Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/02/22

National Weather Service Kansas City/Pleasant Hill MO
558 PM CST Tue Feb 1 2022 .Discussion... Issued at 327 PM CST TUE FEB 1 2022 Key Messages: - Winter storm still expected to impact the area tonight through Thursday. This winter storm really looks like it can be broken down into two distinct events that blend together. The first event really gets going this evening through late Wednesday morning or early Wednesday afternoon. The second, Wednesday evening into Thursday afternoon. It`s this second round that is leading to a lot uncertainty with the storm total snowfall due to a tight gradient on the northern side of the precipitation area from no snow to heavy snow. When the gradient is this tight, literally a county to county and half wide, any minor movement in the system really affects snow amounts in that gradient area. For the first event, a well pronounced coupled jet structure develops over the region. This induces strong upward motions and strong isentropic ascent that is most notable on the 290K surface but also noted at 285K and 295K before weakening higher up at 300K. In the lower levels, strong frontogenesis develops enhancing the overall vertical motions. This area of frontogenesis really shows up well in the 800MB to 750MB layer develops over the northern half of the forecast area before sliding south through the evening and overnight hours, eventually moving into southern MO by tomorrow morning, helping wind down, but not completely end, the first round of snowfall before the second round begins. The strong forcing with the coupled jet, deep isentropic ascent, and the strong frontogenesis will lead to sizable accumulations and potentially most of the snowfall for the KC metro between the two events. Within this first round of precipitation, there will be a short window of mixed precipitation, especially further south, as there remains an elevated warm nose initially. This is mostly eroded by cold advection aloft but may be aided by the increase in upward vertical motions cooling the column as well. Regardless, there may be some sleet and freezing rain, mainly across our southern zones as the area transitions from rain to snow. For the second round of precipitation, the main upper shortwave trough will begin to move across the middle of the country. At the surface, a strong high pressure area will be moving southward. There is very dry air associated with this high pressure area that will be advecting into the northern half to three quarters of the forecast area. This dry air may be too much to overcome for the lift associated with the wave and as a result, the northern extent of the snow area may be farther south. There remains considerable uncertainty though regarding this. Most 12Z guidance seemed to indicate more of a southward trend in this second precip area as the dry air looked to dominate over the forcing. But some of the latest 18Z guidance casts some doubts about that. The 18Z HRRR and the NAM 3km both bring snow back into the area late Wednesday afternoon and evening. That said, it still is more likely that the heavier snow with this second round will be across the southern fourth of the forecast area, mainly south of I-70. Bitterly cold air will settle into the region, particularly Friday morning when lows fall to around 0F. From then on there will be a warming trend into next week as temperatures may climb back closer to normal for this time of year. That could be modified downward due to lingering snow cover. Otherwise, the extended portion of the forecast looks quiet for now. && .Aviation...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 558 PM CST TUE FEB 1 2022 Precipitation is beginning to fall at most of the terminals. Rain is expected to transition over to snow over the next couple of hours. Snow is expected to overtake the region overnight and continue through Wednesday. Periods of heavy snowfall may temporarily reduce CIGs and VIS to IFR. Timing of IFR conditions remains sporadic and uncertain. It is anticipated that dips to IFR will correlate with the heaviest rates of snowfall which are expected tomorrow morning. Northerly winds around 12-18 kts prevail with gusts of 25-30 kts possible throughout the entire forecast period. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Winter Storm Warning from 9 PM this evening to 6 PM CST Thursday for KSZ057-060-103>105. Winter Weather Advisory from 9 PM this evening to 6 PM CST Thursday for KSZ025. Winter Weather Advisory from 9 PM this evening to noon CST Wednesday for KSZ102. MO...Winter Storm Warning from 9 PM this evening to 6 PM CST Thursday for MOZ017-021>025-028>033-037>040-043>046-053-054. Winter Weather Advisory from 9 PM this evening to 6 PM CST Thursday for MOZ008-013>016-020. Winter Weather Advisory from 9 PM this evening to noon CST Wednesday for MOZ004>007-011-012. && $$ Discussion...CDB Aviation...Pesel
Area Forecast Discussion
National Weather Service Wichita KS
