Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/19

Area Forecast Discussion
National Weather Service La Crosse WI
550 PM CST Sat Nov 30 2019 .SHORT TERM...(This Evening through Sunday Night) Issued at 231 PM CST Sat Nov 30 2019 Quite the weather system across the region at the moment, with an impressive closed/stacked low and mid level circulation meandering slowly east through Nebraska. That feature is expected to continue an eastward jaunt the next 24 hours, eventually ending up over the lower Great Lakes by midday Sunday, continuing to impact our region with a myriad of weather conditions. First up, quite the PV advection streamer ahead of the upper low continues to blossom an axis of more widespread precipitation, in the wake of an earlier return to mainly drizzle. Some thunder is occurring as that band sweeps northeastward across the area with MUCAPE values spiking to a rather impressive 200-500 J/kg (highest east of the Mississippi River), with precipitation type a little tricky owing to an initial loss of ice/warm nose aloft south of I-94 but additional lift from any convective processes likely enough to briefly overcome that warming and give more of a rain/snow/sleet setup. Farther north is where the most concern lies (mainly Clark/Taylor counties in our area) where strong lift and dynamic cooling north of the upper low looks to result in mainly snow, with a few hour period of heavy snow very much possible in that convective band. Going forecast snow amounts already has this idea messaged well, with not too many changes foreseen, save for raising amounts across Clark County per near-term guidance trends, where will upgrade the advisory to a warning. Otherwise, looking like we will again lose the deeper moisture into this evening as pronounced dry slotting arrives, even up to and north of the I-94 corridor, suggesting a return to light precip/drizzle is most likely at times for a few hours. Things change again quickly after 02Z (per current trends) with a tightening of the low/mid level temperature gradient north of the low, with a subsequent uptick in 900-600mb frontogenetical forcing, particularly near and north of I-90. That should help force redevelopment of additional precipitation (tricky type initially closer to I-90 given residual warm nose/loss of ice), with deformation forcing kicking into gear late tonight into Sunday driving a final axis of precipitation back south through the area before ending Sunday evening. As alluded to above, overall precipitation type(s) are somewhat of a disaster to forecast through tonight given loss of ice at times and periods of a more enhanced warm nose, particularly through this evening. However, one bonus is that surface temperatures across much of the area south of I-94 have warmed above freezing, helping mitigate any freezing rain risk. Additionally, areas north of Interstate 94 do look to remain primarily snow with plentiful ice nuclei and any warm nose 1C or less, with 4 to 8+ inches of additional accumulation expected, pending exactly where the axis of heaviest precipitation "pivots" tonight. Farther south, we should eventually erode the warm nose late tonight into Sunday, with precipitation becoming all snow before ending. Envision a swath of 1 to 3 inches generally near/north of I-90 and south of I-94 during the late night and into Sunday, perhaps locally higher should any bands line up over the same areas for longer, with less than an inch farther south as forcing wanes quickly into the afternoon. As for headlines, will tack on Clark County, WI to the warning, while also re-issuing an advisory for Monroe, Juneau, and Adams Counties where the heavier snow band may pivot later tonight. May eventually need to add additional counties farther west along I-90 with the potential for sloppy end of weekend/holiday travel into tomorrow, but will allow later shifts to assess that need. .LONG TERM...(Monday through Saturday) Issued at 231 PM CST Sat Nov 30 2019 Quiet weather expected for the work week with seasonable temperatures for early December. The region is mainly under Pacific- influenced zonal to slightly northwest flow aloft with periodic ridges and troughs crossing the region over the course of the week. Low chances for snow return near the end of the period for northern Wisconsin, but confidence in any details out that far remains low. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 550 PM CST Sat Nov 30 2019 RAP soundings continue to show that there will be no ice seeding from aloft through much of the night, therefore, the surface temperature will be the primary driver of the precipitation type at the surface. Meanwhile aloft planes will have to deal with icing. As the case through the afternoon, there may be brief periods of ice pellets with any convection. In addition, there may be some thunder along the wave lifting out of central Iowa. However, there are some question in the RAP/HRRR whether it will even get into the TAF sites. Late tonight and Sunday morning, ice aloft returns with the deformation band. This is when the snow will return. Snow at the TAF sites will likely range between 1 and 3 inches. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory from midnight tonight to 6 PM CST Sunday for WIZ042>044. Winter Weather Advisory until 6 PM CST Sunday for WIZ032>034. Winter Storm Warning until noon CST Sunday for WIZ017-029. MN...Winter Weather Advisory until 6 PM CST Sunday for MNZ079. IA...None. && $$ SHORT TERM...Lawrence LONG TERM...Peters AVIATION...Boyne
Area Forecast Discussion
National Weather Service Cheyenne WY
756 PM MST Sat Nov 30 2019 .UPDATE... Issued at 749 PM MST Sat Nov 30 2019 Strong winter storm finally beginning to push east of the area with slowly improving conditions this evening. Decided to cancel most of the High Wind Warning and replace it with Winter Weather Advisories since blowing snow is becoming the main hazard. Kept the Blizzard warning going for far eastern Wyoming and the northern/central Nebraska panhandle. Webcams, observations, and a few spotters are still reporting blizzard conditions with blowing snow and quarter mile or near quarter mile visibilities. Will give this a few more hours and then consider downgrading to an Advisory for blowing snow since the falling snow associated with the storm has pretty much ended for the night. Otherwise, kept the Blizzard Warning going for the wind prone areas that are still receiving observing very low visibilities in blowing snow with winds over 60 mph. UPDATE Issued at 439 PM MST Sat Nov 30 2019 ...Please see latest 0Z aviation discussion... && .SHORT TERM...