Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/27/17

Area Forecast Discussion
National Weather Service Bismarck ND
933 PM CDT Sun Mar 26 2017 .UPDATE... Issued at 933 PM CDT Sun Mar 26 2017 A slight increase in POPs for the far north central was the only adjustment made to the forecast. Chances for isolated showers should dwindle down within an hour. UPDATE Issued at 644 PM CDT Sun Mar 26 2017 Based on radar trends and current HiRes models, a slight chance for rain was extended to 02Z. Sky cover was also adjusted/pulled back to reflect current observations. Otherwise, current obs were blended into the forecast and no other changes were made. && .SHORT TERM...(This evening through Monday) Issued at 237 PM CDT Sun Mar 26 2017 The main challenges for the short term will be precipitation chances across the west this afternoon and overnight fog tonight and into Monday morning. This afternoon, a CU field had developed over much of western and parts of central North Dakota. Very steep low level lapse rates were located over the western third of the state, with some modest MUCAPE (~250 J/kg) over the northwest. A few light radar echoes have been pulsing on radar, so the thought is that isolated to scattered convective showers will develop through the afternoon. While a lightning strike or two is not out of the question, confidence is too low to put thunder in the forecast at this time. The latest runs of the HRRR and other CAMs all tend to agree with this afternoon convective activity. As the sun goes down, any lingering showers should begin to dissipate. Overnight we are looking at favorable conditions for fog again over the east, especially the James River Valley. Gradually clearing skies, high soil/surface moisture, and very light winds should aid in the development of areas of fog over the James River Valley, with patchy fog possible further west and north. .LONG TERM...(Monday night through Sunday) Issued at 237 PM CDT Sun Mar 26 2017 The longer term features more of the same, a generally progressive pattern with periodic chances of light precipitation. The best chance for precipitation will likely be Tuesday night and into Wednesday. The ECMWF had been the most bullish about precip amounts, but even its latest 12z solution has settled down quite a bit. Other waves bringing chances for light precipitation will approach the area by the end of the work week and the weekend, but there is still considerable uncertainty between the global models with regards to timing. Above normal temperatures will continue through the forecast period, with highs mainly in the 50s and 60s. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 644 PM CDT Sun Mar 26 2017 KJMS is the aviation concern for the 00Z TAF period. Fog is forecast to develop in eastern areas of the state by 08Z. VLIFR visibilities and ceilings are expected to impact KJMS through Monday morning. Though fog may nose into KBIS, and perhaps KMOT, VFR conditions are expected in western and central areas. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AC SHORT TERM...ZH LONG TERM...ZH AVIATION...AC
Area Forecast Discussion
National Weather Service Caribou ME
1043 PM EDT Sun Mar 26 2017 .SYNOPSIS... High pressure will move east of the area tonight as low pressure approaches from the Great Lakes. Low pressure will cross the area Monday into Tuesday. && .NEAR TERM /THROUGH MONDAY/... 1035 PM Update... Made some adjustments to the pops to bring percentages up across the southern sections such as sw Piscataquis County and southern Penobscot County. 00Z UA showed high pres ridge axis still well w of the region w/dry air in place. Satl imagery showed mid/high clouds across the north while clouds deck was lowering this evening. Latest radar trends showing returns showing up across the western section edging ene. Most of the activity was aloft as llvls very dry. The latest run of the HRRR mesoscale model doing well w/the precip placement. A frontal boundary was in place across the region and radar returns were lining up along this boundary per the 00z sfc analysis. Temps look like they are going to be warmer than previously forecast and adjustments were made to bring them overnight. Will monitor the coast as some freezing precip is possible during the morning hrs before going over to rain in the afternoon. Previous Discussion... Mainly clear skies this evening will give way to increasing clouds tonight in advance of an approaching warm front. The air mass across the region is very dry with dew points down around zero across most of the region as of mid afternoon. The very low dew points and light winds will allow for some radiational cooling this evening before clouds thicken up after midnight. The coldest reading are likely to be across far northeast Aroostook County and the St John Valley where lows are expected to fall into the single digits above zero before clouds thicken later tonight. With the very dry low level air in place, it will also take a while for precipitation to reach the ground, so not expecting precipitation to develop until well after midnight across the west and probably not until around or a bit after day break across Northeast Aroostook and the St John Valley. Overrunning precipitation will continue overspread the region early Monday. Across the north the precipitation should remain mainly snow much of the day. Across central and interior downeast areas, expect snow to mix with sleet and freezing rain by afternoon. Across the downeast coast, expect a brief period of mixed precipitation in the morning to transition to plain rain by afternoon. A weak area of low pressure developing along the front to our south will cross the gulf of Maine during Monday afternoon, keeping the low level cold air in place. Thus, have leaned with cooler mos numbers for highs on Monday. Winter Weather advisories have been issued for all of Northern Maine for Monday. With the low level cold air expected to hang tough into the afternoon, have also included the Penobscot region and greater Bangor region, as well as all of interior downeast in the Winter Weather Advisory. There could be a mix even along the downeast coast into Monday morning, but thinking there may be enough warming for a transition to all rain by afternoon, thus have not included in the advisory at time. Highs on Monday are expected to range from the upper 20s across the north to the low to mid 30s along the coast. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... A large but poorly organized storm system will be moving into the area Monday evening with one low center along the coast and another to our west. Temperatures Monday evening will be warm enough for some light rain and drizzle Downeast. A mix of snow, sleet and freezing rain is likely across the north with all snow possible across the far north near the St. John Valley. Precipitation will generally be light, and will diminish late at night as one low center near the coast moves east and another remains back across Quebec. As the Quebec low crosses the area on Tuesday, some rain showers will be scattered over the region. Any showers may be mixed with some sleet or snow pellets across the far north with little or no accumulation expected. Some light rain, and snow showers across the north, may continue into Tuesday night as a weak occlusion crosses the area. Drier air should then begin moving into the region on Wednesday. However, low pressure consolidating south of Nova Scotia will have an inverted trough extending back across New Brunswick on Wednesday. If this inverted trough sets up further west, some scattered rain and snow showers could be possible. For now, will only have sight chance of snow or rain showers on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Low pressure will move away to the east Wednesday night into Thursday as gusty northwesterly winds follow. The air will only be moderately cooler with highs Thursday expected to be in the 30s north and 40s Downeast. High pressure will then build over the area Friday into Saturday bringing plenty of sunshine. Low pressure will be tracking off the Mid-Atlantic coast on Saturday, but should track far enough south to miss our area. Generally dry and mild weather is then expected late next weekend as upper level ridging along the east coast combined with low pressure over central Canada brings a southwesterly flow across the area. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... NEAR TERM: VFR through most of tonight. Conditions will deteriorate to MVFR 09z to 12z, then to IFR in a wintry mix on Monday at all terminals. SHORT TERM: IFR conditions in low clouds and snow and rain are expected Monday night through Tuesday. IFR conditions Tuesday evening may improve to MVFR late at night, then VFR on Wednesday. VFR conditions are likely on Thursday as high pressure approaches. VFR conditions in high pressure are expected on Friday. && .MARINE... NEAR TERM: Winds/seas will remain below small craft advisory levels tonight. Winds/seas will begin to increase to small craft advisory levels by late Monday afternoon. Visibilities will decrease to 1 to 3 nm in precipitation late tonight through Monday. SHORT TERM: A SCA will be needed Monday evening for southeasterly winds gusting up to 30 kt ahead of approaching low pressure. Winds will diminish late Monday night into Tuesday. Some fog may limit visibilities late Monday night into Tuesday as surface low pressure crosses the waters. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 5 AM to 10 PM EDT Monday for MEZ001>006-010-011-015>017-031-032. MARINE...Small Craft Advisory from 10 PM Monday to 3 AM EDT Tuesday for ANZ050>052. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Duluth MN
