Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/13/20

Area Forecast Discussion
National Weather Service Flagstaff AZ
846 PM MST Wed Feb 12 2020 .SYNOPSIS...Quiet weather will continue through Sunday. Daytime temperatures will warm to above normal values by Saturday. A weather system brings a slight chance of precipitation to the region Sunday night into Monday. Expect cooler temperatures early next week. && .UPDATE... Satellite imagery from this afternoon showed a large portion of snow cover melting in the Little Colorado River Valley. This has led to surface dew points about 10 degrees higher than most of the guidance has this evening. We have updated dew point forecasts following the HRRR model overnight and added some patchy fog for late tonight through mid day Thursday for much of the Little Colorado River Valley. && .PREV DISCUSSION /235 PM MST/...The morning cloud cover over far eastern Arizona dissipated around 10 am, leaving us with sunny skies and light west-northwest flow. Clear skies and calm winds will allow for a chilly night as radiational cooling is maximized. Additionally, remaining snow cover over eastern Arizona will aid in cooling surface temperatures even further. The next notable weather feature will be a dry shortwave set to cross the region Friday night into early Saturday. The only impact from this system is expected to be breezy west to southwest winds on Friday and Saturday. Rising heights will result in warming temperatures over the next few days, with daytime highs reaching 5-10 degrees above normal on Saturday and Sunday. Long range operational and ensemble guidance continues to indicate another trough brushing the state late Sunday into Monday. This system has a bit more moisture to work with, so left in the slight chances for precipitation from the previous forecast. We will continue to monitor the track of this system over the next several days. Temperatures look to cool behind this system early next week, with highs currently forecast to be right around normal for mid-February. && .AVIATION...For the 06Z package...Mainly VFR conditions will prevail through the TAF period. Patchy MVFR due to low clouds and/or fog possible east of a KRQE-KINW-KSOW line through 14Z Thursday. Sfc winds light. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Dry weather and warmer temperatures will continue for the next couple days. Light and variable winds on Thursday will become breezy out of the southwest on Friday. Saturday through Monday...Expect dry and warm weather for much of the weekend. A weather disturbance will bring a slight chance of precipitation and cooler temperatures later Sunday into Monday. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...DL/TPS AVIATION...Peterson FIRE WEATHER...AT For Northern Arizona weather information visit
Area Forecast Discussion
National Weather Service Grand Rapids MI
1017 PM EST Wed Feb 12 2020 LATEST UPDATE... Update .SYNOPSIS... Issued at 330 PM EST Wed Feb 12 2020 - Accumulating snow Tonight-Thursday with Surface Low/Arctic Front - Lake effect snow Thursday night into Friday - Clipper system brings another shot of snow Sat-Sat Night - System for Monday/Tuesday trends a bit cooler/more snow && .UPDATE... Issued at 1015 PM EST Wed Feb 12 2020 The arctic front is crossing Grand Travis Bay as I write this (955 pm). There is a band of heavy snow showers associated with the front. It would seem the front is moving faster than we expected it to. It now seems the arctic front will reach MKG by 2-3 am. It should get to GRR by 4-5 am. That band of heavy snow showers will just sinks south just ahead of the front. I believe our entire CWA will see a 15 minute period of heavy snow with some blowing and drifting snow. What has been curious to watch is where the heaviest snowfall this evening has been. There is frontal trough, enhanced by the core of the upper jet being over it and an upstream shortwave over WI over Muskegon County, Northwest Kent and Southern Newaygo County were 1 to 2 inches of snow has fallen already based on our radar snow accumulation algorithm. It would seem to me by 7am the greatest snowfall will actually end up being in our Lake Shore Counties north of Holland due to the frontal trough and then the arctic front coming through. For now I was thinking to leave our headlines as they area as most of the snow from this system will be during the day Thursday as the upper wave comes through behind the arctic front. UPDATE Issued at 642 PM EST Wed Feb 12 2020 As of 6 pm the snow has made it as far north as Three Rivers. Based on the last few runs of the HRRR and the 18z NAMNest it seems to me snow should reach I-94 by 7 pm and I-96 by 9 pm. Here is the glitch through. All of the recent (since 15z) runs of the HRRR,HRRRX,HRRRdev3, NAM and NAMNest show a break in the snowfall over most of our CWA between 1 am and 5 am. The shortwave associated with the arctic front redevelops the snow and that continues over most of our CWA during the daylight hours of Thursday. Still we get 2 to 3 inches over most of our CWA south and east of a line from Alma to near Grandville by 4 pm Thursday. && .DISCUSSION...(This evening through next Wednesday) Issued at 330 PM EST Wed Feb 12 2020 -- Accumulating snow Tonight-Thursday with Surface Low/Arctic Front The snow totals have trended down a bit from this time yesterday with the ECMWF leading the way on that trend. Totals were never expected to be extremely heavy though with our 2-5 inch forecast from yesterday moving towards 1-4 inches in the current forecast. Most areas will see 1-3 inches of snow the next 24 hours (this evening through Thursday evening), with the highest amounts (isolated 4`s) towards BTL and JXN. The impacts are still expected to be potentially substantial in terms of travel given the temperature plummet late tonight and Thursday morning. Temperatures will drop 10 degrees with in an hour or so with the passage of the Arctic front. In the Grand Rapids metro area for instance, the temperature is forecast to drop from around 32F at 600am to 22F at 800am. That type of drop, along with falling snow at the morning commute could potentially be significant. So, dispute the