(This evening through Sunday) Issued at 245 PM MST Sat Nov 30 2019 ...POWERFUL WINTER STORM CONTINUES TO BRING BLIZZARD CONDITIONS TO WESTERN AND NORTHERN PORTIONS OF THE CWA INTO TONIGHT... Recent WV imagery and RAP analysis show the deep upper level low continuing to push east over north-central Nebraska with a 988 mb sfc low per mesoanalysis. This surface low will continue to provide moisture to portions of the CWA before pulling off farther east. Strong pressure gradients are present along with 60-70 kt flow aloft from 800-700 mb resulting in strong winds and widespread blowing snow across Southeast Wyoming and Western Nebraska. Wind gusts observations along I-80 between Cheyenne and Laramie have consistently been in the 55 to 70 MPH range all day. Additionally, received numerous reports of power line damage in the Nebraska Panhandle from strong winds. Blizzard conditions began developing across the South Laramie Range and South Laramie Range Foothills in Wyoming in addition to Banner County in Nebraska. These zones were upgraded to Blizzard Warnings with the morning update and have since met the 3 hour criteria. WYDOT and NEDOT webcams have shown whiteout conditions with snow drifts across many roadways. Other zones within the High Wind Warning have seen significant blowing snow at times as well. Falling snow seems to be wrapping up with the exception being the eastern most counties in the CWA. Recent radar reflectivity shows returns south of the Black Hills through Chadron where snow reports of 1 foot were received this morning. Other sites farther south through the Panhandle are still reporting snow where radar is most likely overshooting bands of snow. An additional 1 to 3 inches may fall in these eastern zones. As snowbands continue to push east this evening, stronger winds will move in over fresh snowfall which will result in additional blowing snow over the NE Panhandle. Winds will begin to decrease this evening, but will still remain elevated into early Sunday morning as 50 kt winds aloft will remain in place until then. The current Winter Storm and High Wind Headlines continue through 5 AM MST Sunday. Hazardous travel will continue through the night as slick/snow covered roads, reduced visibility in blowing snow, and strong winds continue. .LONG TERM...(Sunday night through Saturday) Issued at 245 PM MST Sat Nov 30 2019 Upper level ridging will slide in in the wake of the strong sfc low that that has brought snow/blowing snow and strong winds across the CWA. Temperatures will begin to warm back to near normal in the low 40s east of the Laramie Range and 30s west starting Monday with mostly dry weather. Breezy winds will also return Monday with an approaching shortwave and tightening gradients. WRKBRX is around 50% with 50-60 kt westerlies at 700-800 mb. A cold front will move in from the northwest Monday night which will bring the chance for snow across the higher elevations, but only light accumulations expected at this time. Afterward, zonal flow aloft takes over as a progressive shortwave moves through the southern Rockies Thursday. Recent model guidance has shifted this shortwave south so chances of precipitation with this system seem unlikely. Looking towards week`s end, models hint at our next large scale disturbance making its way into the Pacific Coast, but plenty of model uncertainty with strength and timing of the trough are present. 12z GFS currently pushes this disturbance through relatively quickly while the 00z Euro digs the trough farther south, potentially too far south for any precipitation over our CWA. CPC`s 6-10 day outlook suggests above normal temperatures and above normal precipitation heading into next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 439 PM MST Sat Nov 30 2019 While ceilings across southeast Wyoming and the Nebraska Panhandle are improving, visibility continues to be impacted by blowing snow. Categories are down IFR and LIFR. Visibility will gradually improve overnight west to east as high winds taper off. Flight conditions will be much more favorable tomorrow especially after 18Z. && .FIRE WEATHER... Issued at 314 AM MST Sat Nov 30 2019 No fire weather concerns w/ deep snow pack already in place over a large part of the area. Widespread snow & strong winds, along with areas of blizzard conditions can be expected over the next 12 hrs. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Blizzard Warning until 5 AM MST Sunday for WYZ102-108-110-116- 117. Winter Weather Advisory until 5 AM MST Sunday for WYZ101-106-107- 118-119. High Wind Warning until 5 AM MST Sunday for WYZ106. NE...Blizzard Warning until 5 AM MST Sunday for NEZ002-003-019-020- 095-096. Winter Weather Advisory until 5 AM MST Sunday for NEZ021-054-055. && $$ UPDATE...TJT SHORT TERM...MB LONG TERM...MB AVIATION...CW FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1003 PM EST Sat Nov 30 2019 .UPDATE... The first phase of mid level isentropic ascent produced a couple rounds of radar returns across the Saginaw valley and Thumb during the early to mid evening. The forcing and moisture supply slightly overachieved compared to the newest model data and was still barely able to reach the surface with some trace amounts of rainfall. However, given the added moisture aloft, substantial erosion of the low level dry air is occuring as suggested by the DTX 00Z sounding. The sounding also shows elevated warm air solidly established in the 850 to 700 mb layer and reaching near +6 C at about 800 mb. Granted there remains some wet bulb cooling that takes place as the first round of significant moisture arrives but cross sections of RAP data indicate the warm nose surging well north into the Saginaw valley prior to sunrise at about +3 C to ensure complete melting of hydrometeors. Freezing rain then remains the expected precipitation type primarily along and north of the I-69 corridor with some leakage south into northern Livingston, northern Oakland higher terrain, and northern Macomb counties, although brief in these areas. Wet bulb cooling potential is shown in late evening observations across the area along with cold and dry air advection from southern Ontario. Expect surface temperatures to settle into the 30-32 F range resulting in high end advisory icing assuming no increase in liquid QPF that averages 0.25 to 0.5 inch during the night. The QPF seems reasonable based on plentiful coverage of convection indicated upstream along with more than a handful of lightning strikes. Some questions remain on additional precipitation type transitions for the second surge of moisture set to peak during the morning hours after sunrise. Forcing during this phase of the event is driven by strong deformation within a large/high amplitude trowal that has all the elements of outstanding vertical motion response. The occlusion process appears to quickly displace the mid level warm nose eastward resulting in a thermal profile supporting a change to snow around or shortly after sunrise most likely along and north of M-46. The 00Z runs of the NAM and RAP both offer additional QPF in the 0.25 to 0.5 inch range in the 12-18Z time period. This is likely a reflection of the strong vertical motion response in convective instability on the south flank of the trowal axis. Moisture availability is already well established leaving uncertainty due to the actual position and residence time of the precipitation axis. That being said, it is possible higher additional snow accumulation could occur after sunrise on top of any icing prior to sunrise which together could require a headline upgrade for the Tri Cities and northern Thumb in upcoming