655 PM CDT Sun Mar 26 2017 .SHORT TERM...(This evening through Monday) Issued at 251 PM CDT Sun Mar 26 2017 A mid-level shortwave, with an associated sfc low, will advance across northern Illinois into Michigan tonight. A ribbon of positive vorticity advection that has supported rain/freezing rain across portions of the Northland this morning will weaken while the shortwave translates to the northeast. A secondary shortwave trough that has developed out of the Four-Corners region this morning will help push the previous shortwave to the east, while ejecting a northern stream ribbon of PVA into the Northland later this evening and overnight. Modest to weak isentropic lift looks to be associated with this northern stream, so not sold on it supporting any precipitation. Additional inhibition is provided by a push of drier 850-600 mb layer air, as evident in the latest NAM and RAP model soundings, which removes the deeper moisture that has been in place this morning. So, have decided not to include POPs with this shortwave at this time. Areas of fog are also expected to develop tonight as a low-level inversion traps boundary layer moisture, along with light winds in place. Model guidance is hinting at some of the thickest fog possible over the Iron Range area north towards the International Border, and along the Gogebic Range areas of Iron and Ashland counties. Visibilities could reduce to as low as 2 SM in some spots, but most of the Northland should see reductions between 3 to 5 SM. Chances of precipitation should ramp down somewhat later this evening, but maintaining over northwest Wisconsin overnight as weak PVA lingers over this area. The northern PVA ribbon looks to reinforce this lingering PVA. Moreover, deeper moisture should linger over this area through Monday morning. So, kept chances of rain showers for the eastern portions of our NW WI forecast area. Some freezing rain may also develop as temperatures cool down overnight and Monday morning. However, QPF should not be quite as high as it was this morning, so not expecting much ice accumulation, if any at all. Any lingering precipitation should diminish by Monday afternoon as high pressure builds into the region. .LONG TERM...(Monday night through Sunday) Issued at 251 PM CDT Sun Mar 26 2017 Split flow pattern will continue for most of the upcoming week, with the primary storm storm track remaining to our south from the central Plains States into the middle Great Lakes, and another series of fast-moving waves traversing Canada to our north in faster more zonal flow aloft. Overall, this will mean generally tranquil weather with a slow warming trend, although there will be a few small chances for precipitation with several weak disturbances traversing the region. Temperatures, especially at night and during the early mornings, may be sufficiently cold to support some wintry mixed precip, but overall this should not amount to many significant impacts. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 655 PM CDT Sun Mar 26 2017 Low pressure over southern Lake Michigan this evening will continue northeast tonight and an upper level disturbance will also move through the region. Light rain from the North Shore into the Pine City area this evening will continue east through the evening. The cloud forecast will be quite variable across the Northland tonight with mostly VFR conditions over far northern Minnesota this evening and MVFR/IFR ceilings around Lake Superior and over northwest Wisconsin. VFR conditions will develop further south through the evening but as the night progresses more MVFR and IFR ceilings will develop. Fog will also be possible, most widespread and dense around Lake Superior. As weak high pressure moves over the region Monday, conditions will gradually improve for most areas. && .PRELIMINARY POINT TEMPS/POPS... DLH 32 43 28 47 / 30 10 0 0 INL 30 46 27 48 / 0 0 0 10 BRD 33 54 30 56 / 10 10 0 0 HYR 32 45 26 52 / 30 20 0 0 ASX 31 42 26 45 / 30 10 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ SHORT TERM...JTS LONG TERM...Miller AVIATION...Melde
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
658 PM CDT Sun Mar 26 2017 .AVIATION... /00Z TAFS/ VFR conditions will prevail across area terminals through late evening. Clouds will develop along the Coastal Plains and then move toward the north this evening and over the I-35 sites by midnight tonight. MVFR cigs are anticipated by 05Z with IFR cigs starting around 08Z/09Z across Austin and San Antonio airports. There are indications from several HiRes models and guidance for cigs to go down as low as LIFR for Austin around the 12Z time frame and have included this as such for KAUS. MVFR are forecast to linger around through 16Z for the I-35 terminals with VFR returning by 17Z and staying that way through Monday evening. Southeasterly winds will prevail through the forecast period with 5 to 15 knots overnight into Monday morning and decreasing 5 to 10 knots Monday afternoon. KDRT should remain VFR through late tonight with MVFR expected by 11Z. There is a chance for cigs to lower to LIFR for an hour or two just like this morning and have added it to this forecast cycle. Good mixing takes place out west along the Rio Grande by late morning with VFR returning by 16Z Monday. && .PREV DISCUSSION... /ISSUED 319 PM CDT Sun Mar 26 2017/ SHORT TERM (Tonight through Monday Night)... Severe weather risk this afternoon remains non-zero but is still extremely marginal. Currently, satellite imagery is showing some bubbling cu from Mason County to Fayette County. Latest LAPS soundings show a weak cap struggling to hold on this afternoon and RAP forecast soundings keep it holding on through out the afternoon. Also of note is the presence of about 20-50 J/KG of CIN working against heated parcels at the surface. If a surface boundary of some kind were present, concerns would be much higher for the chance for CI this afternoon, but with surface dewpoints in the 50s west of I-35 and lack of lifting mechanism present east, think its very unlikely parcels will be able to tap into the ripe conditions aloft. SPC mesoanalysis shows LFC heights over 4000m thus surface parcels will need to overcome inhibition, weak surface moisture, and without any help to lift it to get to that height. Thus, confidence is extremely low for the chance for storms. Should one occur though, effective bulk shear, lots of instability, and strong mid level lapse rates all mean the possibility for strong to severe storms with large hail and damaging winds. LONG TERM (Tuesday through Sunday)... The focus for the short term will be the prospect of severe weather with our next upper low Tuesday and Wednesday. SPC has already outlined marginal to slight risk for large hail, damaging winds, and tornadoes Tuesday and a day 4 area outlined for the Austin area and northeast Wednesday. Our best timing for severe potential will likely be late Tuesday night, and maybe as late as early Wednesday morning (after midnight) as we inherit a mature system that develops near Abilene. Latest ECMWF shows convection initiating along the dry line near the Childress area and unzipping southward to Del Rio by midnight Tuesday night. Overnight, these cells become more dynamically driven and likely coalesce into a linear system that pushes across the CWA from the west and impacts the I-35 corridor by 12Z Wednesday morning. While PWAT values over 1.5" have been advertised thus far, both GFS and ECMWF quickly exit the system after 18Z Wednesday and should limit flash flooding potential. Should this system indeed become a linear system as advertised, the principle threat should be damaging straight line winds and hail. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 67 88 67 84 67 / 10 10 - 20 40 Austin Bergstrom Intl Airport 66 88 67 84 67 / 10 10 - 20 40 New Braunfels Muni Airport 66 88 67 84 67 / - 10 - 20 40 Burnet Muni Airport 63 85 63 80 64 / 10 - - 30 70 Del Rio Intl Airport 60 92 66 87 62 / - 0 - 30 50 Georgetown Muni Airport 66 87 65 81 65 / 10 - - 30 50 Hondo Muni Airport 65 92 66 85 66 / - - - 30 40 San Marcos Muni Airport 66 89 66 84 68 / 10 10 - 20 40 La Grange - Fayette Regional 68 87 67 84 69 / 10 10 - 10 30 San Antonio Intl Airport 67 89 68 84 68 / - - - 30 40 Stinson Muni Airport 67 89 67 84 68 / - - - 20 40 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...17 Synoptic/Grids...Allen Public Service/Data Collection...Williams
