Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/09/22

National Weather Service Albany NY
919 PM EST Thu Dec 8 2022 .SYNOPSIS... Clouds gradually clear tonight giving way to a chillier night. Expect abundant sunshine tomorrow with seasonably cool temperatures and a slight northerly breeze. Sunshine on Saturday will slowly fade behind increasing clouds late Saturday into Saturday night. Our next disturbance arrives Sunday into Sunday night resulting in a period of snow and light snow accumulations which may give us slippery travel conditions. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 915 pm, stratus remains trapped over the western Adirondacks, with a few patches also around the Lake George Saratoga area and eastern Catskills. Updated sky grids to reflect a more pessimistic scenario for the next several hours over the ADKs; otherwise, no changes needed. Previous discussion... Cloudy skies this evening will gradually give way to clearing; however, guidance still suggests clouds linger in western New England and into parts of the Capital Region and the eastern Catskills. Temperatures will likely be contingent on cloud coverage meaning where clouds can clear out (likely southern/western Adirondacks and Upper Hudson Valley) temperatures will fall well into the 20s and even upper teens. Where clouds are stubborn to erode, temperatures will stay a bit elevated and may only fall into the mid to upper 20s. Adjusted cloud coverage to better match the high resolution guidance (i.e HRRR and NAM) which is catching on to the fact that clouds may linger in parts of the region. Otherwise, northwest winds shift to the north and decrease to under 5kts. Northerly flow will help funnel cooler and a much drier air mass into eastern NY and western New England. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... Quiet and seasonably cool temperatures will ensue for Friday and Saturday as high pressure centered near the Hudson Bay in Canada strengthens impressively towards 1045 - 1050hPa. Despite the center of the high displaced well to our north, it will nose southward into the Northeast. Under the influence of the high, expect abundant sunshine tomorrow throughout the day with northerly winds funneling seasonably cool and very dry air down the north-south oriented Champlain and Hudson Valley. With a coastal low off the New England coast, the pressure gradient overhead will tighten resulting in slightly breezy winds, especially down the valley, ranging 5 - 10kts with gusts up to 15-20kts at times. Clear skies and northerly flow continuing to funnel chilly and very dry air down the valley will likely result in a cold night Friday night. We trended temperatures downward compared to the NBM guidance given the clear skies and northerly flow. Normally clear skies and any kind of wind usually impedes temperatures from cooling as much as they could but in this situation, the northerly winds will be advecting in a chilly air mass. Thus, we felt confident enough to blend in NBM25th percentile and trend temperatures lower. Dew points in the teens and clear skies will also assist cooling. We show lows reaching into the mid to upper teens with near 20 degrees in the valley. The MET/MOS guidance actually show even cooler values in the low to mid teens but we did not feel confident to go that cold given the somewhat breezy winds. Sunny skies and chilly temperatures continue into Saturday as the ~1045hPa maintains control. The low subsidence inversion height will likely limit boundary layer mixing and thus keep high temperatures seasonably cool with highs in the mid to upper 30s despite the sunshine. Luckily, the pressure gradient relaxes so northerly winds will be weaker compared to Friday. Clear skies Saturday night will gradually fade behind intruding cirrus clouds from southwest to northeast. Temperatures should not be as cold as Friday night but still end up chilly from radiational cooling during the first half of the night (especially for areas north of I-90 where skies stay clear longer). Expect lows in the low to mid 20s with upper teens in the southern Adirondacks where radiational cooling will have a longer influence. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Main focus for the long term is a system that will bring a period of light snow to the region Sunday and Sunday night. Then, the first half of next week loos tranquil and dry with below normal temperatures. Another weather system is possible towards the end of next week, but confidence is low surrounding this system. More details below... Long term period begins Sunday with a strong 1040+mb surface high located over Quebec, with a surface pressure ridge extending southwards into our region. At the same time, an uper-level disturbance and associated area of low pressure will be tracking across the Great Lakes Sunday and over our region Sunday night. This clipper system should have enough moisture and forcing for ascent (cyclonic vorticity advection, left exit of an upper jet streak over our area) to produce a light snowfall for much of the region. It is still early to talk about snowfall amounts, but a general 1-3/2-4" snowfall seems plausible. Some rain may mix in in the valleys during the afternoon, but all areas should see a change to snow by the evening, so even valley areas could see light snowfall accumulations. Onset timing of snow looks to range from mid-day in the western Mohawk Valley to mid to late afternoon in western New England. Now, there are still some forecast intricacies that have to be ironed out. First, as the upper disturbance emerges over the Atlantic ocean Sunday night, the primary low will weaken and a new surface low forms off the Mid-Atlantic coast. A Norlun/inverted trough is expected to extend back from the coastal low towards the decaying primary low, which will become vertically stacked beneath the upper low. Locally heavier snow is possible with this feature, but where exactly this feature sets up remains uncertain, and these inverted