Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/18/17

Area Forecast Discussion
National Weather Service Buffalo NY
925 PM EST Tue Jan 17 2017 .SYNOPSIS... Low pressure will track across Lake Ontario and into the Saint Lawrence Valley overnight through Wednesday. This will result in some rain showers in most areas, with some mixed precipitation across the North Country. It will remain mild through the remainder of the week, with even warmer air reaching the region this weekend. && .NEAR TERM /THROUGH WEDNESDAY/... Low pressure across Western Lake Ontario this evening will track toward the Saint Lawrence Valley overnight. Steady precipitation across the North Country will exit the region late this evening, however there will still be showers and some drizzle lingering behind the system overnight. Based on the low track, winds should remain northeast in areas located north of Watertown which should keep surface temperatures near freezing for much of Lewis and northern portions of Jefferson county. This will result in a mixed bag of precipitation overnight, with a continued risk for freezing rain lasting much of the night. Thermal profiles aloft will cool late tonight, with precipitation trending toward rain or snow showers late. Elsewhere surface temperatures will be warm enough for precipitation to fall as all rain. The surface low will generate some lift, followed by a shortwave later in the night. Mesoscale guidance keys more on upslope precipitation, with areas of drizzle possible between the showers. Winds have shifted to the southwest across western portions of the cwa, advecting moist boundary layer air which is interacting with the relatively cool lake waters and then is getting trapped beneath an inversion. This is resulting in areas of fog, which is best captured by HRRR guidance. This fog will likely persist through much of the night, then spread into the Eastern Lake Ontario region late tonight before gradually diminishing Wednesday morning. A passing upper level wave will interact with the low level moisture to create a chance of rain in the morning, but conditions will improve by the afternoon, even though skies will remain cloudy. High temperatures on Wednesday will be in the middle to upper 30s. && .SHORT TERM /WEDNESDAY NIGHT THROUGH SATURDAY NIGHT/... Where has winter gone? The blame can be placed on the shoulders of a closed low anchored over Alaska and an anomalously strong tropical ridge over the Hawaiian Islands whose combined efforts will direct a very strong east Asian jet into the west coast of the country. This pattern will continue to flood the majority of the continent with Pacific modified air during this period...with temperatures over the Lower Great Lakes region averaging some 15 deg F above normal mid January standards. It is basically an extended version of a January thaw. Several robust shortwaves within the powerful zonal flow over the Pacific will slam into the west coast during this period...and this will lead to broad troughiness over the western half of the country while downstream ridging will amplify over the Great Lakes and eastern Canada. The warmth from such a pattern will be welcomed by many...but the inevitable downside to this is will be a significant rain event in the long term period. In the meantime... General ridging will be found over the Lower Great Lakes Wednesday night. While this will provide fair dry weather for the bulk of the forecast area...the passage of a shortwave across the North Country will be enough to warrant the maintaining low chc pops for that region. In terms of p-type...H85 temps in the vcnty of -2 to -4c will offer the chance for either rain or wet snow showers. Fair dry weather can be expected Thursday and Thursday ridging will amplify over the Lower Great Lakes. This will be accompanied by some weak warm advection with temperatures Thursday afternoon climbing to within a few degrees of 40 over the western counties. A little more cloudiness over the eastern Lake Ontario region will likely keep that area in the 30s. On Friday...the axis of a sharp negatively tilted ridge will extend directly across our forecast area while a companion negatively tilted trough will approach from the Upper Ohio Valley. Clouds will advance across the far southwestern counties ahead of the weakening trough...otherwise partly sunny skies will prevail with afternoon temperatures climbing well into the 40s. The anemic trough will continue to weaken as it will push northeast across our forecast area Friday night and Saturday. Weak convergence along this mid level boundary will be accompanied by a relatively narrow band of while there will be the low chc for a bit of light rain (or ZR for parts of Finger Lakes/North Country)... the