...GALE WARNING until 7 AM EST Sunday for LMZ341. GALE WARNING until 4 AM EST Sunday for LMZ323-342-344>346. LS...GALE WARNING until 7 AM EST Sunday for LSZ322. SMALL CRAFT ADVISORY until 7 AM EST Sunday for LSZ321. && $$ UPDATE...BA NEAR TERM...JZ SHORT TERM...JZ LONG TERM...AS AVIATION...JZ MARINE...JZ
Area Forecast Discussion
National Weather Service Denver/Boulder CO
902 PM MST Sat Jan 11 2020 .UPDATE... Issued at 902 PM MST Sat Jan 11 2020 No need to make any changes to the current forecast. Light snow has been continuing over parts of the mountains with light accumulations. A band of light snow developed over the Denver area around 7 PM, but only produced trace amounts. That band has moved off further to the east. A weakly organized upper trough is moving into northwest Colorado at the present time which could help enhance snowfall in the mountains overnight. The Winter Weather Advisory for the north-central mountains will remain in effect. On the plains, the strong westerly component of the flow aloft will produce enough downsloping to keep conditions dry overnight. The latest runs of the HRRR show the light precipitation on the plains diminishing over the next couple hours and also show snowfall from the approaching upper trough decreasing through the overnight hours as the trough is moving over the mountains. All of these features are covered by the going forecast. && .SHORT TERM...(This evening through Sunday) Issued at 138 PM MST Sat Jan 11 2020 The fleeting stable ridge axis has weakened as it continues to move eastward onto the central US plains ahead of the next storm system set for the high country tonight and Sunday. Latest mid and upper level QG fields matching up fairly well with latest water vapor and IR satellite features currently over the northern Great Basin and UT vicinity. Forecast cross sections have been holding fairly consistent with this disturbance as it brings in deeper moisture after 00Z tonight and holds this against the Continental Divide for an extended period of time. This isn`t the best organized system so will likely see periods of drier air and varying amounts of stability tonight through Sunday. Current snowfall amounts in the advisory look on track with highest amounts over the far northern ranges. Totals should range from 4-7 inches across the higher mountain ranges with around 9-12 inches still expected for the Park Range in the vicinity of Mt Zirkel, Tower and Rabbit Ears. Down across the lower elevations tonight, conditions are expected to remain mostly dry. However, the NAM12, GFS and Canadian are suggesting a small area of banded light snowfall across the plains focused mainly on the north side of the Palmer Ridge. At this time, inclined to introduce isolated PoPs and very light QPF for this as the latest medium range models suggest a slight deepening of the trough as it passes onto the plains. This will need to watched this evening to see if the short range models run further with this or terminate it all together. Otherwise, will expect light winds across the region with a few strong gusts along the foothills of Larimer country and along the CO/WY border. Heading into Sunday, the weak trough axis passes across the Front Range near 12Z with a changeover to mid-level QG descent and high surface Omega values behind it. Cross sections indicate rapid drying of the atmos east of the Continental divide Sunday with a general pattern of westerly winds across the lower elevations through the day. Westerly gusts of 25-35 mph will be likely along the higher terrain along and near the CO/WY border. In the high country, despite decreasing dynamics, periods of light snow will persist through the day, primarlity from orographic lift in the moderate strength westerly flow behind trough axis. After comparatively warmer overnight temperatures tonight, daytime temps for Sunday will warm back into the 40s across the lower elevations. .LONG TERM...(Sunday night through Saturday) Issued at 138 PM MST Sat Jan 11 2020 The upcoming week will be characterized by a fast moving zonal west to northwest flow across Colorado. The results will be periodic snow and gusty winds in the mountains, but mainly dry and seasonable temperatures across lower elevations. For the details; the first impulse in the flow will move across Northern Colorado late Sunday night and Monday with a period of snow during the day. Cross sections show decent orographic flow of 20- 30kt along with steepening lapse rates. Moisture depth not all that deep, mainly up to 580mb, so snow amounts more likely near an advisory type situation. Since we still have advisory out through Sunday, won`t tack on another one just yet. As the trof passes by late Monday with enhanced subsident flow, westerly winds will increase and bring a brief shot of strong to near high winds across the higher mountains and exposed foothills with speeds of 40-65 mph. Lower elevations will remain dry with downslope flow and seasonable temperatures on Monday. For Tuesday, continued moist westerly flow and another embedded wave into the mountains with more light snowfall expected along with gusty west winds at times. Little change across the plains but models hint at a quick shot of snow across the plains on Tuesday night with the trof passage. By Wednesday, there will be weak ridging aloft while the flow turns a bit more southwesterly. This will result in a drier airmass over the mountains with little or no snowfall for Wednesday through daytime on Thursday. A stronger wave will develop over the Great Basin on Thursday and Friday with a moistening southwest flow on Thursday night before the open wave trof moves across Colorado on Friday. This will bring more snow in the mountains and even a chance of snow across the plains, though it looks more like strong winds than snow at this point. Drier conditions expected into next weekend as ridging aloft builds into Colorado. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 902 PM MST Sat Jan 11 2020 No aviation impacts are expected through the night and much of tomorrow. Winds will become southerly overnight and then trend to westerly tomorrow. The west winds may be gusty at times, with speeds up to 25 knots at KBJC and KDEN. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 11 PM MST Sunday for COZ031. && $$ UPDATE...Dankers SHORT TERM...Fredin LONG TERM...Entrekin AVIATION...Dankers