troughs often end up further south than modeled. Additionally, recent forecast trends have been for more amplified ridging over the center of the country, which would lead to a further north track of the surface low. The other feature that will need to be monitored is a closed upper low diving southwards over southeast Atlantic Canada on Sunday. If this feature is faster/further south, then it could force the clipper system to track further south, potentially limiting snowfall accumulations for northern areas. At this time, will continue to mention light snowfall, with a few areas potentially needing winter weather advisories. Highest confidence in accumulating snow remains for areas along and south of I-90. As the system pulls away from our area Monday, a ridge of high pressure builds back into the region from the north. This will result in cool but tranquil weather for the first half of the week. Then, a more impressive storm system may approach the region towards the end of the week, but due to low confidence will just mention chances for rain and snow at this point in time. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Through 00z Saturday...A ridge of high pressure building over the region from the north will result in dry and tranquil weather through at least the end of the TAF period. FEW to SCT mid-level clouds are expected through tonight, especially at GFL and PSF, but still expecting conditions to remain VFR. Tomorrow morning, any mid- level clouds dissipate during the morning with clear skies through at least 00z. Winds will be at 5-10 kt from the north/northwest at all TAF sites tonight, then will become more north/northeasterly at 5-10 kt through the day tomorrow while remaining northwesterly at 5- 10 kt at PSF. Outlook... Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Likely SHSN...SN. Sunday Night: High Operational Impact. Likely SHSN. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Speciale NEAR TERM...Thompson/Speciale SHORT TERM...Speciale LONG TERM...Main AVIATION...Main
Area Forecast Discussion
National Weather Service La Crosse WI
518 PM CST Thu Dec 8 2022 .DISCUSSION...(This evening through Thursday) Issued at 246 PM CST Thu Dec 8 2022 Key Messages: - Mixed precipitation, while slightly later than previous forecasts, still on track for late tonight lasting into Friday. - Light precipitation chances lingering through Saturday. Minimal accumulations possible with less than 1" of snow to a light glaze of ice. - Monitoring the impending system for early/mid next week. Several details still need to be worked out, but this rain/snow/wintry mix system has the potential to be fairly impactful for the region. This Afternoon: Water vapor satellite imagery exhibits cyclonic circulation lee of the Rocky Mountains with an equatorward subtropical jet propagating it eastward; deadset on the Upper Mississippi River Valley. Quite a steep low level temperature inversion this morning over the forecast area evident in neighboring 12Z soundings and the local ARX webcam trapping boundary surface exhaust. Vad Wind Profiles from neighboring profiles have anticyclonic flow centered over the hat of Illinois. As this anticyclonic flow shifts downstream with the aforementioned progressive upper level pattern, low level warm air advection ramps up and winds turn southwesterly as the warm sector of the impending low affects the forecast area. Where the warm sector is as of 12Z (OAX), a stout low level entrained dry air layer has been inhibiting initial reflectivities. Estimated Time of Arrival: This entrained dry air expected to be in place over our forecast area as initial precipitation shield traverses Iowa later tonight. As saturation occurs, temperature profile expected to dip below the 0C isotherm, limiting initial icing impacts. Have decreased initial freezing rain mentioning and messaging in current forecast. Also have delayed initial onset/advisory by a couple of hours with updated guidance. Increased Snowfall: According to high resolution ensembles, highest confidence for snowfall rates above 1"/hr will occur near the IA/MN boundary from 4am in our western counties to 10am in our eastern counties. Deterministic high res models vary spatially by about a county thickness, potentially placing this increased snowfall band from interstate 90 to Nrn Floyd/Chickasaw counties. National Blend snow ratios have been trending a little low !7:1), therefore have increased slightly to near 10:1 which is climatologically average. This band would be tied to the best low level fgen lobe upstream of the surface low. This band is currently (20Z) shifting north across northeast NE. Drizzle/Freezing Drizzle concerns: As the low passes into Friday morning, upper/mid level dry air erodes ice nucleation falling out of central Minnesota. Therefore, have increased and introduced drizzle/freezing drizzle in weather grids based on high resolution soundings and lack of NBM ice nucleation. RAP (08.15Z) analysis keeps low level moisture (0-1.5km) through Friday afternoon, with passing omega providing moderate forcing. Later into the early evening , subsidence and passing positive omega likely to inhibit drizzle. Have scooted drizzle out to the southeast as it erodes from northwest to southeast. Tonight`s Storm Summary: Similar to previous forecasts, anomalous water content, 90th percentile PWATs, entering the forecast area late tonight and lasting into tomorrow providing higher snowfalls. The deformation band and its attendant fgen band will produce increase snowfall rates from northeast Iowa into southwest Wisconsin late tonight to early tomorrow morning. Overall snowfall amounts will be a few inches for our southern counties. Limited residence within the primary -12 to -18C DGZ zone will limit intensity but we the second DGZ near 0C will provide big, wet flakes. Will be a wet, compactful snow so may be difficult for higher measurements to come to fruition. As the snow exits, drizzle/freezing drizzle concern increases with loss of ice Friday