vast majority of the time should be pcpn free. Temperatures will fall back into the low to mid 30s Friday night before climbing back into the mid 40s on Saturday. && .LONG TERM /SUNDAY THROUGH TUESDAY/... A progressive...yet highly amplified upper level pattern will be found across the country during this period...with the Great Lakes region being dominated by mild Pacific modified air. While this will mean that temperatures will remain well above normal...the period will be highlighted by what could be a soaking to problematic rain on Monday into early Tuesday. More on this in a moment. A ridge axis over eastern New York will support one more fairly nice day across our forecast area on Sunday...although clouds will likely prevail across the western counties. Temperatures will be some 15 deg F above normal values...with highs ranging from the upper 40s across the far western counties to the lower 40s on the Tug Hill plateau. The fair weather will deteriorate Sunday night as a deep stacked low over the Deep South will start to work its way up the western slopes of the Appalachians. Ahead of this very dynamic system...a plume of sub tropical moisture will stream northward from the Caribbean and Gulf stream of the western Atlantic to Virginia and Pennsylvania. As the leading edge of this moisture will make its way across our western counties late Sunday will be lifted by a strongly divergent upper level flow. This will start the process whereby our region could pick up a soaking rain. On Monday...the vertically stacked storm system will slowly drift north across the Upper Ohio Valley while the plume of sub tropical moisture off the Atlantic will edge over our region. This will lead to some widespread rain for our forecast area Monday and Monday night. The highest risk for significant rains will be east of the Finger Lakes. Guidance continues to suggest that this storm system will also support strong...potentially damaging...downslope winds between Lake Erie and the Chautauqua Ridge. A southeast low level jet of 50-55 knots just above a staunch inversion is very similar to events that local research has shown to be problematic. Stay tuned. The slow moving storm system is forecast to cross Pennsylvania on Tuesday while its plume of moisture will push across far eastern New York into New England. Meanwhile..drier air in the mid levels will advect across the western counties on Tuesday with dynamics weakening considerably in the process. This will lead to a tapering off of the rain from east to east. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Low pressure will track near Lake Ontario this evening. Southwesterly winds will advect moist air into the boundary layer resulting in low cigs and fog. This will result in LIFR or lower CIGs at BUF/IAG/JHW, with a potential for a period of dense fog. This has the potential to lower vsby to 1/4SM at times in BUF/IAG, with increasing winds possibly providing enough mixing to keep vsby in the 1/2SM - 1SM range. Poor conditions should continue through at least midnight, with gradually improving conditions likely late tonight as slightly drier air moves in. There still should be plenty of moisture remaining trapped beneath an inversion to result in widespread IFR-MVFR cigs which will last most of the day Wednesday. There will also be periods of showers and drizzle as another weak disturbances crosses the area late tonight. Showers will taper off from west to east Wednesday. Outlook... Wednesday night through Friday...Mainly VFR. Friday night and Saturday...chance of rain and some MVFR/IFR. Sunday...VFR. && .MARINE... Surface temperatures are not cold enough to enhance mixing, but winds have picked up across Eastern Lake Erie early this evening. This is the likely result of winds funnelling off the Chautauqua Ridge. Because of this, have issued a brief SCA for Lake Erie until WSW 925mb winds are progged to diminish early Wednesday. Wednesday will be another close call, with winds/waves expected to come close to SCA criteria on Lake Ontario. After this, a modest southwesterly flow is expected persist through Thursday with light winds Friday as high pressure ridges across the waters. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Weather Advisory until 4 AM EST Wednesday for NYZ007- 008. MARINE...Small Craft Advisory until 7 AM EST Wednesday for LEZ040-041. && $$ SYNOPSIS...APFFEL/WCH NEAR TERM...APFFEL/WCH SHORT TERM...RSH LONG TERM...RSH AVIATION...APFFEL MARINE...APFFEL
Area Forecast Discussion
National Weather Service Caribou ME