lack of bigger snow totals, impacts may be the same as an advisory with higher snow amounts. A burst of snow will move into the forecast area from the south this evening after dark and persist into the overnight hours. This snow is associated with the low pressure system moving through the Ohio Valley. Another burst will come on the Arctic front on Thursday. This secondary burst will be on the order of a half inch to possibly two inches. This secondary burst is the one that coincides with the temperature plunge. Bottom line, we are expecting impacted travel in the current advisory area and potentially even further north across Central Lower Michigan. We considered expanding the current advisory through Central Lower, but held off at this point given lower totals and shorter duration of the heavier snow. Thursday morning will be the main time frame of concern across Central Lower. -- Lake effect snow Thursday night into Friday The lake effect snow still looks impactful and we will likely transition into a Winter Weather Advisory towards the lake as we get closer to that event. Solid lift remains in BUFKIT overviews in a DGZ that remains off the ground. Moisture depth is limited, but snowfall will continue towards the lake Thursday night and Friday. Expect small flake size, snow totals in the 2-4 inch range and potentially bigger impacts given the cold temperatures on road mitigation efforts. Salt will not be effect given air temps in the single digits and low teens. -- Clipper system brings another shot of snow Sat-Sat Night Quick hitting snow event is still in the forecast for Saturday afternoon and Saturday night. It looks like we could see a quick 1-3 inch snow with a lake enhancement boost. The flow will be southwest so Newaygo County may be the spot that see the most snow. -- System for Monday/Tuesday trends a bit cooler/more snow The early next week system has trended a bit further south so we may see a bit more snow on the lead edge and on the back side of the low as well. Models still have disparity, so we have time to lock in on a solution. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 642 PM EST Wed Feb 12 2020 I based the TAFs tonight on looking at several runs of the HRRR,HRRRX,HRRRdev3, NAM and NAMNest and looked at radar loops and in so doing tried my best to figure out when the snow would move from our I-94 TAF sites (01z ) to I-96 (03z). I do not think cigs will become IFR once the snow starts, it may take an hour or two for the cigs to lower that much since there is still a fair amount of low level dry air to overcome. Between 03z and 06z all TAF sites should be IFR in snow. As stated in the update section the HI RES models all show a break in snow pattern between 07z and 11z (more or less). Maybe Jackson would be least impacted by that break in the snow pattern. None the less since all of the Hi-Res model runs have shown this since mid morning, and it make sense given the meteorology of the situation, I did feature a break in the snowfall in most of our TAF sites. I did not totally stop the snow but brought the visibility up to either VFR (MKG) or MVFR (GRR, AZO , BTL, LAN) during that time frame. Once the arctic front comes through expect gusty winds, snow and blowing snow at all TAF sites. At any one location the lower conditions with the front will last around 3 hours. I expect the snow to start to end by late afternoon. Lake effect snow bands will start impacting MKG by late afternoon but will not reach the GRR or AZO taf sites will well after midnight. Do expect moderate to heavy icing in the clouds tonight and light to moderate icing in the clouds Thursday. As the arctic front pushes south of the area by midday expect only light icing in the clouds. && .MARINE... Issued at 330 PM EST Wed Feb 12 2020 Small Craft Advisory (SCA) remains in place north of Holland for a southwest flow event that is ongoing. Big Sable Point has been gusting to 25 to 30 knots all afternoon and the Muskegon GLERL cam that looks southwest has plenty of white water (waves) ongoing. The SCA looks good. Earlier today we upgraded to a Gale Warning for late tonight into Thursday. There is a core of wind seen in the BUFKIT overviews at mid lake that should be indicative of the winds over much of the water. We should see gales from 400am through 100pm which is the core of the wind. The incoming waves on the South Haven GLERL cam should be solid with 6 to 9 footers expected. Points to the south will have higher waves with 10+ foot waves expected on the south end of the lake. && .HYDROLOGY... Issued at 330 PM EST Wed Feb 12 2020 Despite the lack of rainfall/runoff lately, river levels continue to fall extremely slowly, due to the high groundwater levels and saturated soils. Maple River at Maple Rapids is still near bankfull, but should finally drop below in the next day or so. Meanwhile, we are still expecting a fairly brief but intense blast of cold air to move into Lower Michigan tomorrow (Thursday) and continue through Saturday morning. This will start up the ice machine on our rivers, and also creates the possibility of a few ice jams forming in the area. Because it`ll be warming up quickly by Saturday, the risk for significant jams will be lower than during typical cold snaps, but the common trouble spots could see water level increases as the ice piles in this weekend. These spots include the Muskegon River between Big Rapids and Rogers Dam, the tributaries of the Grand River like the Looking Glass and Maple River, as well as parts of the Grand River itself near Robinson Township. In addition, the Kalamazoo River will also be seeing new ice formation, so the area near Comstock will have the possibility of renewed ice jam formation as well. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 7 PM EST Thursday for MIZ056>059- 064>067-071>074. LM...Small Craft Advisory until 1 AM EST Thursday for LMZ846>849. Gale Warning from 1 AM to 1 PM EST Thursday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...Duke DISCUSSION...Duke AVIATION...WDM HYDROLOGY...AMD MARINE...Duke
Area Forecast Discussion
National Weather Service Wichita KS