late morning. Should fall on already fallen snow across most of the area, ideally minimizing freezing on roads impacts and again compacting snowfall limiting higher measurements. Friday night - Saturday: Light precipitation accumulations As this system exits the region it fills and lifts into the general flow pattern. Lingering shortwave trough energy from this system will result in precipitation chances to continue through the overnight. The broad isentropic ascent with decent low level saturation as suggested by forecast soundings will support drizzle as the main liquid precipitation type. Cannot rule out some patchy areas of freezing drizzle with surface temperatures below freezing, but once ice gets reintroduced aloft then snow would be expected. Precipitation chances increase into the day closer to 30-40% with an increasing frontogenetic forcing as a longer wave trough slides eastward through the northern plains pushing a surface boundary through the area. Overall, the accumulations will be light, especially compared to the previous system. The highest snow amounts across north central Wisconsin north of I-94 are still anticipated to be less than 1". Weekend travelers should still be aware of potential lingering impacts in wake of the Friday system, but even a light glaze of ice would case issues. Early/Mid next week: Next impactful system targets the region While much of the focus has been on tonight`s impactful winter weather system, there has already been plenty of discussion for an anticipated impactful system early next week. Looking at the big picture a low pressure system is slated to slide southward along the west coast over the weekend. As the associated upper long wave trough edges through the Rocky Mountains, the surface low developing on the leeward side begins on its eastward track towards the region pushing through over midweek. There are still plenty of specific details (timing, location, precipitation type) that will be hammered out as the event draws closer with varying differences among the model guidance. Will be looking at the model trends to see if there is a strong signal on which solution appears to be more favored, but will stick with the blended model guidance as details will continue to be refined over the next several days. Specifically looking the deterministic GFS guidance, the 08.12z run has the system track further to the south and delayed when compared to the previous 2 runs which would hint for more snow accumulations across the region falling more under the cold/northern sectors of the system. Now looking at the GEFS guidance, the probabilities have increased (low end teens to up to 30%) from the previous run across the forecast area for impactful (4+") snow accumulations. However the deterministic EC remains fairly similar to the previous run with the low center tracking from central Iowa through the Wisconsin/Illinois border. The EPS guidance has tightened the snow total gradient compared to the previous run keeping the probabilities nearly the same across the region leaving the highest chances off to the northwest. The track of the system will play into the precipitation type the area receives from this messy wintry mix system. Precipitation chances will be on the decline the further away the system moves heading into the end of the week. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 515 PM CST Thu Dec 8 2022 Low-level clouds will increase in coverage across the area this evening ahead of a quick-moving system that will bring a round of snow tonight followed by light freezing drizzle as the system departs Friday morning. Snowfall onset time has shifted back with this forecast and so has the transition to freezing drizzle. Will leave freezing drizzle out of LSE TAF as it falls near the end of the period, will reexamine the need for fzdz at the 06Z forecast. Conditions are expected to remain on the cusp of MVFR/IFR at LSE through much of the night before they deteriorate into IFR early Friday morning. Visibilities are expected to fall to IFR as a round of snow shifts over the terminal Friday morning. There is a 40% chance for a brief window of LIFR where snowfall restricts visibilities further around 12-15Z. At RST, IFR ceilings are ongoing at the start of this TAF period. These conditions will remain through the night, though there is a 35-40% chance of LIFR ceilings between 3-6Z tonight. Upstream observations at KEST and KMJQ support these chances, but other terminals upstream are around 5-700 feet ceilings. Ceilings may go back and forth between LIFR and IFR for a few hours at RST overnight and have included a tempo group for this chance. Chances are higher (62%) at RST for visibilities to fall into LIFR than at LSE (40%) on Friday morning during the heavier snowfall. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory from midnight tonight to 3 PM CST Friday for WIZ032>034-041>044-053>055-061. MN...Winter Weather Advisory from 9 PM this evening to noon CST Friday for MNZ086-087-094-095. Winter Weather Advisory from midnight tonight to 3 PM CST Friday for MNZ079-088-096. IA...Winter Weather Advisory from 9 PM this evening to noon CST Friday for IAZ008>011-018-019-029-030. && $$ DISCUSSION...Peters/JAR AVIATION...JAW
Area Forecast Discussion...Corrected
National Weather Service Detroit/Pontiac MI