forecast updates. && .PREV DISCUSSION... Issued at 708 PM EST Sat Nov 30 2019 AVIATION... A large low pressure system over the Plains moves into the Midwest tonight presenting a wide range of aviation weather challenges for SE Michigan tonight through Sunday. The first is ceiling trends during the evening as strengthening easterly low level wind attempts to erode stratus across the terminal corridor. The incoming dry air also affects the onset of higher precipitation rate set to begin mainly after midnight with some trace amounts possible during the evening. Once underway, precipitation type ranges from all rain in the DTW area to a wintry mix of freezing rain, sleet, and snow in the FNT to MBS area. Increased precipitation rate and the approach of the associated warm front lead a downward trend in ceiling and visibility with IFR entrenched across the region by sunrise. Gusty east wind tonight diminishes and becomes variable in direction Sunday morning as the surface low slides across southern Lower Michigan. The track of the system also leads to a decrease in precipitation from south to north during the morning while borderline IFR/LIFR with drizzle and fog holds along and north of the surface low. The DTW corridor likely breaks out into low end VFR in SW flow Sunday afternoon. For DTW... Breaks in low cloud coverage lead to fluctuation between VFR and MVFR during the evening on a gusty east wind. Surface temperature remains in the mid to upper 30s resulting in just rain as coverage and intensity increase after midnight. The approach of the low pressure system and leading pattern of rain both work to return flight conditions to IFR by sunrise through Sunday morning. DTW THRESHOLD PROBABILITIES... * High for ceiling at or below 5000 feet tonight through Sunday. * High for rain as precipitation type tonight and Sunday. * Low for thunderstorms late tonight. PREV DISCUSSION... Issued at 340 PM EST Sat Nov 30 2019 DISCUSSION... Occluding vertically stacked mid latitude cyclone centered over eastern Nebraska late this afternoon will steadily eject east- southeast over the next 36 hours, arriving at the MI/OH border region by Sunday evening. Blossoming corridor of mid level warm air advection tied to increasing southerly flow along the downstream flank of this system will lift into lower Michigan tonight. Meaningful saturation tied to early stages of the corresponding isentropic lift met with some resistance locally through the evening period, the resident dry profile held within easterly flow continuing to define conditions outside of perhaps a few pockets of light radar returns. Surface temperatures easing down into the lower and middle 30s through this time. A pronounced period of mid level forcing will emerge during the early-mid morning hours, driven by favorable upper jet dynamics and strengthening deformation engaging the inbound elevated warm frontal slope. This will translate into a period of widespread precipitation during this time. Diminishing deep layer stability given the dynamics and high theta-e content will offer some heavier convective bursts/possible thunder. Precipitation type ultimately defined by both magnitude and northward expanse of the elevated warm nose, working across a surface temperature that remains tenuously near or just below freezing. The advective process expected to sufficiently overwhelm the column for areas generally along/south of the M-59, so any light wintry mix will be brief and confined to the early stages as saturation/wet bulbing commences. A surface temperature still in the vicinity of freezing will offer a several hour window for freezing rain across the I-69 corridor (and perhaps far northern Oakland/Macomb counties), before temperatures nudge above 32F. Precipitation type transition and ice/snow accumulation potential remains more complex across the Saginaw valley and northern thumb region. An unsurprising mixed model signal on precipitation type residence time over this corridor, owing to differences in the strength of the warm nose at this latitude and influences of higher precipitation rates on this warm layer. Meaningful precipitation rates likely remain below 6 hours in duration, while a mixed phase scenario places an additional ceiling on possible snow/ice accumulation. Ice accretion efficiency will be aided by a firm southeast wind gusting up to 30-35 mph, but perhaps muted too some degree by marginal temperatures still in the 30 to 32 degree range. This lends more confidence in witnessing advisory levels conditions over this corridor. Steady decline in precipitation coverage from southwest to northeast through late morning as the cold frontal occlusion pivots through and the attendant mid level dry slot takes residence. Substantial component of low level moisture left behind ensures a cloudy and dreary day. Some additional pockets of light rain or drizzle a possibility as low level convergence increases beneath the mid level cyclonic flow, but greater ascent currently projected to develop across the Ohio valley during the latter half of the day. Broader distribution in highs Sunday - mid 40s south to mid 30s north. Low level flow backs to northerly upon the eastward exit of the upper low, allowing colder air to funnel back in Sunday night. Stretch of dry and cooler conditions will define the early week period. Low stratus likely holds firm Monday within residual low level thermal troughing. Any clearing as warm air advection commences Monday night will then be replaced by thicker high cloud Tuesday in advance of an inbound weak northern stream wave. This wave will glance across the northern great lakes Tuesday night and Wednesday. Moisture content will be lacking with this system, so simply a low end potential for light snow/flurries mainly north during this time. MARINE... With a slight southward deviation in the track from yesterday`s forecast, stronger winds are a much higher possibility for southern Lake Huron with gale force gusts likely tonight. Gale force gusts still remain likely in northern and central Lake Huron with a period of time Sunday morning of sustained gales possible. This increase in wind strength is also due to the track change as north/central Huron will remain in the cold sector of the storm creating a longer duration unstable thermal profile. For the nearshore zones, gales are likely for the Thumb and Saginaw Bay through the night. Waves will remain elevated above small craft advisory thresholds through Sunday, possibly into Monday. For Lakes St. Clair and Erie, there could be a brief window of gale force gusts late tonight into early Sunday morning. Waves will quickly respond in those lakes with the east wind late this evening leading to the small craft advisory starting at 3Z. HYDROLOGY... An area of precipitation will lift across southeast Michigan tonight. The heaviest precipitation will occur during the early and mid morning hours Sunday. A bulk of the precipitation will fall as rain south of the I-69 corridor with a mix of snow, sleet, freezing rain and rain further north. Precipitation will then taper off Sunday morning as the system crosses the area. Total rainfall will generally range between one half and three quarters of an inch. Ponding of water in low-lying areas and rises on area rivers is expected. However, widespread flooding is unlikely given the higher permeability of upper layer soils which still have yet to freeze. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 10 AM EST Sunday for MIZ047>049- 053>055-060>063. Lakeshore Flood Advisory until noon EST Sunday for MIZ049-055-063. Lakeshore Flood Advisory until 7 AM EST Monday for MIZ048. Lake Huron...Gale Warning until 10 AM EST Sunday for LHZ421-422-441>443-462>464. Gale Warning until 10 PM EST Sunday for LHZ361>363. Lake St Clair...Small Craft Advisory until 10 AM EST Sunday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory until 10 AM EST Sunday for LEZ444. && $$ UPDATE.......BT AVIATION.....BT DISCUSSION...MR MARINE.......KDK HYDROLOGY....MR You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion...Updated