Area Forecast Discussion
National Weather Service Green Bay WI
657 PM CDT Sun Mar 26 2017 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Monday Issued at 318 PM CDT Sun Mar 26 2017 The latest RAP analysis and satellite/radar imagery show low pressure spinning along the Illinois/Wisconsin border early this afternoon. Rain showers continue to wrap around the low across much of eastern WI. Where its not raining, periods of drizzle are occurring into north-central WI. Visibilities improved with the arrival of more persistent showers, but dense fog does exist in close proximity to the surface low. Looking upstream, broken clouds prevail all the way into eastern North Dakota. As the low lifts northeast, precip trends are the main forecast concern. Tonight...Low pressure will be moving northeast from southern Lake Michigan to Lake Huron tonight. The most persistent showers will likely occur over northeast Wisconsin during the evening where the warm conveyor belt wraps around the upper circulation. Progged soundings indicate that saturation remains pretty deep up to 700mb for most areas through the night though, so even if showers have the highest coverage over the northeast, cannot rule out isolated showers and/or areas of drizzle elsewhere. Winds will lighten a bit through the night, which will support lowering visibilities with the ample moisture in place. However, dense fog appears only possible near the center of the surface low, that will pass southeast of the area. So think we may escape without a dense fog advisory, though it may be close along the lakeshore. Without any semblance of temperature advection in addition to the widespread low clouds, expect little fall of temperatures tonight. The warmer temperatures should confine any freezing precip right near the U.P. border, if there is any. Monday...The upper low will exit the region, but will see a weak shortwave move across northern WI and the Upper Peninsula. This shortwave will bring a chance of showers, but coverage should be limited due to weak forcing. Otherwise, cloudy conditions should prevail for much of the day with little dry air to push out the moist airmass. North-central WI has chance for partial clearing late in the day behind the shortwave. Highs will return into the low to mid 40s. .LONG TERM...Monday Night Through Sunday Issued at 318 PM CDT Sun Mar 26 2017 After wet period across the area, the long term will start off on a drier note, but another system at the end of the week will bring wet/wintry weather back as another low pressure system tracks across the Great Lakes. No drastic temperatures swings are expected, with near to above normal readings. For Monday night, lingering light showers or sprinkles are possible as low pressure passes across the Ohio Valley, a mid- level trough passes across Lake Superior, and a departing upper jet Monday evening is quickly followed by an approaching upper jet overnight into Tuesday morning. Think slight chance pops will cover for the evening hours. Drier air works into the area by Tuesday, so dry conditions are expected. Tuesday looks to be the best chance to see some sunshine this week, but forecast soundings are showing some lingering moisture both at low and mid- upper levels which could lead to some clouds. Tuesday also looks to be the warmest day of the week, with highs in the upper 40s to lower 50s for most locations. Surface high centered over northern Ontario early Wednesday will extend/shift south and east into the Great Lakes on Wednesday. The surface high along with mid-level ridging will provide for a dry day. An impressive moisture push from the west and southwest ahead of the next low pressure will bring mostly cloudy to the area by afternoon as a thick mid layer cloud deck is expected, with some lower clouds possible too. Dry weather looks to hold on until early Thursday morning, then all eyes will be on an approaching low pressure system. The mid- upper closed low will eject out of southwest U.S. during the day on Wednesday, then be on our doorstep Thursday morning (GFS a little slower). The GFS remains farthest south with the system and only brushes central and east central WI with some precip. ECMWF/Canadian remain farther north. Other smaller scale differences exist, especially with where the deformation band will set up on Friday. Temp profiles will be critical as the precip arrives on Thursday (and through the whole day if current trends continue), with the heaviest precip in the Thursday afternoon/evening timeframe and a secondary max possible sometime on Friday as the low pressure passes just to our south/east. The way it looks now, low level temps and wet-bulb temps look to be just cool enough for evaporative cooling effects to allow the precip to start off as a wintry mix Thursday morning, assuming the precip arrives on time. As the heavy precip moves in later in the day, a change over to rain is expected for the entire area. That said, the heavier precip will keep the temp profile very close to the rain/snow line, so there is a chance the precip could stay a wintry mix longer, especially over the north. A change over back to a mix is possible Thursday night as temps cool. This far out a blend of the models seems reasonable (least confidence in the GFS), but adjustments will likely be needed as we get closer to the event and confidence on how low level temps will behave becomes more clear. After the system pulls out on Friday, dry weather returns to the area on Saturday as brief ridging builds across the Great Lakes. Chances for precip arrives again on Sunday as a fast moving clipper type system crosses southern Canada, but models differ on how far south this system will track. && .AVIATION...for 00Z TAF Issuance Issued at 656 PM CDT Sun Mar 26 2017 IFR conditions will continue through midday Monday or maybe a bit longer as low pressure moves slowly away from Wisconsin. Light rain will accompany the low clouds at times. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Bersch AVIATION.......RDM
Area Forecast Discussion
National Weather Service Jackson MS
930 PM CDT Sun Mar 26 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... Latest surface analysis shows a low over SW Oklahoma with decent convective coverage in the warm sector and along the dryline. A closed mid- and upper-level low was centered over W Kansas with an associated trough extending through the Southern Plains. Surface ridging along the East Coast has allowed southerly flow to continue across the CWA ahead of the advancing system out of the Southern Plains which has helped to keep warm temperatures and upper 50s to low 60s dewpoints across the region. For the remainder of the overnight, latest hi-res CAM guidance is in agreement on weakening and eventually dissipating the organized convection emanating from the Southern Plains as it moves into an area of capping and less instability/forcing. This will limit any convection concerns across the area tonight and into early tomorrow morning, however an isolated shower or rumble of thunder cannot be entirely ruled out across the Delta. Some of the hi-res guidance has been more aggressive in shower/isolated storm development after sunrise tomorrow morning as a remnant outflow boundary interacts with increasing moisture and instability, however given the capping issues confidence is not very high on more than isolated coverage at the moment. Patchy fog will also be possible overnight and into tomorrow morning mainly in the southeast where the best moisture return and calmer winds will be. Coverage and visiblities are not expected to be great enough to warrant mention in the HWO at the moment, but will let the next shift monitor any trends. Otherwise, temperatures will stay on the mild side area wide with southerly flow and increasing cloud cover through the period. See the prior discussion below for information regarding Monday`s severe weather potential. /TW/ Prior discussion below: Tonight and Monday: WV imagery this afternoon showing impressive cold core system moving into the central Plains with warm advection ascent taking shape over TX/OK. Meanwhile in our neck of the woods, much of the cloud cover from this morning has mixed away as dewpoints have fallen into the 50s. Better dewpoints are poised over southern sections to advance northward over the area again tonight. As this occurs, fog and low clouds will spread in from the south mainly after midnight. The HRRR is indicating that currently developing MCS over OK will grow eastward overnight into AR, but diminish toward sunrise over eastern AR as it moves into a more capped environment. Some concern exists for its outflow to help force new convection over northern MS in the morning, but models soundings continue to show impressive capping that does not look to weaken until the afternoon. A less impressive cap will exist over the northeast and it is in this area that convection may initiate by afternoon. While a damaging wind threat will exist with the storms, environmental parameters suggest that large hail will be