920 PM CST Wed Feb 12 2020 .UPDATE... Issued at 918 PM CST Wed Feb 12 2020 Last snow bands associated with the main deformation zone continues to make slow progress to the east this evening. Now mainly located east of the KS Turnpike. So will nix another row of counties from the winter weather advisory for areas west of the Turnpike. Current eastward progression of the snow suggests that the rest of the winter weather advisory will be allowed to expire as planned at midnight CST. A strong cold front is currently working its way south with gusty north winds already moving into Newton, McPherson and points north. As the cold front moves in, temperatures are falling rapidly, with portions of central KS already falling into the low 20s. Temperatures are already in the low teens across southern Neb. there is some drier air moving south, with will help evaporate or sublimate some of the moisture on the roads, but could still see some patchy slick spots develop from "flash freezing" by early Thu morning. This arctic air will continue to plunge south across the area late this evening and overnight with expected lows falling into the single digits! Made some tweaks colder, to forecast mins, as model certainty suggests lots of clustering of model temps closer to the RAP and HRR min temps, which would push lows a few degrees colder. With the expected winds overnight, even a few degrees colder will be critical for expected wind chill values for areas near the Wichita metro and points northeast towards EMP. Could see wind chill values of minus 11 to minus 13. Ketcham && .SHORT TERM...(This evening through Friday night) Issued at 305 PM CST Wed Feb 12 2020 Highlights: 1) Snow/rain will end by midnight 2) Flash freeze of residual water and slush tonight 3) Below zero wind chills on Thursday morning 4) Single digit wind chills Friday morning Headline: Winter Weather Advisory thru midnight A strong cold front will push southward across the region tonight with much colder air in its wake. The snow/rain mix will continue across the area into the evening with some light additional snow accumulations possible. Meanwhile a second band of precipitation looks to develop along the surface front and race southeast across the region due to strong forcing. The main concern will be the surge of much colder air and gusty north winds(around 40mph) spreading southward overnight. This will cause all wet roads and surfaces to flash freeze thus resulting in slick conditions for any untreated roadways. Another concern will be sub-zero wind chills overspreading the area for late tonight and daybreak on Thursday. -Jakub After a chilly start to Thursday with surface high pressure over the area, temperatures will rise only into the upper teens to mid 20s. Some models suggest even lower temperatures are within the realm of possibility which could occur with the snow cover from today. Friday morning is going to start out cool (not as cold as Thursday morning) with wind chills in the single digits. Despite temperatures rising to around 40 degrees during the day, breezy winds should keep wind chills below freezing throughout the day as mentioned in the previous discussion. .LONG TERM...(Saturday through Wednesday) Issued at 305 PM CST Wed Feb 12 2020 Highlights: 1) Warm up (back to 50s) Saturday to Monday 2) Slight chances of precip (rain/snow) Monday to Tuesday A weak wave is expected to move through on Saturday, but minimal impacts would occur other than a wind shift. After the cool second half to the week, there will be a stark contrast for Saturday to Monday as high temperatures are forecast to be in the 50s with the lower 60s anticipated along the Kansas/Oklahoma border on Monday. Outdoor activities should flourish. Another trough should move across at the start of next week. Discrepancies remain in the model tracks of this system. These differences as well as the changes in the track have resulted in modifications to the chances for precipitation. There are only slight chances in there at the moment. The precipitation type at this point will be rain, rain/snow and snow. A relative cool down is in store for Tuesday and next Wednesday with temperatures falling to the 40s. Stay tuned for changes to the forecast. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 550 PM CST Wed Feb 12 2020 Lingering light snow will lead to continued IFR conditions for most of the south central and southeast KS tafs for a few more hours. Will also carry some MVFR vsbys for the -SN or VCSH with the snow for the KICT, KHUT and KCNU taf sites. Most of the low cigs and most of the light snow will end early this evening, and be scoured out, as a sharp cold front will push south across the forecast early this evening. This will increase winds to 20 to 35 kts for most of the late evening and overnight hours. As the cold front moves in, the sharp front with drier air will scour out most of the low clouds with VFR conditions returning to the area. Lots of new snow cover across southern KS, but the wet slushy nature of the snow will keep blowing snow chances low to near zero. Ketcham && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 7 23 12 38 / 50 10 0 0 Hutchinson 6 22 11 37 / 20 10 0 0 Newton 5 21 11 35 / 50 0 0 0 ElDorado 6 21 9 37 / 60 0 0 0 Winfield-KWLD 10 25 13 40 / 50 0 0 0 Russell 8 23 13 41 / 20 10 0 0 Great Bend 8 23 13 42 / 20 10 0 0 Salina 6 22 11 36 / 50 10 0 0 McPherson 5 22 10 35 / 30 10 0 0 Coffeyville 14 25 12 42 / 70 0 0 0 Chanute 10 21 9 38 / 80 0 0 0 Iola 9 20 8 38 / 80 0 0 0 Parsons-KPPF 12 23 10 40 / 80 0 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until midnight CST tonight for KSZ053- 069>072-093>096-098-099. && $$ UPDATE...Ketcham SHORT TERM...CDJ/VJP LONG TERM...Juanita AVIATION...Ketcham
Area Forecast Discussion
National Weather Service Northern Indiana