National Weather Service Peachtree City GA
1000 PM EST Sat Nov 30 2019 .Update... No changes planned for the forecast. Rain and a few thunderstorms will gradually spread east and south across the area. There has been a general weakening trend to the thunderstorms as they move east. 41 .Previous... .SHORT TERM /Tonight through Sunday Night/... Main concern is the potential for strong/severe storms in NW and WC GA after 9 PM tonight. Low level moisture increasing from the west across AL today and faster than indicated by recent HRRR runs, though there is substantial dry air over eastcentral GA. Concerned that instability will be a tad higher than forecast. With HREF mean 0-1km SRH progged over 400 m2/s2 will be sufficient for a brief tornado or two. Some HREF members also hinting that activity could sneak into NW corner by 8 PM but more likely from 9 PM-midnight. As line of convection spreads east, strong winds still possible it should weaken as large scale forcing and environment (mainly instability) become less favorable. Will likely see little or no CG lightning except for a few strong cells before 3 AM. Line will move through steadily and should be clear of the CWA by noon Sunday with strong and gusty west winds. Could be close to advisory criteria, but initial indications are it will remain below criteria. As second shortwave dives into TN valley Sunday night, could see some snow showers produce very light accumulations in elevations above 2000ft. Surface temps have come in a bit colder than previous guidance so have a little more snow showers than this time yesterday. Accumulations will mainly be in grassy areas and less than 1 inch. Roads should remain ice free as temps remain steady in the lower 30s then climb to mid to upper 30s by noon Monday. Again higher elevations will stay cooler with steep lapse rates and very cold air aloft in this pattern. Will need to monitor for possible advisory criteria in higher elevations. SNELSON && .LONG TERM /Monday through Saturday/... The long term forecast picks up on Monday just as wrap around moisture on the back side of a low pressure system will be passing across northern Georgia with precipitation coming to an end. The forecast area should remain dry through about early Friday when the next system is expected to impact the area. There are some disagreements between models for timing of another upper level trough expected to impact the area Friday. The GFS has a quicker progression east than the ECMWF leading to earlier precipitation across the area early Friday. Have gone with a blend for pops, bringing slight change to chance pops early Friday with chances lingering through early Saturday. Models aren`t really showing much instability with this system, so have continued just chances for rain. Monday is expected to be the coolest day of the long term forecast with highs in the upper 30s and lower 40s across the north and in the mountains with upper 40s and mid 50s across central Georgia. Overnight lows into Tuesday morning will also be chilly with widespread temps in the upper 20s and lower 30s expected across the area. Temperatures will begin to moderate after that with highs through the extended generally in the 50s and 60s with lows in the 30s and 40s. Reaves && AVIATION... 00Z Update... VFR conditions expected thru 06Z-09Z when line of showers and some MVFR to near IFR cigs and vsbys move through. Isolated thunder possible but chance too low to include in taf at this point. Improvement expected shortly after precip moves out after 14z. Winds will stay southwest 10 to 15kts then west and and increasing to 12-16kts with gusts to 25+ kts after the line of showers moves thru and persisting all day Sunday. //ATL Confidence...00Z Update... Medium on MVFR/IFR cigs tonight. Medium-high on precip timing. High on all other elements. 41 && .PRELIMINARY POINT TEMPS/POPS... Athens 58 66 38 49 / 90 90 5 5 Atlanta 59 63 37 45 / 90 70 5 5 Blairsville 53 57 31 39 / 100 70 30 20 Cartersville 56 63 35 45 / 100 50 5 5 Columbus 63 68 40 51 / 80 80 5 5 Gainesville 58 63 37 46 / 100 70 5 5 Macon 59 69 40 51 / 60 80 5 5 Rome 55 61 36 45 / 90 30 5 5 Peachtree City 58 65 37 47 / 90 70 5 5 Vidalia 59 72 43 54 / 20 80 10 0 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...41 LONG TERM....Reaves AVIATION...41
Area Forecast Discussion
National Weather Service North Platte NE
528 PM CST Sat Nov 30 2019 .SHORT TERM...(This evening through Sunday night) Issued at 321 PM CST Sat Nov 30 2019 Wrap around light to moderate snow is expected to continue most of the night across north central Nebraska and exit early Sunday morning. The NAMnest model appears to have the best handle on the snow wrapping through wrn and ncntl Nebraska. Much of the snow/snow shower activity along Interstate 80 should dissipate around sunset or early this evening. The HRRR model and the consensus MOS plus bias correction was the basis for the wind forecast tonight and Sunday. This suggested gusts to near 60 mph this evening with speeds falling off after midnight; especially where breaks in the overcast develop across swrn Nebraska. The corridor of high winds across the srn Nebraska Panhandle and swrn Nebraska should shift east toward ncntl Nebraska tonight. The overcast skies across ncntl Nebraska tonight should maintain a mixed layer with strong or high winds continuing. This philosophy is backed up by the strong mixed layer winds shown by the RAP model. The short term model blend was the basis for the snow forecast tonight and it indicates 1 to 3 inches this evening and overnight. The Blizzard Warning will continue as wind speeds should increase as the sfc low begins to pull away from wrn and ncntl Nebraska. The temperature forecast overnight through Sunday night leans on the bias corrected short term model blend which was cooler than the deterministic short term model blend and the guidance blend. Lows should fall into the single digits for a few hours tonight and Sunday night. Return flow around a weak area of high pressure Sunday night will likely limit radiational cooling effects. .LONG TERM...