808 PM CST Tue Feb 1 2022 ...Winter Mesoscale Update... .MESOSCALE DISCUSSION... Issued at 802 PM CST Tue Feb 1 2022 As of 02z/8pm, the left exit region of the upper jet is moving into the Southern Plains, providing a more diffluent flow aloft across Kansas/Oklahoma. The increasing large-scale forcing is becoming more evident on radar imagery, showing an expanding field of precip across central/eastern KS. Additionally, low-level WAA is increasing (per recent RAP analyses and radar imagery) across southern KS, with continued CAA to the north, leading to a tightening baroclinic zone and increasing low-mid level frontogenesis across the area. The increasing large-scale, and mesoscale, lift plus the incoming plume of subtropical moisture is aiding in a deepening layer of moisture, and this process should continue in earnest through the night. RAP soundings reveal steep lapse rates above the baroclinic zone and this appears to be contributing to the more showery/convective look to the precip on radar. However, with time, the layer above the frontal zone is forecast to stabilize, favoring a more solid, and steadier, band of stratiform precip developing from NW to SE through the night. It`s in this band of precip that we should see some light to moderate snowfall rates (0.25"-0.75"/hr) develop, with accumulating snow becoming increasingly likely. Where frontogenesis is strongest/most persistent, there could be a brief period where snowfall rates approach 1"/hr. However, the transient nature of the mesoscale lift should keep the threat of those higher rates low. Where precip is the heaviest at this hour, wet-bulb processes have led to a quick drop in temps down into the low 30s. In fact, parts of south-central KS are colder than north-central KS due to this process. Given the quicker fall in SFC temps, the ptype has transitioned over to freezing rain/sleet/snow a little quicker than expected, and the forecast has been adjusted to reflect this trend. Road temps are also falling, but lag about 3 degrees behind the air temps. Based on this trend, it will probably take temps falling into the upper 20s before road impacts begin to increase more, which should occur between 9pm-12am across central/south- central KS, and after midnight across SE KS. Despite the earlier onset of wintry precip across south-central KS, we don`t currently anticipate a significant change in ice or snow accums as a lot of this early wintry precip will get lost to melting. Current headlines will still start as is, even with the sooner change to frozen/freezing precip, because the impact period will still hold off until later this evening. Martin && .SHORT TERM...(This evening through Friday night) Issued at 423 PM CST Tue Feb 1 2022 Highlights: 1) Rain/drizzle this evening transitioning to wintry mix then all snow 2) Moderate snowfall tonight through Wednesday 3) Dropping temperatures 4) Dangerous wind chills Thursday and Friday mornings Changes: Decreased temperatures Wednesday-Friday Challenges: 1) Exact timing of transition to all snow 2) End time of snowfall Headlines: Winter Storm Warning from 9PM tonight to 6AM (SC)/12PM (SE) Thursday Winter Weather Advisory from 9PM tonight to 6AM Thursday (NC) A low pressure system is situated over the Plains. Moisture advection continues to push north. There is a bit of lift to bring drizzle and just recently reports of mixed precipitation. As the system moves further east, this will increase the coverage through the evening and overnight. A wintry mix is still anticipated this evening into tonight; southeast Kansas will have the longest duration of a wintry mix from roughly midnight into Wednesday morning. The wintry mix could include freezing rain and sleet as well as snow of course; potential ice accumulation around a tenth of an inch is forecast in southeast Kansas. There is still some question on the exact timing of the arrival of cold air or respective cloud ice to transition the precip type; in southeast Kansas, questionable changeover timing to all snow could in turn impact any ice or even snow accumulation initially. The best period of lift is from roughly 10PM tonight through mid morning Wednesday. Coincidentally this timeframe aligns with the transition to all snow as the cold air moves in. There could be some banding with the snowfall due to frontogenesis meaning that locally higher amounts are possible. A wet surface from any rain will initially make it harder for the snow to stick. However, this time period does coincide with the best lift as mentioned which means moderate snowfall is possible. A second round of moderate snowfall is expected primarily southeast of the Kansas Turnpike Wednesday evening/night to add onto their totals. Light snow is expected throughout the day on Wednesday, so there will not necessarily be an elongated break between the rounds. The overall lift for this system is not necessarily overly impressive across the area with the better lift to the east and south. In this case, it will essentially be an extended period of snow (tonight-Thursday) with a deep dendritic snow growth zone to help bring amounts of roughly three to nine inches. This forecast does align with the previous one in terms of timing and amounts. Winds are another factor that will create a problematic scenario with sustained speeds around 20 mph with gusts to 30 mph. Therefore this will blow the