Area Forecast Discussion
National Weather Service Grand Rapids MI
954 PM EST Sat Jan 11 2020 LATEST UPDATE... Update .SYNOPSIS... Issued at 953 PM EST Sat Jan 11 2020 - Event will gradually wind down through 300am - Colder Sunday, light snow or freezing drizzle overnight - Milder Monday to Wednesday, then a couple chances for moderate rain or snow in the latter half of the week && .UPDATE... Issued at 953 PM EST Sat Jan 11 2020 Will continue the Winter Storm Warning into the overnight hours. It is in effect through 700am, but it will likely be able to be cancelled early (probably with the 400am forecast). The precipitation is expected to wind down from west to east across the forecast area between midnight and about 300am. At the present time the precipitation has flipped over to snow at almost all observation sites in our area, with the exception being Lansing where freezing rain is still being reported. Travel conditions are impacted per google traffic map from Holland, Wayland, Charlotte and Leslie northward. So, a sizeable portion of the area is experiencing impacted travel. In addition, google maps are showing two road closures on U.S. 127 north of Alma. Scattered power outages are noted across much of the area due to a fair amount of freezing rain (we have had some reports up to around a quarter of an inch). Heavier snow is occurring across West Central Lower Michigan up towards Ludington, Hart, Baldwin and Newaygo. This band of snow will work east across the area in the next few hours. Also, heavier precipitation associated with the upper wave located over Illinois an Indiana will move northeast though Southern Lower Michigan as well. Bottom line is the precipitation is not over yet with another burst of snow to work through most areas. The heaviest snow will likely be up in the northwest CWA (Ludington) and the far southeast CWA (Jackson) through 200am to 300am tonight. && .DISCUSSION...(This evening through next Saturday) Issued at 330 PM EST Sat Jan 11 2020 -- Several hours of heavier wintry mix or snow tonight -- Light wintry mix continues this afternoon, then we`ll get another several-hour burst of moderate to briefly heavy mix or snow late this evening into part of the overnight. This is associated with the deformation zone of the low, which is currently developing in Missouri. 12z mesoscale models advertised about 0.5 inches of QPF with this next round, though of note, the 18z NAM3 and HRRR are a little less aggressive with the heavier QPF shifted toward Jackson. Areas north of South Haven to Ionia to Alma have a chance of seeing a swath of 2 to 5 (isolated 6) inches of snow tonight, with Muskegon (and north) to Clare having the greatest chance. Snowfall rates could reach a half-inch to inch per hour for a couple hours late this evening. Temperatures falling deep into the 20s combined with gusty winds will make travel difficult if not hazardous during this burst of snow. In areas from Kalamazoo to Lansing and southeast, the burst of precip this evening into tonight will be predominantly sleet with some freezing rain, changing over to snow around midnight before ending prior to daybreak. -- Colder Sunday, light snow or freezing drizzle overnight -- Temperatures stay below freezing on Sunday, and in fact will stay in the teens for most of the day in Central Michigan. Light winds and partial sunshine will make for a decent day. We will have to pay attention to the next shortwave, as it could produce either light snow or freezing drizzle overnight Sunday, potentially affecting the Monday morning commute. -- Milder Monday to Wednesday, then a couple chances for moderate rain or snow in the latter half of the week -- Tuesday will likely be the mildest day with southeast to southwest winds. Dewpoints climbing above 32 during the day in Southern Michigan should enable at least a partial meltoff of whatever frozen precip is on the ground. There will be another shortwave moving through which could produce light precip. Two more waves are lined up after that, one for Wednesday night and one for the weekend, but there is considerable disagreement in ensembles for whether precip will occur or whether it will be liquid or frozen. Of the solutions that have precipitation, some of them would have impactful amounts of precipitation (but a lot less than what is occurring this weekend). && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 735 PM EST Sat Jan 11 2020 Widespread IFR conditions are in place at 00z this evening and this will remain the case much of the next 6 hours. Another burst of precipitation will work through the TAF sites between 00z and 06z. The precipitation is currently mainly freezing rain, but this will begin to mix with ice pellets and eventually snow over the next 2 to 4 hours. By 04z-05z the precipitation will be switching over to snow. The snow will then come to an end by 06z or so. Bottom line...IFR conditions to continue for the most part through 06z with improvement after that. Visibility should come up pretty quickly after 06z to VFR, with ceilings potentially lifting to VFR as well by 12z. For the most part Sunday looks dry with VFR weather. The exception might be down along I-94 where MVFR ceilings are forecast by some models in the afternoon. && .MARINE... Issued at 330 PM EST Sat Jan 11 2020 Northeast to north gales continue through tonight, with waves hazardous to small craft lingering into Sunday morning. Some freezing spray possible tonight, before the winds calm down, off the Sable Points. Water levels are up about a half-foot at Holland versus the recent average, due to the wind-driven southward push of water down the entirety of Lake Michigan. Flirting with lakeshore flood conditions tonight around South Haven, but