(Monday through Saturday) Issued at 321 PM CST Sat Nov 30 2019 A dry forecast is in place through 7 days. The upper level flow will become mostly zonal sending Pacific high pressure into the central Plains. The temperature forecast respects the snow cover up north and highs in the 30s are in place along and north of highway 20. Highs will warm into the 40s along and south of Interstate 80. H850mb temperatures will be rising into the single digits above zero Monday and beyond which should support highs in the 40s where there is little or no snow cover. The models show an arctic high pressure system dropping through the nrn Plains and Midwest Thursday night next week. This system is progressive and should move off east fairly quickly. Wrn and north cntl Nebraska will on the "warm" or western side of arctic high and 30s to near 40 are in place for high temperatures Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 528 PM CST Sat Nov 30 2019 Blizzard conditions will continue through tonight for northern Nebraska terminals (KGRN, KVTN, KANW, KONL) with IFR visby at times. Scattered snow showers with brief visby drops will taper late this evening for southwest Neb (KOGA, KLBF, KBBW), but cigs remain MVFR. The very strong northwest surface winds will slowly lessen overnight, but gusts will exceed 20 to 25kts for virtually the entire forecast period. Low stratus clouds will begin to break late morning to early afternoon Sunday, giving way to VFR. && .LBF WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 6 AM CST /5 AM MST/ Sunday for NEZ022- 026>029-035>038-056>059-069>071. Winter Storm Warning until noon CST Sunday for NEZ007-010. Blizzard Warning until noon CST /11 AM MST/ Sunday for NEZ004>006-008-009-023>025-094. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively
National Weather Service Morristown TN
810 PM EST Sat Nov 30 2019 .UPDATE... EVENING UPDATE. && .DISCUSSION... An update will be issued to adjust PoP and Wx grids for the slightly faster movement of showers and scattered thunderstorms into the area. Elevated instability in the presence of strong QG forcing will keep a chance of thunderstorms going through the night. The main concern will be localized heavy rainfall that may lead to some minor flooding problems. The southern portions of the area may have the greatest potential for flooding over the next few hours due to training cells. DGS && .AVIATION... 00Z TAF DISCUSSION. Periods of rain will create highly variable conditions at the TAF sites through the night. A line of showers and thunderstorms is approaching from the west, and will cross the area between 00-06Z. TS and IFR conditions may occur at the TAF sites with this line. Predominany MVFR conditions are expected to follow but with IFR possible at times. VFR conditions should return around 12Z behind a cold front, along with an increase in winds and wind gusts, up to 30 kts possible. DGS && .PREV DISCUSSION... /ISSUED 307 PM EST Sat Nov 30 2019/ SHORT TERM (Tonight and Sunday)... Complex weather occurring during the short term period. A large vertically stacked cyclone is currently across the Great Plains with a cold front across the Mississippi River Valley. Deep southwesterly flow is ahead of this front resulting in isentropic ascent across the forecast area. This is resulting in unseasonably high moisture with HREF guidance placing 1.3 to 1.5 inch PW values across most of the forecast area, which is near the maximum for this time of year. This, along with elevated instability and a few embedded thunderstorms, will aid some locally higher rainfall totals of 2 to 3 inches in spots while most locations will remain in the 1 to 2 inch range. Temperatures will also remain unseasonably warm tonight within the southwesterly flow ahead of the front. Strong winds will also be a factor tonight across the higher elevations and adjacent foothills. This is not an ideal mountain wave high wind event with the cyclone location and SSW wind direction, but with the GFS, ECMWF, NAM, and RAP all in agreement with a 50+ 850mb LLJ structure across the TN Valley and Southern Appalachians, believe there is a high likelihood of at least 50 to 55 mph winds across the higher elevations, including the US 441 corridor. There is also a strong pressure differential across the mountains which will increase the probability for some wave events and associated higher winds in the adjacent foothills. For this reason, have issued a wind advisory for the higher elevations of the mountains along the TN/NC border. This will need to be monitored tonight and may need to be upgraded to a warning if conditions warrant. A majority of the precipitation moves east on Sunday with drier air advecting into the area on Sunday morning behind the cold front. The air behind the cold front will not be very cold, but will actually be near normal for this time of year. A secondary cold front will bring much colder air to the region Sunday evening and into the overnight hours. JB LONG TERM (Sunday night through Saturday)... The center of the low pressure system that impacts the forecast area this weekend shifts east southeast out of the Upper Ohio Valley across the Middle Atlantic Coast and out to sea through the first 36 hours of the long term. Model forecasts are resolving the system a little better, showing a brief period of deeper moisture and lift late Sunday night into Monday morning for some likely and categorical pops for mainly Southwest Virginia and Northeast Tennessee. Precipitation will be primarily in the form of rain as the event begins, but enough cold air will be building into the region; especially above two thousand five hundred feet for the light rain to change over to some light snow. Across lower elevations over much of the remainder of the forecast area, low level temperatures will stay just above freezing, so the light rain will be mixed with some light snow with very limited accumulation expected. However, in the higher terrain there will be some light accumulation which may last well through the day Monday while fading from south to north through Monday night. In the cold air advection, northwest flow pattern typical with a system like this, snowfall will accumulate with in the higher terrain across Southwest Virginia and Northeast Tennessee southwest through the Smoky Mountains. In these areas, snowfall amounts could be in the one to three inch range, with locally higher amounts possible during the 36 hour period ending at 12z Tuesday morning. Following the departure of this system, the forecast area may be able to squeeze out a few hours of sunshine on Tuesday before the next upper trough drops southeast out of Canada. This system still looks a little moisture starved and relatively weak for the possibility of precipitation, so maintained a mid week dry period. The American and European models are still not entirely on the same page with a late work week southern stream feature that has a surface reflection tracking well south of the forecast area. Strongest lift and better moisture still appears to be farther south across the Deep South region with this short wave. However, there will be some isentropic ascent north of the surface low and there could be just enough moisture ahead of another cold front associated with a northern stream wave building through the Eastern Great Lakes and Northeastern U.S. at this time for some light rain, so kept this concept going late Thursday night into Friday. Due to model differences with the progression of a deepening Western U.S. trough at the end of the long term forecast on Saturday, stayed with a dry forecast while awaiting better model resolution. && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...Wind Advisory from midnight tonight to 7 AM EST Sunday for Johnson-Southeast Carter-Unicoi. Wind Advisory until 7 AM EST Sunday for Blount Smoky Mountains- Cocke Smoky Mountains-Sevier Smoky Mountains-Southeast Greene-Southeast Monroe. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Mount Holly NJ