lighter/fluffy snow given the thermal profile. Coincidentally visibility reductions would occur. Another factor is blowing and drifting snow; this is expected especially on east/west running roadways given the northeast to northerly winds. As mentioned cold air will move in to further drop temperatures. Highs on Wednesday and Thursday are only forecast to reach the upper teens to lower 20s. There was a decrease with this forecast issuance closer to the 25th percentile of the NBM given clouds and snow cover. Overnight temperatures will drop down to the single digits Thursday morning and Friday morning. A 1040mb high pressure system will push cold air down from the north which will come over the fresh snow resulting in a cold start to Friday with low temperatures around 0 degrees. Even though light winds are expected, wind chills are forecast to range from 5 to 15 below zero both on Thursday and Friday. If you head out, make sure to bundle up and don`t forget about your pets. A wind chill headline may be needed for Friday morning, but Thursday morning`s wind chills have been mentioned in the current headlines to keep things simple. .LONG TERM...(Saturday through Tuesday) Issued at 423 PM CST Tue Feb 1 2022 Highlights: 1) Gradual warm up but hinges on snow cover 2) Dry A gradual warm up is expected for the end of the week into the weekend, but this does hinge on the snowpack which could keep temperatures lower. Given the snowpack, there have been slight modifications to the temperatures. The forecast continues to have afternoon highs back above the freezing mark (32 degrees) on Saturday. Models are showing a couple of short waves coming across through the weekend, but they appear to be dry in nature. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 613 PM CST Tue Feb 1 2022 * Winter storm underway. Widespread aviation impacts through THU As of 23z/5pm, precipitation is beginning to expand in coverage and intensity across the area. Below is a breakdown of the expectations across the area this evening/overnight. NORTH-CENTRAL KS (KRSL/KSLN/KGBD) - Precipitation will mostly fall as SN, but may begin as a brief period of PLSN. CIGs will be slower to fall in this area, and, for now, are expected to hold at VFR for most of the night. Total snow of 2-5" expected. SOUTH-CENTRAL KS (KHUT/KICT) - Precipitation will start as RA and PL, then transition to SN between 03-06z. SN will then be the predominant precip type through the remainder of the night. The risk of FZRA looks minimal, and will be short-lived if it occurs at all. The main risk for a brief period of FZRA will be at KICT. FZRA is not expected at KHUT. CIGs should hold steady in the MVFR range through the night, but could dip close to IFR as the steadier SN develops. Total snow of 4-7" expected. SOUTHEAST KS (KCNU) - Precipitation will be mostly RA, moderate at times, for most of the evening. By 06z, the precipitation will begin to transition to a FZRAPL mix as surface temps fall below freezing. By Wednesday morning, the precipitation will transition to mostly SN. The lowest CIGs and VIS will occur as the SN begins, with mostly MVFR conditions prior to that. IFR conditions will be possible late tonight through Wednesday, but I kept the TAFs more conservative for now as low-level dry air advecting into the area may tend to keep CIGs from falling too much. Total ice accumulation of a light glaze to around 0.10". Total snow of 4-8" expected. EXTENDED PLANNING OUTLOOK: Wintry precipitation (mostly SN) will continue to impact aviation through Thursday, with the greatest impact expected across southeast Kansas. Martin && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 18 20 7 18 / 90 100 80 10 Hutchinson 15 19 5 18 / 90 100 70 10 Newton 16 17 5 17 / 90 100 70 10 ElDorado 18 18 7 17 / 100 100 80 10 Winfield-KWLD 20 22 8 17 / 90 90 80 20 Russell 13 18 3 21 / 90 90 40 0 Great Bend 13 18 3 19 / 90 100 70 10 Salina 15 19 5 22 / 90 90 30 0 McPherson 15 17 4 18 / 90 90 50 10 Coffeyville 22 24 11 21 / 80 90 90 20 Chanute 19 21 10 20 / 90 100 90 10 Iola 19 20 10 19 / 90 100 90 10 Parsons-KPPF 21 22 10 20 / 90 90 90 20 && .ICT WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until noon CST Thursday for KSZ053-070>072- 095-096-099-100. Winter Storm Warning until 6 AM CST Thursday for KSZ050>052- 067>069-082-083-091>094-098. Winter Weather Advisory until 6 AM CST Thursday for KSZ032-033- 047>049. && $$ MESOSCALE...RM SHORT TERM...VJP LONG TERM...VJP AVIATION...RM
Area Forecast Discussion
National Weather Service Indianapolis IN