1102 PM EST Tue Jan 17 2017 .SYNOPSIS... High pressure will move east of the region overnight. Low pressure will pass well south of the state on Wednesday followed by an upper level disturbance crossing the region from Quebec on Thursday. High pressure will then rebuild over the region for Friday and the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... 1100 PM Update... Brought more clouds across the western areas overnight using the latest RAP and IR satl imagery. Temps in the low lying areas across northern and western Maine have dropped below zero. Further s where clouds have moved in, temps look like they have leveled off. Decided to lower temps a few degrees across the low lying areas of the n and w. Stayed w/the daycrew`s thinking on snow chances overnight into early Wednesday. Previous Discussion... High pressure to our north will continue to slowly move east toward New Foundland overnight. Meanwhile, low pressure will approach from the west, as a secondary low develops east of the New Jersey coast. With the secondary low passing well to our south and low level dry air in place, any snow will be confined mainly to central and downeast areas late tonight into early Wednesday. Any snow accumulation will be less than an inch overnight. Across northern areas, it will remain dry as low level dry air remains across the region associated with the high to our north. There will be a wide range in temperatures overnight as more in the way of thicker cloud cover across central and down east areas keep temperatures from falling too much, with lows here generally in the mid to upper teens. However, across far northern areas skies will remain mainly clear well into tonight and allow for decent radiational cooling where low temperatures will range from the single digits above zero to single digits below zero. Weak low pressure will continue to move east of the New Jersey coast and out to sea on Wednesday, as any light snow across central and downeast tapers to scattered snow showers by afternoon, with little in the way of accumulation. Across the north, high pressure will continue to ridge across the area from the northeast with dry conditions expected. High temperatures on Wednesday will range from the lower 20s north and mid 20s to near 30 downeast. Our focus will then turn to a weak weather system approaching from the northwest later Wednesday night. This system has the potential to bring a period of snow to mainly northern and central areas Wednesday night. There is the potential to bring an inch or two of snow mainly from the Katahdin region north. Lows Wednesday nigh twill range from the mid to upper teens north and upper teens to lower 20s downeast. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... Whats left of steady lgt snfl or sn shwrs across spcly Nrn ptns of the region Thu morn will exit the FA by aftn withe max totals potentially reaching 2 to 3 inches across the far N with progressively lesser totals Swrd toward the Downeast coast. Following the exit of this system, hi pres at the sfc and alf will re-build ovr the region Thu ngt thru Fri, briefly interrupted by some cldnss and possible flurries ovr the region late Fri into Fri ngt from a weak and fast movg s/wv from Cntrl QB. && .LONG TERM /SATURDAY THROUGH TUESDAY/... The entire long term looks dry and very mild as hi pres both at the sfc and alf builds ovr QB and Nrn New Eng. This pattern is part of an negative TNH teleconnection pattern durg this tm frame, which will keep fresh arctic air well NW of ern Can and splits the stm track N and S of the region. Uncertainty exits to when exactly this pattern begins to break down, but suffice it to say for now, the next chc of any sig precip will likely hold off to at least nearly mid week. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR conditions are expected tonight through Wednesday for the northern terminals (KFVE/KCAR/KPQI/KHUL). VFR can be expected through midnight at KBGR/KBHB. MVFR conditions are then expected late tonight and into Wednesday in any light snow or snow showers. SHORT TO LONG TERM: Thu will begin with IFR or low MVFR clgs/vsbys in sn across the TAF sites durg the morn hrs, improving to VFR clgs Downeast by Thu ngt and to high MVFR clgs Nrn TAF sites. All TAF sites will then be VFR by Fri...contg so thru the weekend. && .MARINE... NEAR TERM: Wind/seas will gradually increase to small craft advisory levels late tonight and continue through Wednesday. Have cancelled the small craft advisory for the intra-coastal zone and also delayed the onset of the advisory until 4 am. SHORT TO LONG TERM: No hdlns xpctd attm for these ptns of the marine fcst attm. Wv hts, which will begin just below min SCA thresholds on Thu, will gradually subside to 1 to 2 ft as sfc hi pres settles ovr the region with wv pds arnd 9 to 10 sec. Kept close to WW3 wv guidance for fcst wv hts. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory from 4 AM to 7 PM EST Wednesday for ANZ050-051. && $$ Near Term...Hewitt