wave heights and the duration of short duration northwest winds tonight before relaxing do not quite reach the magnitude of the past few months` events. && .HYDROLOGY... Issued at 330 PM EST Sat Jan 11 2020 1.5 to 2.5 inches of rain fell overnight across a wide area along and south of I-96, with the highest totals along a line from Kalamazoo to Lansing. This has resulted in ongoing minor flooding due to poor drainage and overflowing small streams and creeks, and some localized flooding issues are expected to continue through the night as the ponded water continues finding its way to the small waterways. An flood advisory is in effect through tomorrow for these areas, as additional mixed precipitation tonight will only prolong these effects. Now attention turns to the medium and large-sized rivers over the next few days as this water works its way downhill. Overall, we are still expecting significant river flooding on some of the upstream portions of the Grand River, and the smaller tributaries around Lansing and Kalamazoo. As the crest works down the Grand and Kalamazoo rivers this week, minor flooding is likely at some of the more vulnerable locations. This includes Ionia, Lowell, Comstock Park, and Robinson Township on the Grand River. With minor additional precipitation amounts expected tonight, these forecasts can and will change over the coming days. Anyone with interests along the rivers in West Michigan needs to pay extra attention over the coming days, especially in the Kalamazoo, Lansing, and Jackson areas. The time is now to prepare for significant water level rises and potential flooding. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Storm Warning until 7 AM EST Sunday for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. LM...Gale Warning until 1 AM EST Sunday for LMZ844>849. && $$ UPDATE...Duke SYNOPSIS...CAS DISCUSSION...CAS AVIATION...Duke HYDROLOGY...AMD MARINE...CAS
Area Forecast Discussion
National Weather Service Wilmington NC
1032 PM EST Sat Jan 11 2020 .SYNOPSIS... Unseasonably mild temperatures will prevail through the weekend with southerly winds ahead of a cold front. Rain chances will increase tonight and Sunday as the front approaches. Wet and mild conditions will continue early next week with the front stalled in the area. Another cold front on Thursday will bring cooler weather late next week. && .UPDATE... Evening update includes severe thunderstorm watch for counties along and west of I-95. Latest radar shows line of thunderstorms to the west of I-95 moving rapidly towards the I-95 corridor with a history of producing damaging winds. Thunderstorm watch is in effect until 2 AM EST. && .NEAR TERM /THROUGH SUNDAY NIGHT/... A few warm advection showers moving north across the region have been hard pressed to lead to measurable rain and that will likely remain the case through sundown. It is then the 00-06Z window during which rain chances increase, though high res guidance like the RAP and HRRR don`t agree as to the exact location. A line of showers is forecast to develop offshore and move into either the Grand Strand area (HRRR) or the Cape Fear region (HRRR); all while rain chances gradually increase from the west. This is also the window of time when wind fields strengthen to the extent that may support isolated tornado spinups despite the overall absence of deep convection. The very narrow ribbon of deep moisture aligns right at the coast towards 12Z but then washes back across our entire CWA for the remainder of the period. Wind fields will have weakened by then but there is a better chance of instability in the 1000-1500 J/Kg range. Thunder will remain in the forecast through Sunday but the severe threat will have shifted well to our north. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... The rapid weakening and northward trajectory of the current system will lead to an interesting scenario for the short and part of the long term periods. The front associated with this system will near the coast before stalling and even moving northwest through the short term period. This is usually a summertime scenario and I`m not sure I have seen this in January. Regardless, showers and even a rogue thunderstorm or two will be fair game through the period. There appears to be little organization to the activity so QPF amounts will be muted and somewhat erratic. The warm thermal profiles remain in place leading to highs in the 70s Monday and lows mainly above 60. && .LONG TERM /TUESDAY THROUGH SATURDAY/... The unsettled nature of the short term period with a broad southwest flow will remain in place for Tuesday and Wednesday. Broad brush chance pops remain in place for these periods but in time the short term and certainly near term periods will offer more detail as the relatively weak forcing is leading to diffuse QPF generation. A cleansing cold front will move across Thursday with dry and cooler conditions developing. Another system could affect the area at the end of the period. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Rain chances increase significantly towards 06Z and some terminals may approach LLWS criteria though the surface winds will remain quite gusty as cold front approaches the region. The main frontal line of showers will enter the area from the west around daybreak Sunday. Though this line will be capable of producing strong winds they will be hard pressed to produce much thunder. Extended Outlook...A stalled front will remain in the area Sunday through Tuesday, accompanied by occasional rain and MVFR ceilings. Very localized sea fog with IFR visibility and ceiling may affect the CRE and MYR airports during onshore wind through Tuesday. && .MARINE... Frontal boundary approaches from the west but also stalls to our west. This will gradually ease the gradient as we progress through Sunday and Sunday night, below advisory thresholds in fact. Seas however will take a bit longer to drop below 6 ft and they will be the deciding factor of when the flags can be lowered. The high dewpoints that have advected into the area should be supportive of sea fog but there is considerable discrepancy between various guidance regarding its onset and severity. Have hedged towards the slower and less severe solutions as the wind will likely have to partially relax to favor its formation. Basically a summertime pattern in place with a southwest flow at most levels through about Wednesday. Winds will be southwest at 10 knots or so while seas will be 2-4 feet with maybe a few five footers mainly early. Sea fog will probably be the main issue for this period as the pattern is conducive for such. A cold front will move across late Wednesday or early Thursday morning with a stronger offshore flow developing. Winds and seas will increase but most likely remain well below any headline criteria. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Severe thunderstorm watch until 2 AM EST Sunday for Marlboro, Darlington, Dillon, and Florence counties, SCZ017-023-024-032 NC...Severe thunderstorm watch until 2 AM EST Sunday for Robeson county, NCZ087. MARINE...Small Craft Advisory until 3 PM EST Sunday for AMZ254-256. Small Craft Advisory until midnight EST Sunday night for AMZ250-252. && $$ SYNOPSIS...SHK UPDATE...MCK NEAR TERM...MBB SHORT TERM...SHK LONG TERM...SHK AVIATION...MBB MARINE...MBB/SHK
Area Forecast Discussion...Correction
National Weather Service Northern Indiana
840 PM EST Sat Jan 11 2020 .SYNOPSIS... Issued at 406 PM EST Sat Jan 11 2020 Rain across the region will change over to a wintry mix of sleet and freezing rain this evening across far northern Indiana and southern Lower Michigan before changing to a period of snow. Light snow and ice accumulations are possible especially along and north of Route 6. Elsewhere rain will change to a brief period of snow late this evening into the early overnight. The potential of heavy precipitation has diminished, but runoff from the moderate to heavy rainfall earlier Saturday will continue to pose a threat of river flooding along with ponding of water on roads and some flooding near creeks, streams, and low lying areas. As this system pulls off to the east tonight, windy conditions are expected to develop with the strongest winds generally along and south of Route 24 across northeast Indiana and northwest Ohio late evening into the overnight. && .UPDATE... Issued at 838 PM EST Sat Jan 11 2020 A changeover to a quick burst of snow and difficult travel still appear likely into nw IN and sw MI this evening as potent mid level wave and associated fgen/deformation response lift northeast into the Lower Great Lakes region. Some heavier banding and steeper mid level lapse rates with the upper low are expected here given upstream radar/ob trends and last several HRRR runs. Have bumped up snow a bit in far nw IN/sw MI where decent snowfall rates could lay down a quick 1-3" between 3-6z. Deformation pivot and erosion of warm layer aloft then does finally bring a brief changeover from rain to snow into ne IN/sc Lower MI/far nw OH between 5-7z with some minor accums/impacts possible. Conditions then quickly dry out between 7-9z. As for winds, the greater isallobaric push in wake of sfc low pressure (deepening to Lake Erie) does look to be shunted south and east of the forecast area which brings the Portland IN to Lima OH Wind Advisory into question tonight. No changes for now but may need to trim this back with the next update. && .SHORT TERM...(This Evening through Sunday) Issued at 406 PM EST Sat Jan 11 2020 The Flood Watch has been allowed to expire as the potential for additional heavy rainfall has diminished. 1 to 3 inches of rain has been reported across many locations past 24 hours which will lead to some minor to moderate river flooding over the next several days. Still some potential of some enhancement to rain across extreme northeast Indiana and northwest Ohio through early evening as approach of this wave interacts with strong low level jet and very slow moving low level frontal zone. Colder air undercutting warm layer has allowed for a mix of rain and sleet to be reported earlier this afternoon across southwest Lower Michigan, and this wintry mix will continue to push southeast through the remainder of the early evening. Forecast soundings still suggest a potential 3 to 6 hour freezing rain potential before low level warm layer atop shallow cold air is eroded. The more favorable profiles for freezing rain still appear to reside north of the Route 6 corridor, with the greatest snow accumulations expected across southwest Lower Michigan where quicker erosion of low level warm layer should favor snow earlier this evening/overnight. Have not changed overall nature of previous forecast in the winter weather advisory area with light ice accumulations one tenth of an inch or less and snow accumulations of 1 to 3 inches across southwest Lower Michigan. One trend that will be watched by evening shift is a tendency in new near term guidance of stronger and slightly slower evolution with the primary upper trough. This could displace deformation forced precip a bit southeast from current forecast. Given the potential of slightly slower kick out of main deformation forcing will extend the winter weather advisory through 09Z. Other concern for tonight will be the potential of at least a short period of very strong winds. Sfc reflection of this system should be in a slightly deepening state as it tracks across northwest Ohio overnight. Near term soundings indicate 40 knot flow a few thousand feet off the ground with a period of isallobaric contribution of strong pressure rises building in behind exiting sfc low. While period of advisory potential may be limited to a 3 hour window, will keep wind advisory in effect for far southeast areas with a few 50+ mph wind gusts possible late evening and early overnight hours. && .LONG TERM...