the primary threat. Cells look to be scattered in nature during the afternoon and early evening until the surface cold front moves in later in the evening. South of I20, the cap strength looks to remain strong enough to only allow for isolated convection, but severe potential will exist with these storms as well. The convection will diminish toward late evening with the loss of daytime heating./26/ Monday night through the week...As the system that should bring us some potential severe weather departs to the northeast Monday night, it will leave a cold front draped across the north central portions of the ArkLaMiss region. Some light showers may linger along or near this front Monday night but the remainder of the region will begin to dry out. Upper ridging will move overhead for Tuesday, but as daytime heating occurs, additional showers/storms may develop around this stalled front. The upper ridge will push east through Tuesday night and into Wednesday but will still have some hold on our area Wednesday. This will keep conditions warm but mostly dry. The aforementioned stalled front will move north as a warm front during the day on Wednesday, which could ignite some warm advection showers across my far northern counties(or develop completely north of my CWA). Our next weather system will continue to develop out to our west. By Wednesday evening, a 998mb surface low will be located across the Rolling Plains of Texas as the upper trough/closed low will be located slightly further north across the Texas Panhandle. A dryline feature will be across the eastern Pineywoods of Texas with storms along/ahead of this feature in western Louisiana. Across our area, a rather moist and unstable airmass will be in place with dewpoints in the lower to mid 60s and temperatures having reached the lower to mid 80s during the afternoon. During the evening hours, as the surface low tracks to the north and east and the upper trough starts to swing east, this line of storms should enter my western counties/parishes and continue to track east overnight. Our atmosphere will be rather unstable with steep lapse rates (Vertical Totals of 28-31C and 7-8C/km mid level lapse rates) and greater deep layer shear than we saw in previous events (40-45kts 0-6km shear) and helicities are depicted as being 200-400 m2/s2. All of this suggests that all hazards will be possible. Conditions look just as good on Thursday, especially if the overnight line doesn`t work over the atmosphere. Looks like there could be several rounds of weather with this event from Wednesday night through Thursday. In addition, with PW values around 1.5-1.7 inches, there could be some locally heavy rainfall which perhaps could lead to some isolated flooding instances given recent rainy conditions. Will continue with the slight risk as highlighted by the previous shift, but expect that this will be increased as the event gets closer and more details are ironed out. As the system pulls off to the northeast by Thursday evening/night, rain will move out of the area and upper ridging will again move in for the early part of the weekend. Springlike temperatures will continue through the period with highs in the 70s and 80s and lows in the 50s and 60s. /28/ && .AVIATION... 00Z TAF discussion: Very few clouds were noted satl imagery at 2330Z and VFR conds were observed at all TAF sites. VFR conds wl prevail this evening but MVFR vsby wl be psbl HBG-MEI by 06Z and lower to IFR by 11Z. MVFR cigs are expected to develop at most sites by 09Z lowering to IFR by 11Z before improving after 15Z Mon. TSRA activity wl come in vcty of GLH by 15z and elsewhere Mon aftn. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 64 83 63 81 / 2 39 37 29 Meridian 62 82 63 81 / 2 42 35 30 Vicksburg 64 83 64 81 / 1 37 35 28 Hattiesburg 64 82 64 82 / 9 34 21 27 Natchez 65 82 66 82 / 2 37 26 27 Greenville 63 79 59 76 / 6 42 36 19 Greenwood 63 81 61 77 / 5 55 58 25 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ TW/22/26/28
National Weather Service Jackson KY
1054 PM EDT Sun Mar 26 2017 .UPDATE... Issued at 1054 PM EDT SUN MAR 26 2017 Thunder has ended across the area, and will remove this for the rest of the night. Some isolated to scattered showers will continue to linger across the area through the next few hours, before diminishing. There are some thinner spots in the cloud cover upstream, and with a slackening pressure gradient expected through the rest of the night and recent rainfall, will include some patchy dense fog across the area. Low temperatures will average in the mid 50s, and have mainly freshened up the hourly temperature drop off. Updates have been sent. UPDATE Issued at 813 PM EDT SUN MAR 26 2017 A few clusters of showers and isolated thunder are shifting northeast across portions of eastern Kentucky early this evening. One of these will pivot through the I-64 in the next hour, while another one will exit into West Virginia. The latest HRRR has been showing additional activity firing up in the next 2 to 3 hours; however, with the better forcing moving off to the northeast and the loss of heating, am leaning more towards a gradual weakening trend, which has been the case upstream. Have freshened up the POP trends over the next few hours, with thunder chances ending in the next 1 to 2 hours, as the aforementioned clusters of convection exit. Have also included some patchy fog, with pockets of clearing and some locally heavy rainfall having occurred. && .SHORT TERM...(This evening through Monday night) Issued at 300 PM EDT SUN MAR 26 2017 The short term period will be active, with numerous showers and isolated thunderstorms moving across the area through around 2Z this evening. A few of the storms this afternoon could produce hail and strong wind gusts. The thunder chances should only last through 23 or 0Z, as any remaining instability and best forcing should be gone after that. General rain showers are expected overnight, and these will taper off steadily through 6Z, and should be gone by around 9Z. After a very brief reprieve, we should see more showers moving into the area from the south and southwest between 12 and 13Z on Monday. Isolated to scattered thunderstorms will be possible again after 17Z on Monday. There will be a good chance of thunder Monday night as well, as a strong area of low pressure aloft and a fast moving but weak cold front both move across the region. Mostly cloudy to cloudy skies will also be on tap, as ample moisture will continue streaming into the area from the south. Temperatures through out the period will continue to run well above normal, with nightly lows in the 50s, and highs on Monday in the low to mid 70s expected. .LONG TERM...(Tuesday through Sunday) Issued at 440 PM EDT SUN MAR 26 2017 The period is expected to begin with a mid and upper level trough moving through the OH Valley region and into the Appalachians that shifts east during the day on Tuesday and takes deeper moisture with it. The associated surface low is expected to move into the Mid Atlantic states by Tuesday evening and take the cold front across the area on Tuesday morning. Mid and upper level ridging should build in behind it, with surface high pressure nosing into the OH Valley at midweek. This should bring a break in the unsettled weather with mild and drier weather from late Tuesday evening through Wednesday night. The pattern will remain rather active with the next in a series of upper lows or shortwaves moving from the Southern Rockies across the Plains and into the mid MS and OH Valleys from Wed through Thursday evening. There is also some timing and strength differences with the upper and surface low beyond Thursday. The general consensus however, is for the upper and surface system to track to the west and north of the area from Thursday through Friday night and bring additional rounds of showers and a few thunderstorms to the area. This system should continue to depart on Saturday with surface and upper level ridging building in for a dry end to the weekend. Chances for showers will be highest to start the period, followed by a lull at midweek. The next system will bring another period of unsettled weather with pops in the good chance to likely range form Thursday into Friday evening. At this point, next weekend is expected to end on a dry note. High temperatures should average above normal for most of the period, although highs on Wednesday and Saturday should be near normal for late March/Early April. Lows will also be mild and at this point are not expected to fall below 40 at any point, even in the normally colder valley locations. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 813 PM EDT SUN MAR 26 2017 Showers and isolated thunderstorms will gradually come to an end across the area through 06z. Outside of showers, mainly VFR conditions will be seen. Some lower stratocu looks to develop between 06 and 12z, mainly along and north of a line from JKL to PBX. Patchy fog may also reduce visibilities down to MVFR, although this will depend on clearing and how light winds become overnight. Another round of scattered showers and a few thunderstorms will threaten during the late morning and afternoon hours on Monday. Winds will remain out of the south and southwest through the period, averaging between 5 and 10 kts during the day and around 5 kts at night. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...AR LONG TERM...JP AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service Marquette MI