910 PM EST Wed Feb 12 2020 .SYNOPSIS... Issued at 252 PM EST Wed Feb 12 2020 Accumulating snow will spread into the region from south to north late this afternoon through the evening hours. The snow will be heaviest early tonight...gradually tapering off Thursday morning. Lake effect snow follows the system snow and continues into early Friday. Much colder air follows Thursday and Friday. Temperatures will dip into the single digits Thursday night and struggle through the teens on Friday. The cold air will be shortlived with temperatures back to near normal Saturday into next week. && .UPDATE... Issued at 910 PM EST Wed Feb 12 2020 Overall forecast largely on track with just some minor edits this evening. Broad WAA/isentropic ascent in right entrance region of potent upper jet streak supporting widespread light-moderate snow. Some minor banding noted on radar imagery just upstream and in our far southeast where slightly better moisture/instability reside but overall just a widespread steady snow. Flake size has been small at most locations and is a limiting factor for more efficient accumulation. This forcing will be very brief as upper jet quickly shifts east and anticipate a lull in steady snow around 06Z but additional CVA arrives around 12Z and will support another slight uptick in snowfall rates/coverage. There is still some potential for freezing drizzle between the two rounds but the window is short and most forecast soundings still indicate a good chance of ice nucleation through the overnight. Kept freezing drizzle mention in the forecast but limited it both temporally and spatially (along/south of US-224). Net result in latest update was to lower amounts slightly in our north and raise them in our south where less melting has already supported 3-4 inches. No upgrades planned in the south as bulk of the event will be over in the next few hours and additional amounts around 12Z are expected to be light. Steady synoptic snow still expected to wind down shortly after 12Z but lake effect will ramp up through the day as colder air arrives. No changes to headlines planned this evening but extensions (or new advisories) will likely be needed for our N/NW zones with lake effect snow continuing into Thu night. && .SHORT TERM...(This Evening into Thursday Morning) Issued at 252 PM EST Wed Feb 12 2020 A broad trough across the Rockies forces a low pressure system to form in conjunction with moisture along the western Gulf of Mexico. This traverses northeast along a track through the Ohio River valley southeast of our forecast area. High pressure across the area today continues to push east during the day today. Very cold air still located in southwest Canada is associated with 1035-1040 mb high pressure, but air cold enough for snow will still be located over the Great Lakes region with low level temps a couple degrees below 0C. This should allow for around 10:1-12:1 snow ratios. Dynamics-wise, upper level support from a phased jet begin moving into the area right around the onset time of snow and continue a few hours after midnight. Also good location of -EPV over f-gen forcing is showing up especially as the deformation zone works in from west to east not too far after midnight. There is also some indication from the NAM that the -EPV/f-gen forcing zone would be Soundings also indicate a near isothermal layer up to around 600 mb below 0C allowing for the possibility of larger aggregates moving in during a time frame on either side of midnight. All of these would work to create a time period of moderate to heavy snow across the area this evening up until an hour or 2 after midnight. Saturation to start snowing is a question with this setup. RAP time sections for FWA and SBN indicate saturation between to 3 and 5pm. There is some indication that snow could start out at a moderate intensity with HREF prob of >1"/hr showing 10-30% percentages from 5pm to 10pm as the snow gets started. RAP time sections indicate a favorable cross hair situation with a relatively moist DGZ and highest omega in the DGZ. After about 8pm, some indication that freezing drizzle could work in south of US-24 exists with a dry DGZ showing up in soundings and cross sections and continuing until around midnight as a midlevel dry slot works in. This could cut snow totals down farther than what we already have in there in that area. && .LONG TERM...(Rest of Thursday through Next Wednesday) Issued at 252 PM EST Wed Feb 12 2020 Upper jet passes by the area by 12z Thursday and cold air advection takes over allowing for a time frame of lake effect snow. Northwest trajectories start after 12z Thursday when a cold front moves southeast away from the lake. Inversion heights rise up to around 850 mb, but with good low level convergence and limited shear to break up dendrites. Some potential exists for lake effect extending away from the lake down towards US-24 during the day Thursday with some instability to work with behind the cold front, but weakly gusty winds could limit the distance away from the lake it travels. All told, continue to expect a 1 to 2, localized 3 inch snowfall total with the greatest totals closer to the lake mainly northwest of a Starke county to Cass county, MI line. High pressure noses its way into the region swiveling trajectories around to the west and shutting off lake effect for much of the region Friday morning. A cold airmass that is one of the top 5 coldest for this season arrives Friday morning with the entrance of the high pressure system. Lows Friday morning drop to single digits away from lake effect clouds to low teens underneath the lake effect clouds. Highs Friday will only be in the mid teens to near 20 degrees within some sunshine especially in areas southwest of a LaPorte to Portland line. However, it`s a quick rebound to seasonable temperatures for the weekend. These temperatures are what a clipper system has to work with as it brings a chance for snow Saturday night/early Sunday. With those temperatures being so marginal, I can`t rule out that snow mixing with rain for a portion of this event. Another chance for precipitation comes in early next week that would primarily be a rain event. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 647 PM EST Wed Feb 12 2020 Moderate snow will continue through the late evening as strong WAA/isentropic ascent wing moves through the area. 300-400ft ceilings and 1/2SM visibilities will be possible at times over the next few hours but held slightly higher for prevailing conditions with these TAFs based on upstream obs and concensus of latest numerical guidance. Parent upper jet streak exits fast and anticipate a break in moderate snow around 05-08Z before primary trough axis and embedded shortwave approach. This will bring another period of light-moderate snow around 10-12Z (mainly at KFWA). Some brief freezing drizzle is also possible at KFWA in the 07-10Z period but confidence is too low for inclusion based on latest forecast soundings. Lake effect snow showers then expected on Thursday with variable but steadily improving conditions through the day. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Winter Weather Advisory until 1 PM EST /noon CST/ Thursday for INZ003>009-012>018-020-022>027-032>034. Lakeshore Flood Warning from 6 AM Thursday to midnight CST Thursday night for INZ003. MI...Winter Weather Advisory until 1 PM EST Thursday for MIZ077>081. Lakeshore Flood Warning from 7 AM Thursday to 1 AM EST Friday for MIZ077. OH...Winter Weather Advisory until 1 PM EST Thursday for OHZ001-002- 004-005-015-016-024-025. LM...Gale Warning from 4 AM to 4 PM EST Thursday for LMZ043-046. && $$ UPDATE...AGD SYNOPSIS...Roller SHORT TERM...Roller LONG TERM...Roller AVIATION...AGD Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service New Orleans LA
557 PM CST Wed Feb 12 2020 .AVIATION... Widespread MVFR and IFR conditions will persist until late tonight into early tomorrow for terminals west to east. Generally a few showers here and there are expected out ahead and along the approaching cold front. Ceilings are still generally low, winds have gusted up into the 20 knots range, and fog may set in again at the terminals before the cold frontal passage can flush it out. Once it has passed, conditions should steadily improve. -BL && .PREV DISCUSSION... /issued 324 PM CST Wed Feb 12 2020/ DISCUSSION... Much to discuss in the next 24 hours, so lets dive right into it. Latest satellite/radar observations continue to illustrate a few pre-frontal, shallow showers developing across the area, generally along the northshore and west of I-59. CAM`s depicted this possibility nicely over the previous 24-36 hours. However, so far these still lack the vertical depth necessary for sustainable updrafts. HRRR soundings paint a clear picture to what is going on. As discussed in the morning update, there is a lot of dry air in the H7-H5 layer, and surface temperatures have not warmed up just enough yet to allow for ricing parcels to surpass this layer. KLIX radar trends actually are scanning the tops of these cells right around 12-14kft AGL, right at the base of this inversion in model soundings. This will change though, as intervals of sunshine will continue to destabilize the pre-frontal environment. Temperatures will continue to rise which will allow for ricing parcels (both SB and in the mixed layer) to surpass the inversion, and grow beyond to the EL and become stronger. The current broken line along I-55 also appears to be along a mesoscale boundary between convergent wind flow (BTR 190 degrees/HDC 170 degrees) and will continue to drift slowly to the northeast through the afternoon. Once larger scale destabilization continues, more isolated cells may develop later this afternoon and evening. Pre-storm environment continues to indicate supportive shear conditions, which means any stronger storm may try to rotate with an isolated tornado and damaging winds the main threats with these. Once this first round exits later around 4-5PM, next focus will be along the actual front. Look for a broken line of weak cells to press into our far western CWA roughly around 6PM. As the surface low to our northwest continues to eject northeast away from our area, so will the better atmospheric dynamics and shear. Models are confident on surface winds shifting more from the SSW to SW, limiting directional shear in the vertical out ahead of the approaching broken line of showers/storms. This will largely limit the overall severe risk, regardless of impressive speed shear (Bulk shear around 55-65 knots).However, a few strong wind gusts cannot be ruled out, especially along any smaller bowing segments. As the line continues east after sunset, any lingering stronger storms will likely diminish due to lack of supportive instability with a line of showers working its way west of I-55 to the MS coastline by early Thursday. Still looking like a cloudy day on Thursday with lingering post-frontal stratocumulus. NAM shows a weak, stretched area of vorticity riding along the progressive SW to NE flow aloft which will try to deliver some light drizzle/showers during the day, with better chances east of I-55 making Thursday a yucky, gray cool and wet day. However, Friday will promise sunshine with continued on the cool side. Still looking like we slowly warm up through the weekend, with the next, weak low-amplitude trough swinging across the area on Sunday. Might be just enough moisture to allow for some scattered showers, but will not amount to much in the way of heavy rain. Next system beyond this one still looks to be around the middle of next week, and remains not overly impressive in the form of delivering any heavy rain or severe weather, but beyond that is looking quite chilly again. Welcome to late winter along the Gulf coast. KLG MARINE... Latest observations indicate improving conditions across many marine zones, and have canceled all remaining Marine Dense Fog Advisories in effect. However, visible satellite imagery does show some patchy marine fog right offshore the southern MS coastline, but does not appear overly dense and is rather localized. HRRR/CONSShort guidance supports re-development of marine fog later this evening, and have went ahead with marine Dense Fog highlights beginning at 6PM CST in these areas until a cold front sweeps it out early Thursday morning. A few strong wind gusts may be possible along this front as it crosses from west to east through all marine zones tonight and early tomorrow, but severe weather appears unlikely. Also, gusty winds in Lake Pontchartrain and Maurepas prompted exercise caution headlines from noon to 6PM today. Winds should steadily lower after sunset. After the front passes Thursday, northwesterly winds will persist. Still looking like borderline