(Sunday Night through Saturday) Issued at 406 PM EST Sat Jan 11 2020 Quiet weather for Sunday as the primary upper trough pulls off to the east and short wave ridging builds into the region ahead of next Pacific wave across the Rockies. This wave will rapidly lift northeast, but relatively shallow moisture profiles in place ahead of this wave should confine any precip chances to mainly drizzle, with better chances north of the forecast area. Have kept cloudy skies in place for Sunday with low level inversion remaining in place. No real opportunity for cold air intrusion behind this wave for Sunday night/Monday as larger scale longwave trough takes shape across western CONUS. This will provide another mild day for Tuesday before this wave passes for late Tuesday/Wednesday. End of week should feature trend to near normal temperatures with higher chances of precipitation by next Fri/Sat. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 622 PM EST Sat Jan 11 2020 Light drizzle/rain will changeover to a wintry mix at KSBN around 01z and KFWA toward 05z, with precipitation ending at each terminal by 07-08z as low pressure exits. There could even be a several hour period of moderate/heavy snow at KSBN as warm layer aloft erodes and deeper moisture/ascent overspread a tightening low-mid level front draped over the region. Covered this threat with a tempo group at KSBN, though confidence in exact placement of narrow banding remains uncertain. Deformation band does pivot through FWA between 05-07z tonight with a period of snow/sleet possible. A quick dusting to 1 inch cannot be ruled out here. Flight conditions will likely remain IFR for most of the evening and early overnight otherwise, with periods of LIFR likely at mainly KSBN. Winds will diminish and precipitation will end by later tonight and Sunday as shortwave ridging overspreads. MVFR cigs will likely hang in though as moisture lingers within a strengthening subsidence inversion. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Wind Advisory until 4 AM EST Sunday for INZ027-034. Winter Weather Advisory until 4 AM EST /3 AM CST/ Sunday for INZ003>007. Lakeshore Flood Advisory until 6 AM CST Sunday for INZ003. MI...Winter Weather Advisory until 4 AM EST Sunday for MIZ077>081. Lakeshore Flood Advisory until 7 AM EST Sunday for MIZ077. OH...Wind Advisory until 4 AM EST Sunday for OHZ015-016-024-025. LM...Gale Warning until 4 AM EST Sunday for LMZ043-046. && $$ UPDATE...Steinwedel SYNOPSIS...Marsili SHORT TERM...Marsili LONG TERM...Marsili AVIATION...Steinwedel Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
919 PM EST Sat Jan 11 2020 .SYNOPSIS... Low pressure will move northeast from the Ohio Valley into the Great Lakes tonight. The cold front associated with the low will pass through our area overnight into early Sunday morning. High pressure will return for later Sunday, but the cold front will stall, then return north as a warm front for the early and middle portion of next week. Unsettled conditions are possible during this time. && .NEAR TERM /UNTIL 7 AM SUNDAY MORNING/... Negatively tilted shortwave is lifting across the Ohio Valley this evening with associated surface low over Ohio. CAMs have been handling the northern edge of convection fairly poorly, so evolution is of low confidence for the remainder of the night. Persistent bowing segment approaching from the southwest may try to weaken as it reaches our area as it outraces the best instability. Recent HRRR runs generally paint this trend in the ongoing convection. However, it`s still possible this isn`t the "main show" with additional development ahead of the approaching surface trough late tonight (scenarios outlined below are still generally valid). Low level jet will transport moisture/CAPE ahead of this boundary, making the resurgence possible. Forecast 0-1km CAPE, 0-500m shear, and (relative lack of) surface based CIN near the convection suggest strong to severe winds could make it to the surface if organized convection can develop AND orient in a SW>NE direction (perpendicular to low level shear vector). The best overlap of these parameters are generally along our southern border in the Fredericksburg vicinity. While a brief QLCS tornado can`t be ruled out due to low level shear, this seems like a low probability, and CAMs show little in terms of updraft helicity tracks. With shallow/weak instability, it`s possible severe weather could occur without lightning, so people should make sure they have a way to be alerted to warnings given the overnight timing. Previous discussion: Winds remain gusty out of the south, though they have decreased a bit with sunset. That may not be the case as the night progresses, as the LLJ will gradually strengthen through the remainder overnight hours as the system approaches from the west, ultimately reaching near 70 knots at 850 hPa by around 06z. With a near moist-neutral profile in place, the highest winds aren`t expected to mix down to the lowlands outside of any enhanced areas of convection. However, higher winds winds are expected in background southerly flow over the ridgetops as the LLJ strengthens. Winds Advisories have been issued for the Blue Ridge and higher elevations near the Allegheny Front to account for these higher winds. Moving into the overnight hours, the main shortwave will lift from the lower MS Valley toward the OH Valley by 06z, eventually tracking across the eastern Great Lakes/Upstate NY by 12z. As this occurs, the zone of mid-upper level forcing for ascent and associated area of precipitation are expected to translate toward the north and east. What remains of the squall line(s) currently stretching from the OH Valley southward to the Gulf of Mexico is expected to reach western portions of our forecast area (Allegheny Front) around midnight, then track eastward across the Mid-Atlantic through the overnight hours. There are mixed signals in the CAM guidance with respect to what will happen with this line as it moves eastward into our area. There are a few potential scenarios that could occur: 1. The leading edge of the squall line and trailing area of stratiform rain holds together across the Appalachians and tracks across our area intact. In this scenario, we`d have a low end threat for some stronger wind gusts along the leading line. 2. The leading edge of the squall line weakens or outright falls apart as it encounters the higher terrain/tracks away from the strongest forcing for ascent. In this scenario, the region of stratiform rain would still work across the area, but the threat for damaging wind gusts would be minimized. 