656 PM EST Thu Dec 8 2022 .AVIATION... Conflicting guidance exists with regards to the persistence of MVFR stratus across Southeast Michigan tonight and into the day Friday. MOS is in strong disagreement and much lower on potential for cloud than both the saturation within the deterministic model soundings and HREF probabilities for low cloud. Preference sides with a more pessimistic perspective keeping MVFR OVC throughout the period given structure of inversion and relatively moist easterly flow. A rapidly weakening shortwave will push towards Southeast Michigan from the west after 18Z Friday. Model trends are backing off on the coverage of activity here in Southeast Michigan. Have pushed the PROB30 group back in time until after 01Z. East flow of 10 to 20 knots expected late Friday. DTW THRESHOLD PROBABILITIES... * Medium for ceilings at or below 5000 ft tonight through Friday. * Moderate for ptype as rain/snow mix Friday evening. && .PREV DISCUSSION... Issued at 307 PM EST Thu Dec 8 2022 DISCUSSION... The high pressure system located across nrn Ontario and Quebec is forecast to strengthen during the night. This will reinforce shallow cold air advection across Se MI and will maintain the deep low level inversion noted on the 12Z DTX sounding. While there has been some clearing across NE Lower Mi, the low level flow (now divergent in NE Lower) will turn more north-northeasterly off Lake Huron. The added lake moisture flux under the inversion should sustain ample stratus through the night, limiting the degree of nocturnal cooling to the upper 20s/low 30s. An upper wave now over the central Rockies is forecast to move to the WI/IL border region by early Friday afternoon, then track across Lower Mi late Fri afternoon and evening. While there is strong model support showing this wave remaining a compact mid level low as it approaches the western Great Lakes on Friday, there is a decent spread among various model solutions in depicting how quickly this wave dampen/shears apart as it slides across Lower Mi late Fri/Fri night. The NAM/Canadian/ARW are faster in dampening this wave. The result is that these solutions weaken the ascent significantly by the time the mid level height falls advance into Se Mi. So the moisture transport and ascent is not adequate enough to overcome the wedge of mid level dry air associated with the large anticyclone to the northeast, thus barely bringing any precip at all to Se Mi. The GFS, ECMWF and latest HRRR are slower in weakening this wave, which results in a more compact system traversing srn Mi. These systems maintain a decent moisture surge into Se Mi within a layer of good mid level system relative isentropic ascent. This ascent would overcome the mid level dry air and result in a period of precipitation late Fri afternoon through Fri evening. Noting a weaker trend in both the 12Z GFS and ECMWF, the afternoon forecast will not veer too significantly from the previous one with respect to the better precip chances being southwest of a Saginaw to Mount Clemens line. Overall, precip chances will simply be lowered slightly. Obviously, even though this event is only 24-32 hours out, there is still a fair amount of model spread over Se Mi and additional forecast adjustments are likely. Based on forecast wet bulb zero heights on GFS soundings, precip type will be mainly wet snow. Warm ground temps, boundary layer temps expected to hold in the 30s and compaction still only justifies minimal snow accums (if any) for late Friday at this time. Mid level subsidence will ensure a dry (albeit cloudy) day on Saturday. Another mid level wave forecast to emerge in the lee of the central Rockies is forecast to evolve into a closed mid level circulation as it rotates into the Great Lakes Sat night into Sunday. Expect there will also be additional model adjustments with this system over the next few model runs. Current indications are that the better moisture transport will be deflected south of the state. Respectable mid level height falls will still however warrant precip chances. There will not be as much wet bulb cooling influences from the high parked over nrn Quebec with this second system. So boundary layer temps within this event will be more favorable of a rain/melting snow mix, with a little colder thermal profiles favoring all snow across the Saginaw Valley and thumb region (with some minor accumulations possible). MARINE... A high pressure system will wash out across western Quebec tonight with a secondary high pressure system then filling in across Ontario through Friday morning. This will bring continued light winds for the remainder of the day. A low pressure system is then expected to travel from the Plains into the Ohio Valley through tomorrow afternoon and evening, which will strengthen the pressure gradient, resulting in an uptick in wind speeds and gust potential, between 20 to 25 knots. The placement of the low will reinforce easterly flow which will bring elevated wave action to the shorelines, especially across Lake Huron. A Small Craft Advisory for waves will be likely for portions of Lake Huron and Lake Erie Friday evening into Saturday as a result. Wind speeds gradually diminish late Saturday into Sunday as low pressure vacates the region. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....CB DISCUSSION...SC MARINE.......AM You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Wilmington NC
959 PM EST Thu Dec 8 2022 .SYNOPSIS... Surface high pressure will prevail through early next week, although a few upper disturbances will bring a few chances of rain. A stronger storm system could then impact the area for the middle of next week. && .UPDATE... MVFR ceilings hold over the area with the exception of some clearing along Horry`s coastal terminals. Obs show MVFR ceilings around, and these should start to fill in within the coming hours. Precip to the west will also start to move into the area within the next couple hours. Otherwise, forecast appears to be on track. && .NEAR TERM /THROUGH FRIDAY/... E-W oriented surface front remained located near CHS early this afternoon, with a shallow and "relatively" cool airmass in place across the CWA. The frontal boundary may waffle north into southern Georgetown and Williamsburg counties this evening and overnight, which would have implications the diurnal curve in that area. Otherwise, moisture will begin to overspread the surface wedge this evening, with potential for light showers increasing from west to east, beginning 02-03Z. Precip will be weakly forced, and latest HRRR suggests a possible lull in activity Friday after 12-13Z, before additional overrunning showers start spreading in from the west after 20Z. Will also note that long period (15 sec) swells arrive north of Cape Fear just after 12Z Friday, and spread to the NE SC coast during the afternoon. This will produce rough surf, particularly north of Cape Fear, with some 5 ft breaking waves. Criteria for a High Surf Advisory is 6 ft breakers, and we will be on the cusp along the beaches of New Hanover and Pender counties. Lows tonight generally within a degree or two of 50 north, to mid 50s south, with the caveat that warmer air could slip northward into southern Georgetown and Williamsburg counties at some point. Highs Friday will remain a tad on the cool side of climo, ranging from upper 50s inland to around 60 southern and eastern sections, under mostly cloudy skies and the influence of scattered light showers. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... Forecast confidence is moderate to high this period. Inland high pressure at the surface centered north of the area will prevail through the period while some upper disturbances move through the generally zonal flow aloft. Some light rain will be possible Friday night into early Saturday with a bit better chances/amounts Sunday, possibly starting late Saturday night and even lasting into early Sunday night. High temperatures should stay below normal while low temps stay above normal. && .LONG TERM /MONDAY THROUGH THURSDAY/... Forecast confidence is moderate to high through Tuesday night, then low to moderate thereafter. The period should start off dry with high pressure prevailing, except for a few lingering light showers in SC early Monday. The next rain chances could come as early as Wednesday across inland areas as deeper moisture begins to encroach on the area ahead of the next storm system, although it appears the best chances should be Wednesday night into Thursday as a potent storm system likely impacts the area. Some locations could pick up an inch or more. Also will need to monitor for a low-end severe storm risk given the likely high shear/low instability setup. Temperatures should be near to below normal until Wednesday night with the coldest night being Monday night when some of the normally colder inland locales possibly get to near freezing. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Ceilings MVFR to start out the period with showers expected to move in at KFLO/KLBT from the west around 05Z. IFR is expected for KFLO but confidence was lower for the NC sites so decided to keep MVFR conditions for KLBT at this time. IFR ceilings could be possible and conditions will continue to be monitored as this cloud deck moves in. For KMYR/KCRE, IFR ceilings and precip are looking to arrive closer to 10Z. MVFR is then expected to persist into Friday morning. Extended Outlook...Moderate confidence Fri night through Tue. Restrictions mostly from low clouds Fri night (possibly into early Sat), especially SC terminals. The risk of restrictions increases Sat night into maybe early Mon due to low clouds and some rain. VFR should then return through Tue. && .MARINE... Through Friday: Surface front was laying just south of the South Santee this afternoon and is expected to remain quasi-stationary through Friday. The result will be continued NE flow across the waters through the period. The gradient will tighten up overnight with surface pressure rises across the interior Carolinas, and winds will surge as a result. A Small Craft Advisory will be raised with this forecast package, as mixing should produce gusts of 20 to 25 knots after 09Z. Winds will begin to diminish after 15Z Friday, but seas will stay up through the day, as NE wind waves blend in with a long period (up to 15 sec) E swell. Friday night through Tuesday: Confidence is moderate through the period. High pressure to the north should prevail most of the period keeping winds mainly from the north/northeast 20 kt or less. Small Craft Advisory conditions likely into early Saturday for at least part of the area, mainly due to moderate swells from a distant Atlantic low. SCA conditions could return Monday/Tuesday, at least for the SC waters. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 1 AM Friday to 1 PM EST Saturday for AMZ250-252-254-256. && $$ SYNOPSIS...ILM UPDATE...LEW NEAR TERM...CRM SHORT TERM...RJB LONG TERM...RJB AVIATION...LEW MARINE...SHK/CRM
Area Forecast Discussion
National Weather Service Indianapolis IN
931 PM EST Thu Dec 8 2022 .Forecast Update... Issued at 929 PM EST Thu Dec 8 2022 Surface analysis this evening shows high pressure in place over Ontario, allowing a cool easterly surface flow across Central Indiana. Low pressure was found over NB, along with an associated warm front that stretched across MO. Radar mosaics show an area of associated precipitation over IA as earlier rain over Central Indiana has exited to the east. GOES16 continues to show abundant cloud cover across Central Indiana as the cool dirty easterly flow continues. Temperatures remained in the lower 40s and dew point depressions remained low. This will be favorable for continued cloud cover and patchy fog as we have seen the past several nights. Models fail to show much in the way of forcing aloft overnight as the warm front and associated low is expected to approach on for Friday. Forecast soundings and time heights show continued lower level moisture through the night. Models do hint at some moisture pushing into western Central Indiana after 10Z…but given radar trends and the progression of the low, better forcing should arrive after 12Z Fri. Thus will keep the forecast mainly dry tonight with lows mainly around 40. && .Short Term...