831 PM EDT Sun Mar 26 2017 .SHORT TERM...(This evening through Monday) Issued at 320 PM EDT SUN MAR 26 2017 Water vapor imagery and RAP analysis show a mid level low centered over northern IL. Deep moisture associated with this feature surged back to the n across Upper MI last night into today, bringing periods of -ra/-fzra. Upslope e to se flow also resulted in some patchy dense fog this morning into early afternoon over portions of the Keweenaw Peninsula...Dickinson and southeast Marquette counties. Models show the mid-level low and assoc trough lifting ne through Lower Mi this evening and then into Ontario late tonight/Mon morning. With movement of the mid-level trough the 850mb trough and weak isentropic ascent also shifts e tonight, so expect pcpn over mainly the central and eastern fcst area to diminish. However with abundant moisture, developing nnw upslope flow and approaching weak shortwave, some -ra/-fzra will remain possible over the w tonight. Sfc temps should slip back to around freezing over the w and n central, so there may still be a little bit of icing at some locations late tonight. However, accumulations should be minor so no statement will be issued at this time. Expect some fog as well. Weak northerly flow between sfc low over eastern Ontario and sfc high building into south central Canada will result in murky weather conditions with some fog and possible light drizzle or freezing drizzle Mon morning mainly over upslope locations of west and north central U.P. Forcing from incoming northern stream shortwave could enhance upslope pcpn turning dz/fzdz to -ra/-fzra for a time late morning into mid aftn. NAM soundings suggest could even be brief period of sleet or snow mixing in over west and northwest with evaporative cooling aloft. Limited moisture depth as noted on NAM soundings will not warrant anything more than slight chc to low chc pops. Expect highs in the mid 30s to lower 40s, warmest e and se under cloudy skies. .LONG TERM...(Monday night through Sunday) Issued at 401 PM EDT SUN MAR 26 2017 Rather benign weather is expected through much of the period as a slow-moving mid to upper ridge is gradually replaced by a mid-level low drifting NE from the southern plains. Lingering low-level moisture may allow for a light wintry mix for the higher terrain along Lake Superior, and patchy fog across most of the CWA, Monday night. A fairly shallow and sharp inversion may keep low clouds across the area well into Tuesday afternoon, but gradual mixing through the day should erode most of the clouds by the evening. Dry conditions are then expected through Wednesday with the ridge settling over Lake Superior and northern Ontario. N to NE winds will likely keep temps in the mid 30s both Tuesday and Wednesday along Lake Superior. The NW extent of a somewhat closed mid-level low will then brush mainly the SE half of the CWA Thursday night into Friday night. Again, precip type will be in question with cloud-layer temps aloft only slightly below freezing. However, marginal upper-level cloud seeding and the absence of a pronounced warm layer should limit the amount of freezing rain. Inconsistencies in the model guidance develop by next weekend, with mixed signals regarding a weak mid-level trough traversing the area Saturday night. Will maintain chance PoPs at this point. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 822 PM EDT SUN MAR 26 2017 Abundant low-level moisture over the area should lead to prevailing LIFR conditions at KIWD/KCMX/KSAW through tonight. Some -FZRA is still possible but temperstures are expected to remain at or just above freezing. Fog late tonight may be low enough to drop vsby near landing minimums at KSAW. Drier air moving in on Monday will result in improving conditions during the morning into the MVFR range at KIWD and KCMX. IFR cigs should still linger at KSAW into the afternoon. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 320 PM EDT SUN MAR 26 2017 With no signIficant weather systems affecting the Upper Great Lakes this week, no gales are expected on Lake Superior. In fact, winds will mostly be under 20kt. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...Kluber AVIATION...JLB MARINE...Voss
Area Forecast Discussion
National Weather Service Omaha/Valley NE
628 PM CDT Sun Mar 26 2017 .SHORT TERM...(Tonight through Wednesday) Issued at 305 PM CDT Sun Mar 26 2017 Main forecast concerns are in regards to precipitation timing and location tonight into Monday morning, then precipitation chances returning Tuesday and continuing into the long term. Upper air charts from 12Z this morning had the following main features of interest. A jetstreak of over 100 knots at 300 mb was moving toward the northern CA coast. At 500 mb, one closed low was near the IA/MO/IL border and another was over southeast CO. The second low had 12 hour height falls of up to 100 meters at KABQ. As of mid afternoon, that feature was moving into southwest KS. Like yesterday, there was some convection right near the center of the low with the cold pocket. Convection also noted over OK in part of the baroclinic leaf that had formed ahead of the low. At the surface - low pressure was over the OK panhandle, while a warm front extended east from the low toward the MO/OK/KS border area. Dewpoints in the 50s F were streaming northward south of the front. Closer to home, a weak surface ridge was over eastern NE and western IA with temperatures in the 40s and dewpoints in the upper 30s/lower 40s. Tonight...we should see an increase in showers into the southern parts of the forecast area. Trend from previous forecast was good, just modified timing, northward extent of POPs and also increased those POPs a little near the KS and MO borders. A fair amount of weight was given to the RAP, experimental HRRR and NAM output. General consensus is that amounts should be mostly less than 0.25 inches, although the 12Z GFS suggested there could be some amounts higher than that. Convective potential seems best south of our area, so did not mention thunder at this time. Showers should linger in the southeast part of the forecast area Monday morning, then we look for a dry period from Monday afternoon into Tuesday morning. By 12Z Tuesday, a new mid level closed system should have moved into the four corners region, with modest diffluent flow over the central Plains. That low is expected to track into western Oklahoma by Wednesday evening. Increasing moisture and forcing should result in development of light rain or showers over our western counties by late Tuesday afternoon. The 12Z GFS was just a bit faster than the 00Z ECMWF, so there are some timing differences that will need to be resolved the next few shifts. But by Tuesday night, most model guidance brings rain into our area. Right now, think that precipitation amounts from Tuesday Night into Wednesday should be from 0.25 to 0.75 inches. The ECMWF does show a bit more than that though. .LONG TERM...(Wednesday night through Sunday) Issued at 305 PM CDT Sun Mar 26 2017 Rain should linger Wednesday night and then decrease from west to east on Thursday as the mid level system moves east and the deformation zone weakens. Heaviest rain, potentially over an inch, should be across southeast NE into southwest IA. Most if not all of the precipitation should be in liquid form, but did allow for a very short window of a rain/snow mix west of highway 81 in northeast NE late Wednesday night into mid morning Thursday. The period from Thursday night into Friday evening looks mainly dry, but another system could bring rain for at least parts of the area next weekend. Model agreement is not great by that time, so confidence does drop to normal or below normal by Day 7. The ECMWF is a bit wetter than the GFS, especially Saturday into Saturday Night. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 612 PM CDT Sun Mar 26 2017 MVFR/patchy IFR cigs will prevail overnight tonight with a large area of low level moisture in place. May also see some patchy MVFR vsbys with fog. Mid-level cyclone over western Kansas will track across eastern Kansas through tonight. The better low level forcing will remain to the south of the TAF sites although there is some mid and upper level forcing which will try to spread some of the light rain toward southeast Nebraska. Forecast soundings are hinting that as the storm system exits the area in the afternoon that we will see the clouds scatter out. Trended these improving conditions into the TAFS 18-21Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Miller LONG TERM...Miller AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Spokane WA