3. The leading edge of the squall line weakens or falls apart as it crosses the mountains, but additional redevelopment of storms occurs to the east of the Appalachians. This scenario was depicted by some of the HRRR runs throughout the day. A few of these runs had additional redevelopment occurring behind or within the stratiform rain area, but ahead of the surface cold front, while others showed the redevelopment taking place immediately along the surface cold front. In this scenario, the best chance for strong wind gusts would be within the areas of secondary redevelopment. Continued warm advection in southerly flow will keep conditions warm overnight, with temperatures holding in the 60s and dewpoints climbing well into the 60s ahead of the line. The combination of mid 60s temps and dewpoints will result in limited instability at the surface. The 12z HREF ensemble mean shows 100-300 J/kg of surface based instability streaming northward to the east of the Blue Ridge immediately in advance of the line, with very limited to no surface based instability to the west of the Blue Ridge. High values of shear will be present across the entire area, with 0-1 km shear values climbing to near 60 kts as the core of the LLJ slides overhead. With the strong LLJ in place just off the surface, current thinking is that the primary threat will be isolated damaging wind gusts in association with stronger convective elements that are able to bring those higher winds from aloft down to the surface. Damaging wind gusts would be most likely with any line segment whose motion is southwest to northeast, orthogonal to the LLJ. However, the moist neutral profile will temper this potential somewhat. Can`t completely rule out a brief spin up either given limited instability and extreme values of SRH of 500-700 m^2/s^2. The best synoptic scale forcing lifting to the north of our area (as well as the time of day and the time of year) will be a major limiting factor. Precipitable water values will surge to well in excess of 1.5 inches ahead of the line (which could be outside the observed range of January PW values in the IAD sounding climatology; max is 1.64"). With this high PW air in place, heavier downpours can`t be ruled out in any stronger convective elements. However, we aren`t expecting any flash flood or flood issues given the relatively short duration of the precipitation and fast storm motion. && .SHORT TERM /7 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Any precipitation should clear the area by around daybreak, with the surface cold front clearing the Chesapeake Bay by early to mid morning. Winds may remain elevated for a few hours behind the front in westerly flow, but should subside rather quickly by the afternoon hours. Skies will be mostly sunny with temperatures holding in the 50s to the west/60s to the east as cold advection aloft offsets solar heating at the surface. Given the lack of appreciable cold air advection immediately behind the front and downsloping W/NW flow, temperatures may eclipse 70 F once again. The cold front from tonight`s system will stall to our south, and could potentially return north as a warm front by late Monday into Monday Night in response to a disturbance tracking to our north. Model guidance differs on the northward progression of the front, but there could be a few showers across far southern portions of the forecast area Monday Night. Temperatures will continue to run well above normal for January, with high in the 50s to near 60 on Monday. && .LONG TERM /TUESDAY THROUGH SATURDAY/... A stationary front across southern Virginia will meander north and south Tuesday through Wednesday. This front will bring some light rain northward into our region Tuesday before the rain becomes more showery Tuesday night and Wednesday. Temperatures will be above normal for mid-January during both days and at night. By Wednesday night, the western end of the stationary front will get a little push northward as it links up with low pressure over the lower Great Lakes. The low pressure will move eastward toward southern New England Wednesday night and Thursday. A developing cold front on the southwest flank of the low will drag across our region Thursday and Thursday night. Limited moisture ahead of the cold front appears keep chances of rain showers minimal for now. The pattern will begin to flip by the end of the week as strong, cold high pressure fills in behind the cold front bringing colder-than-normal air southeastward into our region. Dry conditions will ensue during the day Friday. As for late Friday through early Saturday, the cold dome of high pressure will build southward along the eastern slopes of the Appalachian Mountains. There is a chance that most of us could see a mix of rain and snow with this cold air anchoring into the region and some overrunning moisture pushing in from the southwest. The 12Z ECMWF/GFS/CMC all agree on this, but given the time range and inherent ensemble spread this far out, it is too early to tell in terms of rain or snow amounts, but at the very least it looks unsettled during this time. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Gusty south winds to 30 kt continue this evening with ceilings lowering into the MVFR range. Am thinking IFR potential is low, except at CHO, and as any heavier rain showers arrive later tonight. A few light showers are possible this evening, but shouldn`t reduce visibility appreciably. Low level wind shear is likely ongoing as well with 44 kt measured at 2000 ft. A line of showers and potentially even a thunderstorm or two will move across the area later tonight. The most likely time for this activity to move across the metro terminals will be between 07Z and 10z, although the evolution could be messy and is uncertain. CHO could see convection much earlier. Briefly higher winds will be possible with any stronger convective elements that move over the terminals. Vsbys could briefly drop to to IFR or LIFR in any heavier downpours, as well. The surface cold front associated with the system should clear the terminals by daybreak. Conditions will return to VFR behind the cold front, and winds will become westerly. Winds could be gusty for a few hours early tomorrow morning, but will subside through the course of the day. VFR conditions are then expected on Monday. Drops to sub-VFR can`t be ruled out Monday Night with a stationary boundary in place to our south, especially at CHO. Sub-VFR conditions possible at CHO, DCA and IAD Tuesday with rain on the north side of a stationary front wavering over south- central Virginia. Elsewhere, VFR conditions are most likely. VFR conditions are expected at all terminals Tuesday night with a few showers around, with VFR likely again Wednesday and Wednesday night. && .MARINE... A cold front will approach tonight and pass to the east Sunday morning. Ahead of this front, southerly winds are gusting 20 to 30 knots. An isolated gust to near 35 kts is possible. Small Craft Advisories have been issued to cover this. A line of showers and a few thunderstorms is expected to move across the waters very late tonight into very early Sunday morning. As of now, it appears as though the most likely time window for the line to impact the waters will be between 4 AM and 7 AM. As this line of storms passes through, Special Marine Warnings may be needed. Locally reduced visibility in fog is also possible as very warm, moist air moves over the colder waters. After the cold front moves past our waters, a few hours of SCA gusts will be possible in westerly flow, especially across northern parts of the Bay. Winds are expected to subside through the late morning hours and into the afternoon, with conditions dropping below SCA levels by mid to late afternoon. Sub-SCA level winds are then expected on Monday as the aforementioned front stalls to the south. No marine hazards are expected Tuesday through Wednesday. Small Craft Advisories may be needed Wednesday night in strengthening southerly flow ahead of low pressure approaching from the west, but questions remain relating to mixing given warm air over relatively cooler water. && .TIDES/COASTAL FLOODING... Strong southerly flow will continue ahead of a cold front through Sunday morning. The flow is just west of due south, though, resulting in a slight offshore component, especially near the mouth of the Chesapeake Bay. As a result, virtually all available model guidance keeps tides below minor thresholds through tomorrow, and current trends support this. Some caution stages could be reached. Winds become westerly behind said cold front Sunday, resulting in decreasing water levels. ETSS/ESTOFS/Snap-Ex show tides dropping to a foot below MLLW by Monday morning, but am a pinch skeptical of this outcome given a lack of particularly strong northwest flow. && .CLIMATE... Well above normal temperatures are expected this weekend. Daytime highs are forecast to be 20-30 degrees above normal today and Sunday. Temperatures tonight are expected to be 30 to 35 degrees above normal. Record daily warm temperatures are possible. As of now, it appears that the record highs are a bit higher than our forecasts, but it could be close. For reference, the record daily warm temperatures (highs/lows) for January 11th and 12th are listed below: Record Daily High Temperatures for January 11th: Washington DC area: 75 F (set in 1975) Baltimore MD area: 73 F (set in 1975) Sterling/Dulles VA area: 71 F (set in 1975) Record Daily Warm Low Temperatures for January 11th: Washington DC area: 56 F (set in 1975) Baltimore MD area: 48 F (set in 1975) Sterling/Dulles VA area: 45 F (set in 1975) Record Daily High Temperatures for January 12th: Washington DC area: 76 F (set in 1890) Baltimore MD area: 70 F (set in 2017 and 1890) Sterling/Dulles VA area: 70 F (set in 2018 and 2017) Record Daily Warm Low Temperatures for January 12th: Washington DC area: 57 F (set in 2018) Baltimore MD area: 53 F (set in 2018) Sterling/Dulles VA area: 58 F (set in 2018) && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Wind Advisory until 5 AM EST Sunday for MDZ501. VA...Wind Advisory until 5 AM EST Sunday for VAZ503-504-507-508. WV...Wind Advisory until 5 AM EST Sunday for WVZ501-503-505-506. MARINE...Small Craft Advisory until noon EST Sunday for ANZ530>543. && $$ SYNOPSIS...DHOF NEAR TERM...ADS/KJP SHORT TERM...KJP LONG TERM...KLW AVIATION...ADS/KLW/KJP MARINE...ADS/KLW/KJP TIDES/COASTAL FLOODING...ADS/DHOF CLIMATE...DHOF
Area Forecast Discussion
National Weather Service Omaha/Valley NE
855 PM CST Sat Jan 11 2020 ...Updated Discussion For Sunday Snow Forecast... .UPDATE... Issued at 825 PM CST Sat Jan 11 2020 New observation and model data this evening largely supports the existing forecast for the Sunday time frame. Thus do not expect any substantial updates this evening, and this remains likely to be a sub-advisory event with most areas receiving less than 2 inches of snow on a relatively light travel day with minimal wind. That said, light snow on cold roads still gives reason for caution in any travel on Sunday. At 830 PM, the storm system of interest was centered over Utah with a weaker lead wave over north central Colorado and jet streak entering southeast Colorado. Mid and upper level radar echoes were increasing in coverage over northeast Colorado. Cloud bases were above 8000 feet in northeast CO and above 20000 feet in SW NE...and while steadily decreasing, there have not yet been any snow reports in the Plains. 