944 PM EST Tue Feb 1 2022 .Forecast Update... Issued at 944 PM EST Tue Feb 1 2022 Made some minor tweaks to PoPs, otherwise, radar was showing bulk of the rain was lifting northeast across the Wabash Valley. Still, expect the rain to spread southeast through the night. Temperatures were on track and still in the middle 40s over northern sections and upper 40s and lower 50s elsewhere. The HRRR BUFKIT LAF sounding supports a changeover to sleet or perhaps freezing rain after 4 AM for northwestern sections and then a quick transition to all snow. The transition zone should then get as far south as a Kokomo to Crawfordsville line by 7 AM. Areas north of this line could see upwards of an inch or slightly more of snow overnight along with light icing. This will cause some travel difficulties for the morning commute. Timing is handled well in web site and social media graphics. && .Short Term...(This evening through Friday) Issued at 258 PM EST Tue Feb 1 2022 Highlights: -- High confidence in a significant, high-impact winter storm especially for areas near and north of Indianapolis, but not excluding other portions of the area. -- Uncertainties remain with amounts and timing of precipitation type transition. -- Precipitation type transition order: Rain, freezing rain, sleet, and eventually snow. Quicker transition period north, and slower transition south. -- Greater snowfall accumulations in northern and portions of central Indiana, and greater ice and sleet accumulations across southern Indiana. -- Snow amounts and water content could cause snow load issues, with property damage possible (i.e., trees, power lines, and some roofs). -- Dangerous cold possible Saturday morning including possible sub-zero temperatures. Messaging Recommendations: -- Focus should be on significant impacts to daily life including difficult to nearly impossible travel, and not necessarily on specific amounts of snow and ice as some uncertainty remains. -- Magnitudes of impacts for portions of the area could rival or exceed some of our noteworthy past events including 1-2 February 2011, 14 February 2007, and 23 December 2004. -- For further historical perspective, in Indianapolis, 10 inches or more of snow in a two day period is a top 25 event. 11.5" or more is a top 10 event. 16.1" is the record two day snow amount. Meteorological Analysis and Uncertainties: Potential scenarios have narrowed as model spread has decreased at this stage. There are a few areas of uncertainties for portions of the forecast that we will highlight below, but in general this is a fairly high-confidence forecast, albeit with inherent uncertainties related to precipitation type transitions. On the synoptic scale, water vapor channel imagery shows a well- defined shortwave trough moving from Lake Superior northeastward into Ontario with an increasingly active southern stream into the Southwest part of the country. Advected Layer Precipitable Water shows an anomalous surge of deep moisture up through the Mississippi Valley with strengthening warm advection attached to aforementioned Ontario shortwave trough. Radar echoes are already noted in eastern Illinois into west-central Indiana and these will continue to expand as warm/moist advection regime increases. We will enter a prolonged period of anomalous moisture and ascent tonight, although there were be two distinct periods of stronger ascent and deeper saturation. (1) during the day Wednesday, followed by a lull in the heavier precipitation rates across the south, and (2) early Thursday morning through at least mid-afternoon with the second shortwave trough. In between, ascent and moisture will still be present for precipitation but veering/weakening flow with departing wave in Canada will favor generally light anafrontal precipitation, except across northwest near the southwest- northeast midlevel baroclinic zone. This is where frontogenesis is quite strong and rates may be quite intense (2+ inches/hour) with mesoscale banding. Also, as heavier precipitation rates depart, trailing light-moderate deformation band could bring additional light snow with higher snow-liquid ratios Thursday evening/night, particularly across southern portions of the area. This event differs from a more classic mid-latitude system in that a dry conveyor belt isn`t at play to end precipitation quickly, and an intense/anomalous closed midlevel low with well-defined deformation to its north. Instead, while there will be some periods of strong ascent, duration is the key factor with this event. Several hours of at least moderate to occasionally strong omega within the dendritic growth zone is indicated in NWP starting early Wednesday and continuing through late Thursday. The trend has been for quicker cold air arrival than earlier model runs, and we have adjusted timing of precipitation transition accordingly. This gives us enough confidence to upgrade the Winter Storm Watch to a Winter Storm Warning for our entire area (including our southern Indiana counties). By around midnight Wednesday night our entire area should be below freezing, and it is possible if trends continue we may need to speed the arrival of sub-freezing temperatures further. Uncertainty in forecast details increase slightly into Thursday given run-to-run model differences with timing/amplitude of the second wave, now organizing near California. GEFS ensemble spaghetti plots of 500-mb contours is clustered enough that we`re confident in another period of deeper ascent/moisture that could be fairly significant on Thursday. For all locations, the progression of precipitation type will be rain, to a brief period of freezing rain, to sleet to snow. This transition will occur quicker in the north than the south as warm nose is a little more pronounced in the south. Models show there may even be a slight nudge of 850-mb 0C