948 PM EST Sat Nov 30 2019 .SYNOPSIS... Low pressure will move from the plain states towards the lower Great Lakes tonight into Sunday. A secondary low is expected to develop in Virginia, Maryland and Delaware by late Sunday. The secondary low is anticipated to intensify as it moves slowly to the northeast, reaching Nova Scotia on Tuesday afternoon. High pressure should gradually build into our region from the west and southwest during the balance of the work week. A cold front may approach from the northwest late on Friday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... No big changes to the forecast so far this evening. The overall trend looks good. We have made some hourly temperature and dewpoint adjustments, but the overall forecast still looks good. Precipitation will begin to move into portions of southeast Pennsylvania, southern New Jersey, Delaware and eastern Maryland around or shortly before daybreak. Delaware and Maryland, should remain mostly above freezing and be all rain, except possible the extreme northern portions of Cecil and New Castle counties where a brief period of freezing rain or sleet may occur before warming up. The same is expected for southern New Jersey where temperatures are currently below freezing. Temperatures are expected to rise late in the night just before precipitation begins. So if there is any freezing rain or sleet, it is expected to be brief. So the advisory was not adjusted at this time. The more likely areas for freezing rain to occur is farther north across Pennsylvania and central/northern New Jersey. Precipitation likely will not begin for central/northern New Jersey and northeast Pennsylvania until after daybreak. However, portions of southeast Pennsylvania is expected to have precipitation move into the area shortly before daybreak when temperatures will remain below freezing. Therefore the advisories remain in place where they area. This will just be the very beginning though and for further details please see sections below. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... Sunday-Monday... The storm arrives. A complex, two-phased winter storm remains on track to impact the area. There have not been any big changes in the overall forecast thinking, with just typical adjustments to the forecast based on latest trends and thinking. I do want to break down headline decisions, however, as it is a complicated situation in that regard. A Winter Storm Warning has been issued for portions of northern New Jersey and the Poconos. This covers the entire expected storm duration to cover the anticipated combination of snow, sleet, and freezing rain. There are two tiers of Winter Weather Advisories in effect. The southern tier, covering southeast Pennsylvania including Philadelphia, has been issued to cover the potential for a period of snow, sleet, and freezing rain Sunday morning, and it expires early Sunday afternoon. The northern tier of advisories covers some additional zones to the northeast, and that advisory is in effect for the entire duration of the storm, as wintry impacts are expected to continue through the day Monday due to the second period of steady precipitation. That advisory may need to be expanded southward in future updates once the first phase of the storm is out of the way, and if snow amounts for Monday were to increase then portions of it could be upgraded to a warning. Otherwise, still looking at a very complex, two-phased winter storm affecting the area as occluding low pressure over the Midwest redevelops offshore. Phase One, Sunday morning through evening: This will be the overrunning precipitation phase as we get into a southerly flow WAA regime with the weakening parent low to our west and the secondary low developing along our coastline. Due to wet bulbing effects, many areas even along I-95 will likely start at least briefly as snow, sleet, or freezing rain. A quick change to rain is likely inside of I-95, but signals remain strong for a prolonged mixed precip event across the interior. High pressure centered to our north over Quebec is in a fairly classic position to lock in low level cold. Ptype remains a bit of a question mark. Have been fairly bullish on sleet potential versus snow or fzra. Today, some guidance has trended towards more fzra, though most forecast profiles to me still look more supportive of mostly sleet. The 30.12z RGEM looked reasonable to me, and as that tends to be a reliable model anyways I leaned on it pretty heavily, with some blending of the NAM and other hi-res guidance. Some of our northernmost zones will also stay as all snow for a time Sunday, and some hi-res guidance such as 30.18z HRRR would suggest my snow amounts up north tomorrow are too low. But will let a fresh set of eyes reevaluate. QPF on Sunday is fairly impressive for an overrunning event as the dynamics are on the strong side. Given expectations for temperatures to remain below freezing most of the day in the interior, it will likely be a very messy day in northern and western parts of the area regardless of exact ptype, as any combination of steady precipitation and below freezing temperatures creates hazardous conditions. As overrunning precip lifts north and secondary low pressure development continues, a lull in precipitation is expected Sunday evening. Some lingering showers or drizzle remain possible during this time, and there could be continued light freezing rain or freezing drizzle in our northern zones during the evening. Phase Two, late Sunday night and Monday: This is where the uncertainty remains higher. Signals remain for a band of snow, potentially heavy and also potentially enhanced by an inverted trough, to impact northern parts of the area. There is considerable spread in how strong that band will, where it will focus itself, and how far south it will make it. But a transition from rain or freezing rain to snow is likely late Sunday night or Monday morning in the northern portion of the area, and there remain indications for the potential of several inches of snow especially in the areas where the Winter Storm Warning is in effect. Again, some changes are likely for this time especially if the main band of heavy snow ends up being both as strong and as narrow as some models suggest. But it is too early to begin creating the sharp snowfall gradients associated with pinning down such a band. **Summary/Key Points**: Travel across the interior is likely to be very difficult on Sunday, especially as it is already a busy holiday return travel day. While ptype remains somewhat uncertain, am fairly confident that much of the day will feature steady precipitation with sub-freezing surface temperatures, which is always going to cause problems on the roadways. Lesser but non-zero impacts are possible in the morning as far southeast as I-95. For Sunday night and Monday, there remains some uncertainty in the forecast. However, several inches of accumulating snow and associated travel impacts remain likely across portions of northern New Jersey and eastern Pennsylvania. Users should continue to closely monitor the forecast. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... By Monday night, uncertainty remains a bit high on the evolution of precipitation and amounts. However, it does appear that wrap around precipitation amid deformation banding will be transitioning quickly from rain to snow from north to south Monday evening. Guidance differs on intensity and accumulation of precipitation, however I was confident enough to include likely PoPs across the northern tier for the evening and early overnight. Precipitation is forecast to move completely out of the forecast area by daybreak on Tuesday. I made some minor adjustments to the snowfall forecast during this time. If the forecast trends more in the direction of the 12Z ECMWF, would likely get a few inches of snow down across central and northern NJ including the northern Shore as the band exits, but changes in the forecast are likely during this forecast period so we did not include any headlines for these areas at this time. Heavier snow is still forecast across the areas where the Winter Storm Warning has been issued, so this headline will cover this activity. Went a bit colder than guidance for Monday night and Tuesday given ongoing snow and snow cover across the north. Please continue to monitor changes to the forecast during this period as accumulating snowfall is forecast as the long duration winter storm departs the region, but uncertainty remains. Did not focus much attention on the periods beyond Monday night, but blended in a bit of the latest consensus guidance. Previous discussion follows... We should remain in a cyclonic flow pattern for Wednesday into Thursday. As a result, there may be some stratocumulus overhead at times, with a passing sprinkle or flurry possible. Daytime highs should favor the 40s, with readings not getting above the 30s in the elevated terrain. A cold front is expected to approach from the west on Friday. However, any precipitation associated with the front should not arrive until late in the day. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight... Mostly VFR with lowering cigs from S-N after midnight. Winds remaining 5-8 knots or less but shifting from N/NW to NE through this evening and then E/NE by morning. Sunday... MVFR-IFR conditions expected with primarily rain at MIV and ACY. A mix of rain, sleet, and possibly freezing rain at northern terminals (particularly RDG and ABE). The MVFR conditions should set in through the morning with IFR arriving around midday. Easterly winds around 10 kts. High confidence winds and flight categories, moderate confidence in precipitation types. Confidence is increasing that the I-95 terminals will experience at least a couple hours or more of freezing rain and sleet before changing to rain, especially PHL northward. OUTLOOK... Sunday night...IFR conditions with periods of rain. The rain is expected to transition to a wintry mix at KABE and KRDG after midnight. Winds remaining around 10 knots but shifting from NE to NW. Medium confidence. Monday...IFR with mainly snow at KABE and KRDG. Mainly IFR with rain changing to snow at our remaining six TAF sites. There could be brief periods when conditions improve to MVFR during lulls in precip. An accumulating snow is possible, especially at KRDG, KABE and KTTN. Northwest wind increasing to 10 to 15 knots. Medium confidence. Monday night...Snow ending with conditions gradually improving from to VFR. Northwest wind 10 to 15 knots with gusts around 20 knots. Medium confidence. Tuesday...VFR. Northwest wind 10 to 15 knots with gusts around 20 knots. Medium confidence. Tuesday night...VFR. West wind 5 to 10 knots. Medium confidence. Wednesday...VFR. West wind around 10 knots. Medium confidence. Thursday...Mainly VFR with NW winds around 10 knots. Medium confidence. && .MARINE... Tonight...Sub-SCA conditions expected. East winds around 10 kts and seas 1-2 feet. Sunday...SCA conditions developing across all ocean waters throughout the day. Easterly winds will be gusting up to 25 kts with seas building to around 4-5 feet later in the day. Gale force wind gusts possible north of Barnegat Light late in the afternoon and early evening as the center of low pressure moves offshore and rapidly intensifies. Waves will be higher in these areas. Issued a Gale Watch for this period. OUTLOOK... Sunday night...Marginal SCA conditions will persist through the overnight with west to northwesterly winds gusting 20-25 kts and waves 4-7 feet. Monday through Tuesday...Northwest winds gusting to around 25 kts and waves 4-6 feet. Confidence on SCA conditions is highest overnight Monday night when wind gusts may reach up to 30 kts. Tuesday night through Thursday...Conditions are forecast to remain below SCA criteria. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Winter Storm Warning from 4 AM Sunday to 1 AM EST Tuesday for PAZ054-055. Winter Weather Advisory from 4 AM Sunday to 1 AM EST Tuesday for PAZ061-062-105-106. Winter Weather Advisory from 3 AM to 1 PM EST Sunday for PAZ060-070-071-101>104. NJ...Winter Storm Warning from 4 AM Sunday to 1 AM EST Tuesday for NJZ001-007-008. Winter Weather Advisory from 4 AM Sunday to 1 AM EST Tuesday for NJZ009-010-012-015. DE...None. MD...None. MARINE...Small Craft Advisory from 10 AM Sunday to 1 AM EST Monday for ANZ452>455. Gale Watch from Sunday morning through late Sunday night for ANZ450-451. && $$ Synopsis...Fitzsimmons Near Term...Fitzsimmons/Robertson Short Term...O`Brien Long Term...Iovino/Staarmann Aviation...Fitzsimmons/Staarmann Marine...Carr/Iovino/Staarmann