435 PM PDT Sun Mar 26 2017 .SYNOPSIS... One storm system will bring light rain and mountain snow tonight into Monday morning. Showery weather is expected through Tuesday then a widespread moderate precipitation event will arrive on Wednesday and Thursday. Friday will bring a dry break period before more unsettled weather for next weekend. && .DISCUSSION... Tonight through Monday night: A moist frontal system will pass through the region tonight and Monday delivering periods of light rain and mountain snow. There is a decent moisture fetch tied to the system however the dynamics will be weak and splitting with the strongest lift tracking south into Oregon and most locations will receive less than a quarter of an inch from this system. The exception will be along the Cascade Crest, Blue Mtns, and into the Camas Prairie where upward of half an inch will be possible. As of 2PM...we were monitoring the first band of rain associated with the warm front expanding into Ern WA and N ID. Rainfall amounts have been light and on the order of a few hundredths or less. Several runs of the HRRR indicate the potential for a brief break in the rain behind the warm front however a cold front currently on the WA Coast will limp through the region allowing a line of precipitation to redevelop overnight. Satellite imagery also indicates a strengthening jet digging down the backside of the trof. Not only will this serve to split the energy south but also slow the entire system down...thus the slow cold front passage. The front will also loosen its thermal packing or frontal structure, all factors contributing to a rather light precipitation event. The front will begin to clear east of the region Monday morning then cooling aloft will aid to destabilization and likelihood for convective showers. Just about all locations will have a chance for an afternoon shower but westerly flow will keep the lee of the Cascades at a slight risk and rising terrain of Ern WA and N ID, greatest. There is a slim chance for an isolated t-storm as well Monday afternoon but with marginal CAPE of 150-400 J/kg and 0-6km shear less than 15 kts, felt the threat was too low to include in the forecast at this time. SREF guidance did increase toward 20% probability for a lightning strike across SE WA and NC ID but the best sunshine may be in the southwestern too early to call where a rogue strike or two may actually occur. Temperatures tonight will remain mild and generally above freezing for most lowlands due to an abundance of cloud cover and light rain. Highs on Monday will be warming into the upper 40s to 50s just a few degrees shy of March 27th normal`s. Monday night will feature a better chance for temperatures to dip in the lower 30s coupled with patchy fog. /sb Tuesday through Sunday...Models are in reasonably agreement in depicting a continued active and progressive spring pattern featuring at least one and maybe two more good atmospheric river hosings punctuated by a brief dry interlude. Tuesday will start out dry and seasonably cool...but the next feed of deep moisture will become favorably oriented during the day with an onset of light rain mainly over the mountains north of the basin and possibly the Idaho Panhandle...but for the most part Tuesday will be the increasingly cloudy moistening period before the main event. Tuesday night and Wednesday...the next atmospheric river will be favorably directed into the forecast area and enhance into universal light rain and high mountain snow through Wednesday...first along a warm front and then along the trailing cold front. At this time at appears the deep basin will pick up a third of an inch of rain from this system with amounts increasing as one moves east culminating in around three quarters of an inch in the eastern basin zones and Idaho Panhandle valleys...with around an inch in the mountains but much of this will fall as snow above 4500 to 5000 feet. this will be good for building up late season high elevation snowpack especially in the Cascades and mountains along the Canadian Border. This further shot of moderate to heavy widespread rain will likely cause a response on area rivers draining eastern Washington and north Idaho late this week...possibly delaying the recession below flood stage on the St. Joe and quite possibly promoting another minor flood spike on the Little Spokane by Friday. Other mainstem rivers may rise but levels are now receding to low enough to handle this storm without flooding. The areal flood/small stream issues around the region will either be aggravated somewhat or at least temporarily halted from improving significantly. Wednesday night and Thursday...The cold front passage of Wednesday will herald the arrival of a cool upper level trough depicted by all the latest model runs. This suggests continuing showers driving into the Idaho Panhandle...and the possibility of scattered showers over the eastern half of the forecast area with a basically dry deep basin in a typical spring-time unsettled and seasonably cool regime. Friday and Friday night...The trough moves east and a quiet upper level ridge takes over providing guarded confidence of a much needed dry day on Friday. Saturday through Sunday...Model agreement deteriorates this far out with the GFS and Canadian models maintaining a flat ridge over the region...but not the nice and quiet kind of dry ridge. this will be a ridge which is welcoming another atmospheric river into it`s westerly flow which implies another round of light rain...largely skipping the deep basin but enhancing over the eastern zones and focusing on the northeast and Idaho Panhandle mountains. The ECMWF model brings a short wave disturbance through the region. So which ever model is correct...increasing pops for this period looks quite plausible. Through the next week the flow regime will remain progressive...with little opportunity for different transient air masses to become established. Thus a temperature regime characteristic of a polar maritime air mass is a safe bet...warmer than normal low temperatures rarely and only locally dipping below freezing and slightly cooler than normal high temperatures impacted by the frequent presence and proximity of rain or at least significant cloudiness. /Fugazzi && .AVIATION... 00Z TAFs: A warm front followed by a cold front passage shorty after tonight/tomorrow morning will allow for a prolonged interval of generally light precipitation over the aviation area. MVFR ceilings and visibilities associated with the precipitation (lowland and valley rain with snow generally above 3500 feet MSL) will linger at times with improvement most likely after 17Z Monday. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 38 50 34 49 39 50 / 80 40 20 40 60 100 Coeur d`Alene 37 48 34 46 37 49 / 80 70 30 40 50 100 Pullman 38 49 34 49 39 51 / 80 40 20 20 20 100 Lewiston 43 55 37 55 42 56 / 80 40 20 20 10 70 Colville 36 49 32 48 36 49 / 70 30 10 40 60 100 Sandpoint 34 45 33 45 34 46 / 80 60 20 50 50 100 Kellogg 35 45 33 44 34 46 / 90 90 40 40 40 100 Moses Lake 38 57 37 57 42 57 / 80 20 10 10 60 100 Wenatchee 37 54 36 53 38 54 / 70 20 10 20 70 100 Omak 36 53 33 51 38 53 / 90 20 10 30 70 100 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1034 PM CDT Sun Mar 26 2017 .UPDATE... A few more thunderstorms will remain possible for the next few hours in far eastern portions of the fa. However, the severe potential has decreased across the area. A cold front will continue to move across the area overnight with cooler air moving into parts of the fa. Adjusted PoPs, hourly grids, and sky cover have been adjusted to show current trends. Also lowered minimum temperatures in northern/western parts of the fa where temperatures are falling behind the front. && .PREV DISCUSSION... /issued 642 PM CDT Sun Mar 26 2017/ DISCUSSION... AVIATION... Severe thunderstorms are expected to move east away from OKC this evening while other strong or severe thunderstorms move across the OK-KS border area toward PNC later this evening. A cold front will sweep northwest to southeast overnight shifting winds to northwest. MVFR ceilings are expected to follow until around mid- day Monday. VFR conditions and lighter winds will arrive Monday afternoon. PREV DISCUSSION... /issued 258 PM CDT Sun Mar 26 2017/ DISCUSSION... Cirrostratus continues to stream overhead this afternoon ahead of the mid to upper low currently centered over SW KS. A few elevated storms developed within nose of low level moisture plume/WAA over central OK around 1 PM and have moved east of I35 now. Both the previously mentioned cloud cover and early moist convection will have an impact on instability for late this afternoon through this evening. However, despite cloud cover some CU can be seen through thin cirrus from near Chickasha to Lawton where an instability axis resides. This instability axis should slowly start to expand north and eastward through the late afternoon hours as height falls commence. The HRRR continues to indicate rapid development will occur along/ahead of the dryline around 23Z across central and south