Small Craft Advisory conditions beginning early Friday through Friday night. Regardless of any headlines, gusty northeasterly winds can be expected, along with increased waves/seas. Conditions steadily calm going into the weekend with no additional hazardous weather expected. KLG AVIATION... UPDATED 1821Z... Advection fog and low ceilings have been slow to dissipate along the coastal areas. KGPT still has visibility around 1sm and may not improve much until the cold front moves through tomorrow morning. Wind have risen to around 10 knots and increased boundary layer mixing lifts ceilings to around 1500 to 2000 feet for the afternoon hours. However, ceilings should lower back to around 500 feet in the evening hours tomorrow as southerly winds persist. Scattered showers have been spreading across the region with thunder possible within an hour or so. A band of convection will also begin to impact most terminals between 00z and 06z. This convection will be associated with a frontal passage. At KMSY, a wind shift to the west is expected by 10z as the convective band and associated cold front pushes to the east. Gradual improving conditions after fropa tonight. DECISION SUPPORT... DSS code: Blue. Deployed: None. Activation: None. Activities: Marine Dense Fog Advisory - MS Sound Day 1 Marginal Risk for Severe Weather /Excessive Rainfall Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event; Marginal risk severe or excessive rain. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support for slight risk severe or excessive rain. Orange = High Impacts; Enhanced risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate to high risk of severe and/or excessive rainfall, or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 52 58 37 56 / 80 20 0 0 BTR 52 57 38 56 / 70 20 0 0 ASD 54 61 39 59 / 100 40 10 0 MSY 56 60 44 58 / 100 30 10 0 GPT 56 62 41 57 / 100 40 10 0 PQL 57 65 38 59 / 90 60 20 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...Dense Fog Advisory until 6 AM CST Thursday for GMZ532-534-536- 538-557. MS...None. GM...Dense Fog Advisory until 6 AM CST Thursday for GMZ534-536-538- 557. && $$
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1012 PM EST Wed Feb 12 2020 .SYNOPSIS... The cold front will lift back north as a warm front tonight, followed by a cold front that will cross the area Thursday Night into early Friday. Cooler high pressure will move in late week into the weekend. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... As of 1005 PM Wed...Warm front is now just north of Cape Hatteras with temperatures reaching into the upper 60s and increasing southeasterly winds. This is the only land area in our CWA that is in the warm sector, with all other areas still stuck in the 50s. HRRR has trended towards a slower frontal passage and nudged the overall forecast in this direction, favoring lighter winds and lower Td/Ts. The overall forecast picture has not changed with the front expected to lift north ushering a warmer airmass over the region overnight. Prev disc...The latest analysis is showing the cold front that pushed through early this morning is to the south of the area as weak high pressure ridges down from the north, while a low pressure system is developing over the lower Mississippi Valley this afternoon. The sfc high will gradually slide off the Mid- Atlantic coast as the low lifts northeast overnight into the Mid-Atlantic region and prompting the cold front to the south, to lift as a warm front this evening, which can enhance shower activity along our coastal counties. Most of the Hi-Res models are showing most of the light showers to be east of Highway 17. Temps will climb through the night due to strong WAA, with lows likely occurring shortly after sunset. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/... As of 305 PM Wed... The aforementioned low pressure system will be located over the Mid- Atlantic region with it`s associated strong cold front approaching the area from the west. Models are showing light showers to continue along the immediate coast during the morning with possible isolated showers to approach from the west and effecting the coastal plains during the morning. The bulk of the rain will be early afternoon as models continue to show an enhanced band of showers crossing the CWA with the heaviest rain, closer to the coast by tomorrow evening. Models continue to show a decent low-level jet and weak CAPE values; while SPC has most of the area in a Marginal Threat of severe weather tomorrow as a few strong to isolated severe storms may occur, but think the overall severe possibility will be fairly limited. Near record-high temperatures will be possible, especially inland due to the warm advection ahead of the front. Expect highs in the upper 70s to around 80 degrees inland and low/mid 70s along the coast. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... As of 335 PM Wednesday...A strong cold front will cross the region Thursday evening and Thursday night, followed by a brief cold snap. A quick return to milder weather is expected by Sunday into early next week. Thursday Night through Saturday Night...A cold front will push through Eastern NC late Thursday evening through Thursday night. There continues to be a small chance for thunderstorms during the evening hours ahead of or associated with a line of convection expected to cross eastern NC during the evening/early overnight hours. If any storms were to become severe, damaging wind gusts would be the main threat. High pressure centered over the Midwest will build in from the north on Friday and Saturday, then shift offshore of the Mid- Atlantic region Saturday night. Max temps fall into the 50s Friday and upper 40s inland to near 50 along the coast for Saturday. Friday night temperatures will be the coldest of the long term with lows in the upper 20s inland to mid 30s along the coast. Sunday through Monday...Precip forecast for Sunday is a bit tricky, though guidance continues to suggest a weak inverted trough forming along the NC/SC coast, while a modest shortwave crosses the region from the west, helping support shower production on a larger scale by late Sunday afternoon. Continued slight chance PoPs for the afternoon with low confidence. Temps begin to moderate into the 50s Sunday. High pressure builds in from the north/east Monday allowing for return flow to build temps/dew points Monday, with forecast max temps in the mid 60s south to lower 60s north, roughly 10 degrees above climatology for mid February. Tuesday into Wednesday...An upper trough will dig from the central MS valley area northeast into southeastern Canada. A strong surface low will develop over the Ohio River Valley on Tuesday, with strong high pressure offshore of the East Coast. The surface low will track northeast into New England Tuesday night into Wednesday, dragging a cold front into the region Tuesday night and offshore of NC by Wednesday. Continued chance PoPs for Tuesday into Wednesday, with temps well above climo, lower 70s both days. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Short Term /through 06Z Thursday/... As of 730 PM Wed...Predominantly MVFR conditions this evening across the sites, but expect conditions to deteriorate as warm front currently located along the NC/SC state line is forecast to lift north in the next few hours. Expect more predominant IFR conditions to begin late this evening with increasing low-level moisture. Some patchy fog is possible immediately with the frontal passage as winds remain light, but should quickly lift to low stratus as southerly winds increase after 06z. Ceilings should rise back to MVFR just before sunrise with increased mixing and remain so for much of the day Thursday, with the exception of locally lower visibilities/cigs with showers and thunderstorms associated with a passing cold front during the afternoon. Additionally, strong southwesterly winds are expected ahead of the front with a few gusts up to 30 knots not out of the question in the coastal plain. Long Term /Thursday Night Through Monday/... As of 335 PM Wednesday...A strong cold front will produce widespread showers and isolated tstms into Thursday night with periods of sub-VFR conditions likely. A return to VFR conditions is expected for Fri/Sat as TAF sites remain under the influence of dry high pressure. A few afternoon showers, associated with a strong mid-level shortwave, may briefly reduce ceilings and vsbys Sunday afternoon. High pressure offshore will build back into the region on Monday. && .MARINE... Short Term /through Tonight/... As of 735 PM Wed...Per hi-res ECMWF guidance and latest HRRR runs, added the Ablemarle Sound and Alligator River under SCAs early this morning to the afternoon. Otherwise current marine forecast remains on track - sea fog is slowly making its way along the SC coast and should make it to our southern coast in a few hours. Prev disc... The latest buoy observations are showing ENE winds 10-20 knots and seas 3-5 ft. A warm front will lift north across the waters this evening, with winds becoming SE/S 15-25 knots and seas building above 6 ft late tonight. SCA will go into effect late tonight for all the coastal waters, except the central waters where Gale Warning. SCA will also in effect for the Pamlico, Croatan, and Roanoke Sound, while holding off for the Albemarle Sound and Alligator Rvr. By tomorrow, winds will peak 15-25 knots with gusts up to 30-35 knots and seas building to as high as 9-10 feet, especially central waters. Sea fog is possible beginning late tonight as SW flow develops and low level moisture values surge. However, coverage may be limited by persistent breezy flow. Long Term /Thursday Night through Monday/... As of 340 PM Wednesday...A strong cold front will cross the Eastern NC waters late Thursday night into Friday morning. Behind the front, N winds are expected at 15-20 knots with gusts to 25 knots. Winds diminish a bit Friday, but another good surge expected Friday night with gusts up to 30 knots again possible. Rough seas continue through midday Saturday, before subsiding. As high pressure moves offshore, SW winds develop Sunday at mostly 10-20 knots, with seas of 2-4 feet. && .CLIMATE... Record High temps for 02/13 (Thursday) LOCATION TEMP/YEAR New Bern 83/2017 (KEWN/ASOS) Cape Hatteras 70/2019 (KHSE/ASOS) Greenville 83/1932 (Coop - Not KPGV AWOS) Morehead City 74/1984 (Coop - Not KMRH ASOS) Kinston 81/1965 (Coop - Not KISO AWOS) && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...Small Craft Advisory from 4 AM to 7 PM EST Thursday for AMZ135. Small Craft Advisory from 4 AM to 3 PM EST Thursday for AMZ131- 230-231. Gale Warning from 5 AM to 7 PM EST Thursday for AMZ152-154. Small Craft Advisory until 7 AM EST Friday for AMZ156-158. Small Craft Advisory from 4 AM Thursday to 1 AM EST Friday for AMZ150. && $$ SYNOPSIS...MHX NEAR TERM...BM/MS SHORT TERM...BM LONG TERM...CTC AVIATION...CTC/MS/ML MARINE...CTC/BM/MS CLIMATE...MHX
National Weather Service Morristown TN
715 PM EST Wed Feb 12 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... A quick update will be issued to account for the faster speed of the convective line that has been moving across N AL and Middle TN. Wind damage reports have been numerous with this line, with some rotation signatures embedded in it. While it is expected to weaken as it moves east, the southern portions of our area closest to a boundary across N GA will have the greatest threat of severe storms/tornadoes over the next few hours. DGS && .AVIATION... 