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday) Issued at 341 PM CST Sat Nov 30 2019 As of 21Z, water vapor imagery showed a tight cyclonic circulation near the Nebraska and South Dakota state line. This strong storm system brought rain and thunderstorms to the area last night and is providing gusty winds across the region today. Some locations in north-central Kansas were gusting to near 50 mph as of mid afternoon. Winds will continue to increase this evening and overnight in response to a tightening pressure gradient over the area as the storm system pivots into Iowa. A 50 to near 60 kt LLJ will set up over the area tonight. RAP forecast soundings show mixing to near 850mb through most of the night, which could allow those higher winds to mix down toward the surface. The strongest winds are expected to occur where the pressure gradient will be greatest, mainly over north-central and far northern Kansas. As such, the High Wind Warning continues for north-central Kansas until 15Z Sunday where sustained winds will be between 30 and 40 mph with gusts to near 60 mph possible. The rest of the forecast area will be in a Wind Advisory until 15Z Sunday with sustained winds between 25 and 35 mph with gusts to 50 mph possible. There will also be a chance for light rain/snow, or even a light wintry mix for areas near and north of Interstate 70 tonight in a zone of wrap-around precipitation. Impacts are expected to be minimal since QPF will be very light. Cloud cover will stick around into tomorrow afternoon but conditions will be dry. Winds will begin to subside during the late morning hours as the pressure gradient relaxes. CAA and cloud cover will limit temperatures to the 30s tomorrow. .LONG TERM...(Sunday night through Saturday) Issued at 341 PM CST Sat Nov 30 2019 The long-term portion of the forecast period is looking fairly settled, with only one system that could bring precip back to the region. Upper level ridging and surface high pressure will work into the area on Monday. Ridging will allow temperatures to be near climatological normals (mid 40s for highs and upper 20s for lows) under sunny skies. An upper level shortwave will move over the region on Tuesday but no precip is expected with that system. Surface winds will shift from the southwest to the northwest, but temperatures are expected to warm into the 50s with no evidence of CAA occurring in response to northerly winds. From midweek into late week, an upper low will traverse the southern tier of the country. That system will pass south of the area on Thursday, bringing our next potential chance for precipitation. Models are indicating dew points returning to the 40s in eastern Kansas ahead of the system. There may be enough lift to allow for light precipitation in eastern Kansas and both the Euro and GFS show at least light QPF across the southern CWA. Otherwise, conditions will remain fairly quiet into the start of next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 531 PM CST Sat Nov 30 2019 Strong west to northwest winds of 20 to 30 kts with gusts of 40 to 50 kts persist through the overnight hours, gradually subsiding through the day on Sunday. MVFR to low VFR stratus work through much of the area tonight through Sunday, with light rain/snow mainly north of the TAF sites before sunrise tomorrow. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 9 AM CST Sunday for KSZ009>012-021>024-026- 035>040-054>056-058-059. High Wind Warning until 9 AM CST Sunday for KSZ008-020-034. && $$ SHORT TERM...Teefey LONG TERM...Teefey AVIATION...Skow
Area Forecast Discussion
National Weather Service Las Vegas NV
720 PM PST Sat Nov 30 2019 .SYNOPSIS...Considerable cloudiness will spread across the region ahead of another Pacific System that is expected to mainly impact the central and northern Sierra Sunday and Monday. This system will move inland and bring chances of precipitation to much of our area by Wednesday then move away by Thursday for a brief dry period followed by more unsettled weather next weekend. && .UPDATE...Shallow wedge of warm air advection captured on our Vegas afternoon sounding providing enough lift for continued area of light stratiform rain across the western Mojave Desert and Morongo Basin this evening. As warm air advection weakens, HRRR and 00z NAM indicate light precipitation receding back westward into the Tehachapis and southern Sierra late tonight through Sunday. Guidance still shows narrow plume of moisture associated with higher rainfall rates remaining aligned from just south of Monterey Bay northeast into the Tahoe Basin Sunday night into Monday. Am not expecting any heavy rainfall over the snow cover at the Taboose Burn Area in Inyo County. Tweaked our POPs across San Bernardino County for the rest of tonight, no other changes. && .PREV UPDATE...352 PM PST Sat Nov 30 2019 .UPDATE...Light rain falling as far east as Barstow this afternoon. Updated our grids to increase POPs across the western Mojave Desert of San Bernardino County. No other changes at this time. && .DISCUSSION...Considerable mid and high clouds will spread across our region and produce a dense overcast this evening and overnight, but precipitation will be largely intercepted in California by the coastal ranges and Sierra. Our southern Sierra and Owens Valley zones will see the potential for some light snow, but most of the precip will occur west of the Sierra Crest. The broad closed low off the northern California Coast that was directing a long plume of subtropical moisture into California should keep the associated atmospheric river oriented toward central and northern California Sunday and Monday with only light precip possibly spilling over into the Owens Valley. Cold air trapped in the Owens Valley should result in snow tonight though snow levels will be rising to above 7000 feet Sunday into Monday. The potential for freezing rain Sunday night and Monday night is not out of the question, but a deep layer of cold air in the Owens Valley may result in refreezing of any melting precip into ice pellets. Something to keep a close eye on. There is good agreement among the models that the eastern Pacific System will dig toward southern California Tuesday then moves fairly quickly inland Tuesday night and Wednesday. However, there is still some uncertainty in timing and track. Either way, much of our region will likely see another round of precipitation with any particular site probably in a 6-9 hour window of precipitation. Any snow accumulations will generally be at elevations above 6000 feet. The system is forecast to pull away quickly Wednesday night followed by generally dry conditions Thursday. A large eastern Pacific trough approaching the coast will then bring chances of precipitation back into the forecast area late Friday into Saturday. && .AVIATION...For McCarran...Light and variable wind expected to continue through tonight and tomorrow, favoring typical diurnal directions. Increase in cloud cover and lower ceilings are expected through this evening. Ceilings should remain SCT-BKN aoa 8-10 kft. For the rest of southern Nevada, northwest Arizona and southeast California...Mostly light and variable winds expected across the region through today and tomorrow. Some breezy southeast winds are possible at KBIH this afternoon through the overnight period accompanying vicinity snow showers, but should generally remain below 10-15 knots. Best chance of seeing snow showers at KBIH will be early tomorrow morning, mainly after 12-15Z. Visibility and ceilings will decrease with these snow showers with visibilities dipping as low as 4SM at times and BKN to OVC ceilings aoa 6-8 kft. Elsewhere will remain dry with increasing to mid to high clouds. && && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce DISCUSSION...Adair AVIATION.....Kryston For more forecast information...see us on our webpage: or follow us on Facebook and Twitter