central OK. Very large hail and damaging wind gusts over 70 mph (especially east of I35 later this evening) will be possible. In addition, ~850 mb flow will begin to veer this evening increasing low level shear specifically along the I35 corridor. LCLs will also continue to lower as dewpoints climb into the low 60s. Expect highest tornado potential to be some time around 23-02Z this evening. The storms should quickly exit our eastern zones before 06Z tonight. A subtle cold front will accompany the mid to upper low late tonight through tomorrow morning, with some dry air advection. It will be a beautiful day tomorrow under the influence of a weak surface ridge, although some stratus may try to liner over the NE. The low level flow will then quickly return from the SE Tuesday as the next upper low traverses the four corners region. A fairly sharp dryline is expected by Tue afternoon from the NW panhandles into western north TX. Stout WAA and accompanying stratus may limit the severe potential Tue to a narrow axis over the SW. Later through the evening Tue, widespread showers and thunderstorms are expected with the approach of the closed low. This low will slowly meander over the central and southern plains through Thu, which could bust some of the drought. Some locations could receive over 3 inches of rainfall through late Thu. A brief break in rain chances will occur on Friday before yet another, even deeper, closed low passes over the southern plains. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 52 70 48 71 / 20 0 0 40 Hobart OK 47 71 49 67 / 10 0 0 60 Wichita Falls TX 50 75 52 74 / 0 0 0 50 Gage OK 42 71 47 60 / 20 0 0 70 Ponca City OK 48 67 45 69 / 60 10 0 20 Durant OK 58 75 51 75 / 60 0 0 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ 25/09
Area Forecast Discussion
National Weather Service Charleston WV
935 PM EDT Sun Mar 26 2017 .SYNOPSIS... Active, mild pattern continues in a parade of southern stream systems. One crosses this evening, followed by another Monday night and Tuesday, and then again Thursday through Friday. && .NEAR TERM /THROUGH MONDAY/... As of 920 PM Sunday... Took out thunder for entire area before midnight. Rain showers gradually decreasing from southwest to northeast after midnight, confined to far northeast WV by morning. As of 2 PM Sunday... The remainder of the afternoon will tell what comes of a negatively tilted trough axis pivoting through the middle Ohio Valley, and the left front exit region of a strong jet on the back side of the trough coming in close proximity of the diffluent area ahead of the trough axis. So far, only small breaks in the cloud cover have limited surface heating. Heating was more evident farther south, beneath and behind the upper level trough axis, where the first thunderstorms were firing up in eastern Kentucky early this afternoon. The WRFs appear to have this pegged as the beginning of the main shower/thunderstorm activity crossing the area this afternoon into this evening, as the categorical PoPs in the forecast depict. The low level reflection of the upper level trough is a warm occlusion that will push through the area tonight. Loss of daytime heating should end the thunderstorm threat tonight, while the last of the showers should end once the occlusion pushes through. Compromised between the faster GFS, HRRR and RUC, and slower NAM and WRFs in winding down the precipitation overnight tonight. Models depict morning stratus where the surface occlusion stalls over the middle Ohio Valley on Monday. The next short wave trough brings an increasing chance for showers and thunderstorms from the southwest late Monday. Used a blend of near term guidance for temperatures and dew points, which did not bring up any major changes from the previous forecast. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 4 PM Sunday... Upper level southern stream short wave trough crosses Monday night and Tuesday, bringing the next round of showers and thunderstorms. However, the timing of the system is such that the strongest thunderstorms will be to the west of the forecast area Monday afternoon, and then to the east on Tuesday afternoon. The system pulls out Tuesday afternoon and evening, but is likely to leave low level moisture behind in the form of stratus overnight Tuesday night into Wednesday morning. High pressure sails across to the north of the area Wednesday, followed by a southeast flow developing in its wake by Thursday morning, beneath an upper level ridge. Temperatures close to central guidance and remaining above normal, even in the wake of the system midweek. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 4 PM Sunday... The next southern stream upper level low approaches Thursday through Friday, before passing north of the area Friday night. This brings a surface warm front, along with an initial round of rain or rain showers, Thursday afternoon and evening. The surface cold front crosses Friday evening, as the surface low passes north of the area Friday night. Models have come in good agreement on this system. Showers and thunderstorms are most likely Friday into Friday night, but with the typical downslope shadow effect west of the mountains Friday in strong south to southeast flow in the warm sector ahead of the cold front. Northwest flow behind the system may bring upslope rain showers in and near the WV mountains on Saturday, with the latter part of next weekend more likely to bring dry weather. However, models are not too divergent on timing of yet another southern upper level low approaching late next Sunday. Temperatures close to central guidance and lower than the MEX. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... As of 920 PM Sunday... An upper level disturbance will continue to bring showers into the night time hours, mostly ending from southwest to northeast by around 13Z Monday. Thunder potential will mostly dissipate by 03Z with loss of heating. Look for brief MVFR/IFR VSBY in a few of the heavier rain showers. 15 to 20 kts of southerly flow just above the surface should generally keep IFR fog from becoming an issue. However, prevailing VFR ceilings become MVFR ceilings after 06Z, but with locally IFR ceilings possible mainly higher mountains. No IFR is forecast for major TAF sites overnight. Expect clouds lifting to VFR ceilings 3500-4500 feet by 15Z Monday. The rest of Monday will bring dry VFR weather, with at most a 4-6kft stratocu deck. Surface flow will become light south tonight, and then southerly 5 to 8 kts Monday afternoon. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY... FORECAST CONFIDENCE: Medium ALTERNATE SCENARIOS: There may be a bit more IFR ceilings overnight and early Monday morning, and timing of improvement to VFR on Monday may vary. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE MON 03/27/17 UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EDT 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 CRW CONSISTENCY H H H H H H H H H H M L HTS CONSISTENCY H H H H H H H H M M M L BKW CONSISTENCY H H H H H H H M M M M L EKN CONSISTENCY H H H H H M M M M M M M PKB CONSISTENCY H H H H H H H H H L L M CKB CONSISTENCY H H H H H H H H M M M L AFTER 00Z TUESDAY... Brief IFR possible in thunderstorms Monday night and Tuesday. && .EQUIPMENT... Radar site KRLX appears to have a faulty component that is leading to higher reflectivities than what should be observed at times. So far today and this evening, however, the radar has performed normally. Further evaluation and monitoring is expected prior to action being taken. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...None. OH...None. KY...None. VA...None. && $$ SYNOPSIS...TRM NEAR TERM...JMV SHORT TERM...TRM LONG TERM...TRM AVIATION...JMV EQUIPMENT...99
Area Forecast Discussion
National Weather Service Blacksburg VA