(This evening through Friday) Issued at 255 PM EST Thu Dec 8 2022 The widespread light rain, with the back edge lined up back to the Ozarks per radar mosaic, will continue to move over areas south of I- 70 into the evening. The rain was associated with isentropic lift to the north of a Tennessee Valley quasi-stationary front and impulses in fast southwest flow aloft. The somewhat heavier rain was limited to areas south of the Ohio River associated with moisture convergence closer to the stalled, northward sloping front. This should remain the case through the evening. Isentropic support will be ending early and lead to short mostly dry period overnight save perhaps some patchy drizzle. That said, moisture will be plentiful under a steep inversion which will lead to some more patchy fog and low stratus overnight. Then, an upper low will track from Nebraska to Iowa tonight and Lake Michigan late Friday. Meanwhile, an occluded frontal system associated with the upper low will move across central Indiana on Friday and bring more rain to mainly northern sections Friday. 125+ knot jet streaks may also contribute to a few heavier pockets of rain. Went likely PoPs north of I-70 with chance Pops over southern sections. Combo of synoptic lift and moisture will keep the clouds around and limit diurnal temperature curve with overnight lows tonight in the upper 30s to middle 40s tonight and afternoon highs Friday in the middle 40s north to middle 50s south. && .Long Term...(Friday night through Thursday) Issued at 255 PM EST Thu Dec 8 2022 Extended periods synoptic overview... Pattern adjustments appear to be the general theme for the extended periods, kicking off Friday night as some mid-lvl height rises are progged to arrive for the Mid-Missouri Valley. Items worth taking notes on will be a beefy lobe of vorticity progged to dig south of the Pac-NW Saturday, which will help to create greater longwave volatility in the later periods or more specifically Tuesday into Wednesday. As the aforementioned trough gets its act together and begins to drift east, the response from the downstream wave will be modest return flow from GOMEX. Once this system arrives in the Ohio Valley sometime mid/late next week, the cold conveyor appears to become active with a northwest flow. Friday night through Sunday... Guidance has been relatively consistent with height rises for the Ohio Valley Fri ngt in the wake of a weak mid-lvl shortwave lifting into Ontario. Ensembles have been indicating some anti-cyclonic flow in the lower levels, which should assist with providing a period or two of benign weather Saturday; however, as noted earlier with the volatility within the longwave pattern, there is still a quasi-zonal orientation to the upper level flow. This is supportive in what some of the operational solutions are indicating, with precip chances quickly returning Saturday evening. The caveat will be how quickly the lower levels can moisten backup, given the lack of omega and a conveyor to bring ascending parcels to help kick-off the precip. There will be stronger ascent to parcels further south across KY/TN perhaps southern IN, but confidence just isn`t there to bring higher POPs further north at this time. This could easily be one of those setups where clouds return from a weak southeasterly low-level flow and provide a thick stratus shield inhibiting the surface from warming. Weak boundary pushes east across the region Sat eve, with some weak cold air advection returning from the leading edge of an elongated surface ridge. This could be setting the stage for trapped low-level stratus early Sun, but more likely late Sun into Mon morning. Think an ideal inversion setup in this case, which could allow for a foggy start to next week given the lack of a gradient in the lowest levels and also minimal mixing to scour out the trapped stratus layer. Monday through Tuesday... A few days ago the focus was turning towards Tue, and while that still appears to be an interesting setup, its the setup prior that will dictate how the later periods will unfold. Ensembles membership has continued to highlight with minimal spread/noise in a robust trough beginning to pivot east through the Southern Rockies Mon aftn/eve. This will result in downstream strong meridional flow from the Western GOMEX pointing due north through ArkLaTex into the Missouri Valley Mon ngt. This strong ascent to parcels coupled with contrasting airmasses set the stage for a very dynamical setup for Tue/Wed periods. Quick amplification to heights across the Ohio Valley has been a trending feature Tue, as the downstream shortwave over Eastern Quebec likely slows the forward progression the next system. Thus leading a nudge towards Tue ngt/Wed as the more favored timing for the possible convection/heavy rainfall concerns. Wednesday through Thursday... Well developed shortwave continues to be the main focus for Wed somewhere east of the Rockies. There is some uncertainty with respect to the placement, given the equally robust downstream wave exiting the Northeast CONUS. Considerable instability still appears to be the main course, but placement/timing is still the elusive element. We are still somewhat confident that convection and heavy rainfall are possible given the current track of a surface feature displaced to the northwest of Central Indiana. This does appear to be a consistent feature, thanks to the slower evolution and arrival. Confidence in heavy rainfall Wednesday...medium. && .Aviation...(00Z TAF Issuance) Issued at 555 PM EST Thu Dec 8 2022 Impacts: - MVFR or worse conditions are expected for much of the TAF period. Discussion: A wave of precipitation was exiting central Indiana early this evening. This will bring a brief break of precipitation as a frontal boundary continues to linger south of Indiana. Extensive lower level moisture is expected to persist overnight along with light northeast surface flow ahead of the approaching low. This will lead to ongoing MVFR cigs and visibilities this evening and overnight. An area of low pressure is expected to push across Central Indiana on Friday, led by a warm front pushing across the state by late morning and early afternoon. HRRR shows an associated band of showers expected to push across the TAF sites. As this passes continued MVFR or worse conditions will be expected. Forecast soundings continue to suggest abundant lower level moisture as these features pass. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...Puma Short Term...MK Long Term...Beach Aviation...Puma