line (good proxy for warm nose on the plan view) northward which could at least stall precipitation transition. As of right now, although a transient period of freezing rain may occur, it does appear that as this happens the cold layer will become sufficiently deep for a transition to sleet. In fact, sleet may be heavy enough and last long enough accumulate across the southern portion of the area. One half inch or more of sleet accumulation seems increasingly likely across portions of southern Indiana. Implications further north where broad warm nose cools to below freezing will be for snow-liquid ratio to be sub-climatology yielding heavy wet snow, with possible heavy riming. Thus, our concern for snow loading. Across the northern portion of our area, SLR should be closer to climatology and with 25+ mph winds, some blowing and drifting of snow is possible. With a colder trend and some potential for a southward shift in QPF, we still feel confident in significant snowfall amounts of near or above 12" in some portions of the area. What we lose in QPF, we`ll gain in increased SLR if the trend continues. This justifies fairly high snow amounts even down into the I-70 corridor, hence the upward trend in the forecast. A final note to our broadcast meteorologists. We always appreciate your critical role in communicating the impacts and threats during these higher impact events. Thanks for your partnership and please never hesitate to reach out to us if we can assist in any way. && .Long Term...(Friday night through Tuesday) Issued at 258 PM EST Tue Feb 1 2022 We will cover the post-event weather into the weekend and early next week only briefly. The main impact appears to be the potential for dangerously cold temperatures over snow pack, particularly Saturday morning when a period of light/calm winds and excellent radiational cooling exists. Sub-zero and locally 10 below or less may occur. There is a weak signal for light precipitation sometime early next week in some medium range deterministic and ensemble guidance, but confidence is low and no mention at this time. Later forecast will clarify this potential. && .Aviation...(00Z TAF Issuance) Issued at 617 PM EST Tue Feb 1 2022 IMPACTS: -Rain will spread NW to SE and start up around issuance time at KLAF and 04z-06z Wednesday KHUF and KIND and finally after 09z at KBMG. -MVFR and worse flying conditions by around 03z at KLAF and by 11z at the other terminals. -Winds will shift from 160-180 degrees to 360-020 degrees after 06z after KLAF and KHUF and not until after 22z at KIND. Wind speeds will be mostly less than 10 knots through 12z and then increasing in speed and become gusty first at KLAF after 12z. DISCUSSION: An inverted low pressure system will draw copious amounts of moisture across the terminals tonight and Wednesday which will allow for solid precipitation starting tonight at KLAF and spreading southeast. As the precip spreads southeast, it will transition over to perhaps freezing rain and sleet from KLAF southeastward before snow becomes predominate. This will also bring deteriorating flying conditions to the terminals. Winds from the south will back to the north Wednesday except perhaps at KBMG. Wind speeds will be generally less than 10 knots but increase after 12z Wednesday with with gusts to 20 plus knots except at KBMG. Marginal non-convective low level wind shear is possible at times late tonight and mainly at KBMG. && .IND WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning from 7 PM Wednesday to 1 AM EST Friday for INZ053>057-060>065-067>072. Winter Storm Warning from 7 AM Wednesday to 1 AM EST Friday for INZ030-035>049-051-052. Winter Storm Warning from 1 AM Wednesday to 1 AM EST Friday for INZ021-028-029-031. && $$ Update...MK Short Term...BRB/White Long Term...BRB Aviation...MK
Area Forecast Discussion
National Weather Service Melbourne FL
941 PM EST Tue Feb 1 2022 .DISCUSSION... Although most of east central FL has been under partly to mostly cloudy skies late this afternoon and evening, no shower activity has been detected by our local Doppler radars. The low level clouds that could produce some minimal rainfall overnight, are moving from east to west and reaching the coastal counties. The HRRR continues to show light showers reaching the coast through the night but these were kept in the forecast for the offshore waters only. Winds will be light from the east. Temperatures after increasing to the lower-mid 70s today, will drop the mid 50s for urban interior and coastal counties and to the upper 40s for rural interior. && .AVIATION... VFR conditions through the night and into Wed. Light winds tonight will increase to 10-15 kt with brief gusts up to 20 kt by mid- morning from the east then veer from the southeast in the afternoon. && .MARINE... As the pressure gradient starts to strengthen tonight, winds will increase to around 18 kt late tonight from the east then veer from the southwest through the day. Therefore, operators of small craft should exercise caution across all the waters except nearshore Volusia. Seas 3-4 ft tonight, building to 4-5 ft offshore on Wednesday. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Negron/Watson