00Z TAF DISCUSSION. A narrow convective line will be passing through the area in the next few hours, bringing IFR conditions with the heaviest rainfall and a chance of TS at CHA. Gusty winds of 30-40 kts can also be expected. Ahead of the line, LLWS will be present at all sites. Behind the line, LLWS should end and lighter rain should allow vis to rise to MVFR, but with cigs remaining IFR. A wind shift to westerly will occur toward morning with a frontal passage, with cigs lifting to MVFR - potentially VFR at CHA - during the day. DGS && .PREV DISCUSSION... /ISSUED 339 PM EST Wed Feb 12 2020/ SHORT TERM (Tonight and Thursday)... Current satellite imagery and surface observations show a warm front across north GA and AL with dewpoints in the 60s within the warm sector. North of the front across our area, dew points remain in the 40s with a more stable airmass and an inversion near the 850mb level. Downslope flow is evident on visible satellite imagery across portions of Blount, Sevier, Cocke, Greene, Unicoi, and Carter Counties with breaks in low-level cloud cover. As the low-level jet strengthens in response to the 180kt upper jet streak across the Great Lakes and Ohio Valley, warm and moist boundary layer air will be transported northward overnight. For this reason, temperatures will rise overnight ahead of the frontal boundary and line of convection. As dew points approach the upper 50s and lower 60s across northern AL/GA and southern TN, RAP guidance shows MLCAPE near 200 J/Kg across the southern counties of Marion, Sequatchie, Hamilton, and Bradley. The weak instability will greatly limit the severe potential, but with at least marginal surface based instability possible and low-level shear being very strong, there will be at least a chance of damaging wind gusts and a low chance of a brief QLCS tornado with the line of thunderstorms across the southern Cumberland Plateau and southern Tennessee Valley near the AL/GA borders in this high shear / low CAPE environment. The strong LLJ will result in very strong winds across the mountains and foothills tonight. With S/SSW winds of 70kt and the pressure gradient across the mountains, this will be a favorable setup for mountain wave high winds. Will increase max winds in the High Wind Warning to around 80mph because of the anomalously strong LLJ magnitude. Will continue the Flash Flood Watch, but believe the overall flash flood threat to be low and isolated. With PW values of up to 1.4 inches, this will favor heavy rainfall. However, the quick forward motion of thunderstorms tonight will limit overall rainfall amounts and limit flooding issues to regions of locally heavy downpours. Expect the Flash Flood Watch can be cancelled by 12z as the line of rain and embedded thunderstorms should have exited the area. In the wake of the cold front, winds shift to the WNW/NW on Thursday with drier and cooler air advecting into the region. Cloud cover will slowly decrease with some clearing by the afternoon across downslope regions of the valley downstream of the plateau. With colder air across the higher elevations, could end the day with a few flurries or light snow showers across the highest elevations of the mountains, generally at or above 4000 feet. Amounts would be light and limited to a few tenths of an inch or less. JB LONG TERM (Thursday night through Wednesday)... A reinforcing shot of cold air will surge into the area Thursday night and early Friday. There may be a few sprinkles or flurries around mainly northeast Thursday night, then Friday will be cold with high temperatures well below seasonal normals despite increasing sunshine. A short wave ridge aloft and surface high pressure will keep things dry for the first part of the weekend with moderating temperatures. By Sunday and beyond forecast uncertainty is higher. The models indicate there may be some weak short wave energy moving across the area at times during the Sunday through Monday period, but differ on strength/timing/placement. Will have more clouds and carry low PoPs for Sunday, Sunday night, and Monday, but it is doubtful that we will see precipitation in our area all three periods and if precipitation does occur it will likely be light. By Tuesday the next frontal system will be moving in, with better chances for precipitation for the end of the long term period. Temperatures look warm enough for this to be a mainly rain event. LW && .MRX WATCHES/WARNINGS/ADVISORIES... NC...Flash Flood Watch until 7 AM EST Thursday for Cherokee-Clay. TN...Flash Flood Watch until 7 AM EST /6 AM CST/ Thursday for Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell- Claiborne-East Polk-Grainger-Hamilton-Hancock-Knox-Loudon- Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount- Northwest Monroe-Rhea-Roane-Scott-Sequatchie-Sevier Smoky Mountains-Southeast Monroe-Union-West Polk. High Wind Warning until 7 AM EST Thursday for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky Mountains-Southeast Carter-Southeast Greene-Southeast Monroe-Unicoi. VA...Flash Flood Watch until 7 AM EST Thursday for Lee. && $$
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
706 PM EST Wed Feb 12 2020 .UPDATE... Latest RAP model has mid/upper level ridging...centered near the Bahamas...beginning to slide eastward later tonight and Thu as a long wave trough...currently from the Upper Midwest to the southern high plains...pivots into the Deep South during Thu. Atlantic high pressure across FL to the Gulf of Mexico pulls away to the east as a cold front...accompanying the long wave trough... moves into north FL and southwestward across the Gulf late Thu. Deep southerly flow will provide adequate moisture for patchy to areas of fog to form under some cloudiness later tonight and continue into mid Thu morning. The approaching front and long wave trough will provide additional moisture and support for showers in the slight chance to chance range. These will impact Levy County in the afternoon then spread south to around Tampa Bay late afternoon or early evening. && .AVIATION... 13/00Z TAFs. Prevailing VFR gives way to MVFR BTWN 06Z and 19Z with TEMPO IFR 10-14Z...mainly for CIGS although there will be some patchy BR. Light S winds become SW at 11-15KT AFT 18Z. && .MARINE... Patchy to possibly dense sea fog will continue to impact the waters for the next 24 hours or so. Then a front pushing in will bring showers followed by slightly drier air on northwest flow. This will help scour out the fog but increase winds and seas into the caution to advisory range during Fri. Relaxed high pressure behind the front builds in for the weekend with winds veering and diminishing. && .Preliminary Point Temps/PoPs... TPA 67 81 65 74 / 0 30 30 20 FMY 68 83 67 79 / 0 10 0 10 GIF 67 86 66 76 / 0 0 10 30 SRQ 67 82 66 76 / 0 0 20 20 BKV 64 84 61 74 / 0 30 30 20 SPG 67 81 65 74 / 0 30 30 30 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...None. Gulf waters...None. && $$ UPDATE/AVIATION/MARINE...09/Rude UPPER AIR...04/Sobien DECISION SUPPORT...42/Norman