00 UTC OAX sounding indicated substantial dry air through much of the vertical profile, and while low/mid/hi water vapor imagery indicates moisture advection from the west, the LBF and Denver soundings are not exactly swimming in atmospheric moisture so it appears that much of the saturation for eventual snow production will have to be accomplished through lifting parcels. Lift increases by sunrise, especially in northeast Nebraska, but will probably see elevated radar echoes long before it reaches the surface. Still some hints at slightly banded precip in this area, but it will all depend on speed of saturating the column. Much better vertical motion moves into the area by late morning or early afternoon with the main wave and widespread light snow remains likely at that time. 00 UTC model data suggests that the NAM remains over-ambitious with QPF while the RAP may be in a similar boat given recent biases along with observational factors already mentioned. HRRR is on the low end of the model spectrum while the Hires ARW/NMM represent the existing forecast pretty well. QPF aside, the modest vertical motion and limited supersaturation of the profile suggest that perhaps snow ratios will be on the lower end of what might normally be expected in such a cold profile. All food for thought in this forecast, and don`t see a need for any significant updates to the existing forecast, nor any need for an advisory at this time. && .DISCUSSION... Issued at 219 PM CST Sat Jan 11 2020 Forecast Summary: Progressive weather pattern will continue through the forecast period with several impulses bringing light snow chances through next Saturday. The first could drop up to three inches in northeast Nebraska on Sunday. With the exception of Monday,temperatures will remain below normal through the week. Through Sunday: Shortwave currently diving through the Pacific Northwest is forecast to translate through the Rockies overnight and sharpen as is emerges into the Plains Sunday morning. Diffluent flow ahead of system will lead to decent isentropic upglide along 290K surface as low level jet increase to 30-40kt from Kansas into eastern Nebraska. Forcing for ascent shown by converging Q-vectors through a deep layer of the atmosphere will spread across our forecast area between 12Z and 21Z on Sunday. Initial dry low levels should be saturated early in the day in our north and by noon and later as we head south toward the Kansas and Missouri borders. Forecast soundings and cross sections suggest maximum upward motion will best align with with dendritic growth zone across our northern CWA where more efficient snow production is expected. Specific humidity calculations using Garcia method to approximate maximum snowfall would indicate some 3 inch amounts are possible in our north given an 8-hour event, with lesser duration/lift suggesting amounts taper to little if anything in our south before snow ends by early Sunday evening. Monday through Thursday: A fairly progressive mid level pattern sets up much of next week as weak shortwaves march east through broad trough covering the western two-thirds of North America. Two such shortwaves will affect our area late Monday afternoon and evening, and Tuesday night/Wednesday periods. Both systems will have relatively limited moisture available for precipitation, and look to mainly affect our northern CWA. Still an inch or so of snow could fall with each system. Perhaps of greater impact will be colder temperatures invading for mid week. Temperatures warm nicely Monday ahead of first shortwave, with temperatures expected to climb into the 30s. Colder air in wake of this system will knock back temperatures a bit for Tuesday, but stronger cold advection following Tuesday night and Wednesday system will push highs back into the teens and 20s by Thursday. The magnitude of this cold outbreak has been tempered over the last few model runs as brunt of arctic air remains in southern Canada and the Northern Plains. Thursday night through Saturday: Mid level trough deepens in the West Thursday night, strengthening southwesterly flow across the Plains. A potent southern stream shortwave is advertised to eject ahead of that trough into our region Thursday night and Friday, picking up Gulf moisture as it approaches. This could pose a problem as forecast soundings show warm air aloft over shallow sub-freezing boundary layer, leading to potentially significant freezing rain for the southeast half of our forecast area before increasing southeasterly low level flow and latent heat release from precipitation can warm temperatures above freezing. This is still a ways out and there is discrepancy between models, but certainly something to watch out for. Otherwise there is a potential for snow over northern Nebraska Friday morning where cold air is deeper, then over the rest of eastern Nebraska and southwest Iowa Friday night into Saturday when western trough migrates through the Plains. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 540 PM CST Sat Jan 11 2020 VFR conditions and winds less than 10kts are expected at all TAF sites through at least 12 UTC. While the breeze may initially be out of the north, it will turn out of the east or southeast before sunrise at all sites. Expect snow to begin at OFK between 14-16 UTC with IFR visibility likely shortly after onset. LNK and OMA will have snow begin later, likely in the 19-22 UTC range, with a quick decrease to IFR visibility when snow begins there as well. Minor snow accumulation is likely with snow ending near 00 UTC. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ UPDATE...Barjenbruch DISCUSSION...Dergan AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Tulsa OK
931 PM CST Sat Jan 11 2020 ...UPDATE... .DISCUSSION... Clearing has been slow this evening, although back edge of low clouds continues to show gradual progress east. Will follow trend of clearing skies the remainder of the night, although parts of extreme northeast OK into northwest AR may be the last to clear per recent HRRR output. && .PRELIMINARY POINT TEMPS/POPS... TUL 20 53 33 62 / 0 0 0 0 FSM 21 55 32 63 / 0 0 0 0 MLC 22 54 35 63 / 0 0 0 0 BVO 14 52 25 61 / 0 0 0 0 FYV 16 51 28 59 / 0 0 0 0 BYV 20 51 35 60 / 0 0 0 0 MKO 20 52 32 61 / 0 0 0 0 MIO 17 50 30 60 / 0 0 0 0 F10 21 54 33 63 / 0 0 0 0 HHW 24 54 36 63 / 0 0 0 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18