710 PM EDT Sun Mar 26 2017 .SYNOPSIS... Low pressure near Chicago will move northeast through the Great lakes and weaken as it passes into Ontario tonight and Monday. A second area of low pressure will move northeast out of the southern Plains crossing the Mid-MS Valley Monday, and across the Ohio Valley into the northern Mid-Atlantic Monday night and Tuesday. These weather features will result in unsettled weather across the central and northern Appalachians through Tuesday. Temperatures will remain well above normal through mid week. && .NEAR TERM /THROUGH MONDAY/... As of 659 PM EDT Sunday...Radar and METARs continue to indicate ongoing, though weakening rain showers from Roanoke to Reidsville NC eastward into western portions of Appomattox County. These showers stand to dissipate per recent HRRR/NAMNest output. Also watching stronger convective development to the the west and south of our forecast area, primarily in central West Virginia, associated with vort max pinwheeling northeast into southern Ohio around parent upper trough extending southeastward from the upper Midwest. Past couple HRRR runs, which have generally handled the spatial coverage of convection to our west the best since it partly initializes off radar, continues to suggest that some possible scattered showers/possible rumble of thunder may slip into Mercer, Summers and western Greenbrier Counties in WV as well as our southwest Virginia Tennessee Valley counties next couple hours. As we progress toward midnight, upper trough lifts to our northeast, leaving us in shortwave ridging overnight. As forcing becomes nebulous at best, except for some additional upslope convergence along the southern Blue Ridge, PoPs should be at their lowest overnight with shower coverage being even more isolated than they presently are. Given rather saturated air mass would expect skies to stay at least mostly cloudy. Lows only fall into the 50s tonight. Previous near-term discussion issued at 300 PM follows... Radar indicated a 30 mile wide band of rain showers propagating east across the central CWA. As of 3PM the leading edge was along the 220 corridor from Clifton Forge to Martinsville. Movement was to the east at 20 mph. Leading rain band was associated with a front aloft, arcing from NW to SE from Low pressure moving through the Great Lakes. The actual surface front was over western KY/TN, with additional bands/clusters of showers and thunderstorms scattered across the Ohio Valley. The initial rain band over our CWA has outrun any surface instability and has been weakening with time. Rainfall amounts have been averaging between a tenth to a quarter of an inch, but as this band of showers continues to move east, the overall qpf will diminish with amounts of a tenth of an inch or less. Timing suggests these showers will reach Highway 29 corridor...Charlottesville, Lynchburg, Danville, between 5-6PM. Behind the front aloft, some partial clearing was taking place, the rain only lasting a couple hours in duration. Once this initial rain area moves east, will have to wait for the instability driven showers over KY/TN ahead of the actual surface front to move east. Models suggest most of this activity will dissipate during the overnight, but until then will threaten our western CWA (primarily west of I-77 in VA/NC and west of Lewisburg or highway 219 in WV) this evening with potential for both showers and thunderstorms and an additional tenth or two of rainfall before midnight. As the main upper level low slides by to our northwest overnight, dynamic support will decrease. The actual surface front is forecast to wash out before crossing the mountains so this will maintain a persistent mild southerly flow across the forecast area overnight. As such, there will be a continued chance of showers mainly along and west of the Blue Ridge overnight, although nothing severe per waning instability. Some patchy fog is also possible, but cloud cover should prevent it from becoming widespread. On Monday, a second storm system will be moving northeast out of the southern Plains, crossing the Mid MS valley during the day and into the OH Valley Monday evening. Response will be the development of more showers and thunderstorms with focus primarily to our west across the OH/TN valleys. Model soundings suggest some instability driven activity may develop over our CWA during the afternoon associated with weak convergence near the Blue Ridge. Attm will advertise chance threat for showers/storms Monday, but coverage generally less than 50 percent and no mention of severe attm. Certainly can`t rule out a stronger storm or two if temperatures rise into the 70s permitting surface based CAPE in the 1000-1500 range. Temperatures through Monday will remain mild with readings 10 to 15 degrees above normal, and remaining well above freezing. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM EDT Sunday... During this portion of the forecast, a Pacific based system is expected to impact the region. Guidance among the models is in good agreement of bringing a shortwave trough eastward along the Ohio Valley and then into the New York City region Monday night into, and through Tuesday. This track will keep the region on the mild side of the system until the passage of its associated cold front Tuesday morning into the afternoon hours. Scattered showers and isolated storms across the area Monday afternoon, will lingering into Monday evening. The scattered showers will continue through the overnight, with coverage increasing towards daybreak in the west. There may be an initial increase in coverage across eastern parts of the area through the evening hours, but decrease to isolated coverage early Tuesday morning. As the front crosses the region on Tuesday, showers will be in greatest concentration coincident and just in advance of the cold front. Instability is progged to increase enough to warrant isolated to scattered thunderstorms in this same general area, with the best potential shifting eastward during the course of the day. Coverage will quickly decrease Tuesday evening with the departure of the cold front to the east. Some lingering northwest flow upslope isolated showers are possible across portions of southeast West Virginia, neighboring counties of southwest Virginia, and south into the Northern Mountains of North Carolina. Coverage will be greatest during the evening hours with decreasing coverage as the nigh progresses. Wednesday into Wednesday night, an upper level shortwave ridge is progged to build over the area, all while surface high pressure noses south along the lee of the Appalachians. Look for any lingering isolated showers in the west to end by noon. Limited cloud cover is forecast for all of the region by Wednesday afternoon. As Wednesday night progresses, low level flow on the west side of the surface ridge will allow for moisture levels to increase. Anticipate increasing cloud cover, and eventually some patchy light rain across areas mainly near the crest of the Blue Ridge from roughly Roanoke, VA southwest into the Northern Mountains of North Carolina. Temperatures during this portion of the forecast will trend from roughly fifteen degrees above normal Monday night into Tuesday to around five to ten degrees above normal Wednesday into Wednesday night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 300 PM EDT Sunday... The lee side ridge of surface high pressure will continue to prevail on Thursday, although low level flow not too far above the surface will start to increase as a closed upper low heads eastward through the central U.S. Look for light rain to increase across the area on Thursday, especially western and central parts of the region. The activity will take on more of a showery nature Thursday night as the upper system draws closer. On Friday, showers will be likely across most of the region with isolated thunderstorm possible across the western and southern parts of the area. The main system will track north of the area Friday night into Saturday, with its associated cold front across our region early Friday night. Look for an end of the shower activity for much of the area by Saturday morning. Lingering upslope showers on the backside of the system will be possible across southeast West Virginia and neighboring counties of southwest Virginia. Saturday night into Sunday, an upper level ridge will build over the area, allowing for a gradual decrease in the upslope showers in the west, and limited cloud cover in the east. Temperatures during this portion of the forecast will be around or slightly above normal Thursday and Friday, but trend to readings about ten degrees above normal for Saturday and Sunday. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 710 PM EDT Sunday... VFR to VFR/MVFR presently across most of the terminals, and those conditions should continue through the next couple of hours. Of note is lower, more widespread MVFR ceilings along the southern Blue Ridge and into the NC mountains that will contribute to obscured mountains through much of the TAF period. Ongoing unrestricted showers from Roanoke and Lynchburg south to Danville and Reidsville should persist next couple of hours as well. Limited potential for in-cloud lightning in southeast WV next couple hours, but not expected to affect any TAF. Confidence in ceilings is low for the rest of the overnight, but expect OVC VFR to MVFR to be the primary ceiling conditions for the terminals. Generally reflected this uncertainty with a second SCT MVFR cloud group. Light south to southeast winds overnight. For Monday...ceilings should begin to become scattered to broken again. Potential for showers and thunderstorms again for tomorrow, though would tend to be sporadic/intermittent. Winds stay southerly around 6-10 kts. Extended Aviation Discussion... An active weather period with a series of vigorous upper-level low pressure areas tracking from west to east across the U.S. during the week. Areas of sub-VFR cigs/vsbys are possible, especially during the morning hours, in low clouds and fog. Coverage of showers and thunderstorms will be the greatest during the afternoon and evening coinciding with the peak heating of the day. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM NEAR TERM...AL/PM SHORT TERM...DS LONG TERM...DS AVIATION...AL/PM