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
741 PM PST Thu Dec 8 2022 .SYNOPSIS...08/145 PM. A weak weather system will bring light showers to the Central Coast tonight into very early Friday. Then a stronger system will bring periods of heavy precipitation to all areas Saturday afternoon through Sunday night. Lingering showers are possible Monday, otherwise a drying trend with below normal temperatures is expected through the middle of next week. && .SHORT TERM (THU-SUN)...08/740 PM. ***UPDATE*** Another benign weather day today with partly cloudy skies. Max temps across csts/vlys again came in within 2 degrees of 60 today or 5 to 10 degrees blo normal. The latest NAM and HRRR are downplaying the tonight`s trof even more than the earlier runs and its doubtful that SLO county will see anything more than a sprinkles. 00Z does not deviate much at all from 12Z runs and all systems are green and go for a moderate rain event over the weekend. Will issue a forecast update to reduce SLO county POPs tonight and Friday morning. ***From Previous Discussion*** A weakening cold front is just offshore and will be moving inland tonight. Hi res models continue to show further weakening overnight with only a very light amount of rain at best and generally just across the northwest portion of SLO County. Elsewhere, just an increase in clouds but no rain. The remainder of Friday will be quiet with a few clouds but also plenty of sunshine. Temps will continue to be on the cool side with highs 4-8 degrees below normal. The fun begins Saturday as a cold 522dam upper low drops out of the Gulf of Alaska. Models have been speeding up the arrival of pre-frontal showers the last few runs and there could be rain reaching the Central Coast as early as sunrise Saturday and into LA County by noon Saturday. As the low and associated cold front continues to march southeast towards California later in the afternoon, southerly winds will start increasing and good diffluence aloft will generate strong upward motion, which in turn will increase rain rates. That combined with 850mb southwest winds of 50kt generating additional orographic enhancement near the coastal mountains will push rain rates up to at least a half inch per hour and locally higher. The peak of the storm still appears to be during the overnight hours Saturday night into Sunday morning when the best low level forcing and jet dynamics come together. Models are still showing a fairly rapid movement through the area so the period of heaviest rain should be limited to a 3 to 6 hour period in any one area. By Sunday morning the steady rain should be through LA County with still a fair amount of shower activity behind it. While the air mass isn`t particularly unstable an isolated thunderstorm or two can`t be ruled out. So while rain rates will be quite high during the peak of the event, no significant flooding or debris flows are expected. Showers will continue behind the front but will be decreasing with time Sunday into Sunday night. As is typical with strong low level jet scenarios like this snow levels will jump quite a bit as the heavy precip approaches. Latest models are showing snow levels between above 7500 feet for a large portion of this event, meaning significant snow accumulations will be confined to very high elevations. Snow levels will lower rapidly Sunday into Sunday night but showers will be short lived with minimal impacts at that point. One exception may be the Grapevine on Interstate 5 where by late Sunday night there is a chance of light accumulating snow at pass level which could lead to travel delays. Southerly winds will be picking up quickly Saturday ahead of the front and advisory level winds are likely across interior SLO County, the Antelope Valley, and the mountains. It will be breezy across the coast and valleys as well but likely below advisory levels. .LONG TERM (MON-THU)...08/141 PM. The upper low will be over the northern San Joaquin Valley Monday with still ample moisture and forcing over southern California to squeeze out scattered showers just about anywhere. At the very least it will be a cool day with highs mostly in the 50s at lower elevations and 20s and 30s in the mountains. Dry weather expected Tuesday through Thursday with slowly warming temps, but still generally below normal through the period. Overnight lows will likely drop to near or below freezing in many valleys and even some coastal areas. && .AVIATION...08/2315Z. At 23Z at KLAX, there was no marine layer or marine inversion. 60 percent chance of LIFR conditions at KPRB by 10-15Z Fri. Light -SHRA with MVFR ceilings possible 12-18Z Fri at KPRB KSBP (30%), and KSMX (20%). SCT015-25 likely at all other sites 12-18Z Fri, but without an inversion the chance of ceilings is only 20-30%. High confidence in generally light winds. KLAX...Moderate confidence in VFR through Friday, except for a 30% chance of MVFR ceilings 12-18Z. Lighter than usual winds expected, with high confidence in NO significant east winds. KBUR...Moderate confidence in VFR through Friday, except for a 30% chance of MVFR ceilings 12-18Z. Lighter than usual winds expected. && .MARINE...08/643 PM. For the Outer Waters, moderate to high confidence in current forecast. Tonight through Friday afternoon, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. For Friday night and Saturday, high confidence in southerly winds increasing to SCA levels as well as seas with a 60-70% chance of Gale force winds developing Saturday afternoon across PZZ670/673. The strong southerly winds will continue Saturday, before shifting to the west and northwest on Sunday with SCA level winds/seas continuing. For Monday and Tuesday, seas will gradually diminish below SCA levels, but there will remain a 50% chance of SCA level winds. For the Inner Waters north of Point Sal, moderate to high confidence in current forecast. Tonight through Friday night, high confidence in winds and seas remaining below SCA levels. On Saturday and Saturday night, high confidence in SCA level southerly winds and seas with a 50-60% chance of Gale force winds. On Sunday, high confidence in SCA-level westerly winds and seas. For Monday and Tuesday, high confidence in winds and seas remaining below SCA levels. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Tonight through Saturday afternoon, high confidence in winds and seas remaining below SCA levels. For Saturday afternoon and night, high confidence in SCA level southerly winds with a 40% chance of SCA level seas. On Sunday, winds will shift to a westerly direction with high confidence in continued SCA level speeds and the 40% chance of SCA level seas. On Monday and Tuesday, high confidence in winds and seas remaining below SCA levels. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Gale Watch in effect from Saturday afternoon through Saturday evening for zones 645-670. (See LAXMWWLOX). && $$ PUBLIC...MW/Rorke AVIATION...Kittell MARINE...RAT SYNOPSIS...MW Experimental Graphical Hazardous Weather Outlook at:
Area Forecast Discussion
National Weather Service Lubbock TX
527 PM CST Thu Dec 8 2022 ...New AVIATION... .SHORT TERM... (This evening through Friday) Issued at 220 PM CST Thu Dec 8 2022 Early afternoon surface analysis showed a surface cyclone moving east across the Oklahoma Panhandle, bringing breezy westerly winds to the CWA this afternoon. These downslope winds will result in drying and warming over the region through today. Temperatures are still on track for highs in the 60s on the Caprock and low-70s off the Caprock. Upper-level water vapor imagery and RAP analysis showed a shortwave trough moving across the Intermountain West. A weak "cold" front is expected to push through the region late this evening, mainly bringing slightly drier surface conditions to the area. However, a surface cyclone is expected to form over southeastern Colorado, resulting in moisture being advected into the CWA through the night, helping to increase precipitable water values to near the daily max for the area once again. This could result in patchy fog over parts of the Rolling Plains early tomorrow morning. As the aforementioned upper trough moves into the Plains, moist isentropic ascent is expected to increase over our region, bringing the potential for light rain over the forecast area tomorrow afternoon through the evening. GKendrick && .LONG TERM... (Friday night through next Wednesday) Issued at 220 PM CST Thu Dec 8 2022 The next shortwave expected to impact the area tomorrow night can already be seen on mid-level water vapor analysis entering the Pacific Northwest. With a surface high over the GoM, south southeasterly winds will give way to low level moisture advection across Texas. Weak lift ahead of the shortwave, along with a narrow window of Pacific moisture will lead to the continued chance for some rain showers across portions of the Rolling Plains and southeast Panhandle into the evening hours tomorrow. However, there is a dry layer around 700-600mb, which will keep any precipitation light in nature with mostly light amounts of accumulation expected. With the abundance of low level moisture tomorrow night, a low deck of stratus is expected to persist through the night before clearing out from northwest to southeast following a weak frontal passage Saturday morning. A few additional showers may linger across the southern Rolling Plains Saturday morning before the dry air behind the front filters in across the forecast area. Another weak and dry shortwave will follow in behind the previous on Saturday into Saturday night, with little to no affect to the forecast. Therefore temperatures are actually expected to warm slightly through the weekend and into Monday with highs approaching the lower 70s off the Caprock. The next system will creep into northern Cali Sunday with surface troughing developing leeward of the Rockies and breezy southwest winds returning to West Texas. By Monday, the upper closed low will be entering the Great Basin region with the lee trough deepening into a surface low over eastern Colorado. A tightening of pressure gradients across the area combined with daytime heating and momentum transfer of 40 knot 700mb winds to the surface will allude to breezy to windy conditions Monday. In addition, there is a slight chance for rain showers to return across the southeast Panhandle and Rolling Plains Monday with southerly surface winds pulling in Gulf moisture across much of eastern and central Texas combined with isentropic lift ahead of the upper low. Winds will remain breezy overnight with the approaching system, along with the deepening surface low in the Central Plains. By Tuesday morning the Pacific front will move through with windy west surface winds expected throughout the day with the passing upper low to the north and 100 knot 500mb jet axis overhead. Some model discrepancies still exist on the exact location of the passing jet axis, but overall the trend is windy conditions following the Pacific front Tuesday. Cooler air will begin to also filter in Tuesday with highs in the 40s along the Caprock and 50s off the Caprock. The cold front is then expected Wednesday with an additional surge of cool Canadian air in the 40s and lower 50s across the area. In addition to cooler highs, overnight temperatures by the middle of next week will dip into the 20s. With breezy overnight winds, morning wind chills may also be in the single digits to teens across portions of the area. && .AVIATION... (00Z TAFS) Issued at 520 PM CST Thu Dec 8 2022 VFR through the night will give way to MVFR CIGs by morning as deeper moisture spreads W-NW across the terminals. CDS should see a brief bout of IFR CIGs and maybe some fog toward daybreak before widespread MVFR decks arrive later in the morning. Some SHRA are likely at times from LBB-PVW by the afternoon. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...10 LONG TERM....11 AVIATION...93