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
836 PM CST Tue Jan 17 2017 .DISCUSSION... Made a few changes on the forecast for the first and second periods based on radar trends, RUC/GFSLAMP model output and HRRR model trends. In a nutshell, looks like the boundary is sinking a bit south but will go only a bit more. Most of the convection has been out west and adjusted rain chances up there (and lowered them southeast this evening), then kept pretty much the same POPs after 06Z but did bring the rain over the eastern areas a bit later (broke up weather grid). Lots of weather in the grids between 09Z and 15Z including rain with isolated thunder, patchy and areas of fog. Based on model temperature output, adjusted min/max grid accordingly using Min/Max tools (adjusting min temp down a degree and the max temp grid up a degree). Midshift can handle the changes for Wednesday as-needed. Always a tough temperature forecast with a stalled front in the area. Product updates have been issued. Any changes to the marine grids were to the weather and subtle changes to the afternoon winds on Wednesday. && .PREVIOUS DISCUSSION... /Issued 629 PM CST Tue Jan 17 2017/ DISCUSSION... See MARINE and AVIATION discussion for update on marine and 00Z TAFS, respectively. MARINE... Fog is starting to develop over the bays and nearshore waters as seen by web cams. For now, will handle it with MWS as RUC13 soundings indicate some of the heavier fog/VSBYS may improve a bit overnight. Will monitor conditions but did mention that if fog becomes more dense than a Dense Fog Advisory will be needed/issued. MWS and CWF have been issued/updated. AVIATION... Most of the convection has been showery with not much thunder and think this trend will continue for KVCT, KALI and KCRP. However, there will be a better chance for thunder at KLRD starting around 04Z and continuing until around 09Z (have VCTS/TEMPO TSRA) as jet streak moves across the region. Farther east, I believe the forcing will mainly be frontal with not as much large scale lift so will continue with showers, with most of the showers overnight and before 15Z. Tricky one is KVCT where they could be close enough to the larger scale lift to warrant some thunder (so did include a TEMPO toward 12Z). Rain chances will diminish much at KLRD after 15Z, with clearing late with drier NW winds coming in (have going VFR by 20Z). Farther east, more chances for showers in the morning, with the showers shifting more to the coast during the afternoon as the winds gradually shift more westerly. This will help CIGS to improve but only MVFR during the afternoon. Before 12Z will have LIFR conditions mainly due to cigs but could also have some VSBYs 2SM or less. Lots of things to consider, but overall this is the scenario so see the individual terminal forecasts for more precise station information. PREVIOUS DISCUSSION... /Issued 344 PM CST Tue Jan 17 2017/ SHORT TERM (Tonight through Wednesday night)... Chances for showers and thunderstorms will continue through the short term. A cold front currently extends from Victoria back westward and west southwestward to south of Cotulla. Isolated convection (mainly showers) this afternoon will move northward across the area this afternoon. The frontal boundary will remain stalled across the area this evening into Wednesday. This will set the stage for additional showers and thunderstorms across South Texas. Despite limited instability, shear will be sufficient enough for strong thunderstorms. A few storms could become severe though with strong winds and a brief spin-up may be possible with a storm that interacts with the boundary. Elevated convection north of the boundary from the northern Brush Country into the Victoria Crossroads could pose a marginally severe threat. SPC maintains a marginal risk of severe storms over the area late this evening into tonight. Also, a threat for moderate to heavy rain at times will as deep moisture (PWs 1.5 to 1.6) will pool along and north of boundary. Latest guidance brings the front closer the Middle Texas Coast on Wednesday. This will favor chances for showers and storms continuing across the eastern and northeastern parts of the area on Wednesday. Slight drier air will move into the Rio Grande Plains which will diminish rain chances somewhat across the west tomorrow. High temperatures will be tricky with the front draped across the area. Temps should generally range from the mid/upper 60s across the Rio Grande Plains, northern Brush Country, and Victoria Crossroads to lower and mid 70s across the Coastal Bend. One last round of convection will be possible Wednesday night into early Thursday morning as main upper trough axis approaches from the west. LONG TERM (Thursday through Tuesday)... Convection Thursday should be confined to the morning hours and primarily across the coastal counties and offshore. Parent trough axis is prog to shift east across the CWA around midday with significantly drier airmass throughout the entire atmospheric column developing in the afternoon. Result should be clearing skies from west to east through the day. Moisture quickly tries to build back northward on Friday in the sfc-H8 layer with an increase in cloud cover expected during the day across mainly the eastern half of S TX. Another mid/upper level trough is prog to approach the region Friday afternoon and if enough moisture can advect north through the day...then an isolated shower or thunderstorm may occur in the afternoon. For now...will carry only 20 POPs across the coastal areas and offshore where best moisture depth is prog to occur. Wind profile from the surface through H2 is prog to become more WSW by Saturday and result in warm adiabatic flow through the day. Max temps Saturday may be the warmest of the extended forecast with most inland locations warming well into the 80s /isolated upper 80s possible/. Strong cyclogenesis is prog to occur Saturday night across the TX Panhandle with a 991mb low hooking and kicking ENE over N TX...and sending a Pacific cold front across the region. Storm system is prog to become stacked over N TX through the day Sunday with potential existing for a strong wind event across South Texas. Strong mixing of adiabatic processes...with H85 wind speeds prog to be around 50kts nearly areawide...could result in widespread strong sfc winds during the day Sunday. Guidance`s placement of synoptic features strongly correlates to some of the stronger non convective wind events across South Texas. If current forecast pans out...wind advisories and/or high wind warnings may be required Sunday...along with red flag fire weather conditions. System kicks east early next week with mid/upper level ridging building into the region along with continued dry conditions and another significant warming trend. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 66 69 57 75 59 / 60 60 50 30 0 Victoria 60 65 56 73 56 / 90 80 50 20 0 Laredo 56 63 55 78 57 / 70 30 30 10 0 Alice 63 67 56 77 56 / 70 50 50 10 0 Rockport 66 68 57 72 61 / 60 70 60 30 0 Cotulla 55 61 51 78 53 / 70 40 30 10 0 Kingsville 65 68 58 77 58 / 60 50 50 20 0 Navy Corpus 66 68 58 72 62 / 60 60 60 30 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ GW/86...SHORT TERM
National Weather Service Des Moines IA
530 PM CST Tue Jan 17 2017 .SHORT TERM.../Tonight through Wednesday/ Issued at 318 PM CST Tue Jan 17 2017 A welcome reprieve from the past few days, the main forecast attention now turns to fog and stratus trends rather than freezing rain. An impressive short wave/PV anomaly shows up nicely in the water vapor imagery this afternoon and any lingering mid level forcing should continue to push east away from Iowa this evening. The following low level cyclonic flow will weaken as well but the associated stratus and fog has been slow to dissipate, often slower than what models anticipated. The more recent HRRR and RAP reflect reality better and suggest the stratus will be slow to depart, and even if it does more fog should develop with weak return flow over the cold, icy ground in the ridge. Thus have added fog back into the forecast tonight, which could end up being dense in spots. The subsidence behind the system will likely reduce the depth of the low level moisture layer sufficiently to stop any drizzle however. The pattern and return flow into Wednesday will hopefully be progressive enough to scour out the low level moisture into Wednesday leading to some sunshine and melting. The new ice and old snow cover will reduce confidence in the degree of mixing and high temperatures however. Morning snow depth measurements still show several inches of icy snow across the north so have depicted somewhat of a north/south gradient just north of Highway 20 separating 30s and 40s. There is certainly the potential for 50s south with aggressive mixing but have not gone that highs as of yet with concern about lingering low level moisture and icing. .LONG TERM.../Wednesday night through Tuesday/ Issued at 318 PM CST Tue Jan 17 2017 An active weather pattern is still expected for the long term period with five upper-level shortwaves or closed lows progged to impact the CWA. Above normal temperatures are expected during the period. Highs are generally expected to range from the middle 30s to lower 50s, and lows are generally expected to range from the middle 20s to lower 40s. First feature will begin affecting the CWA during the day on Thursday as an upper-level low across the southwestern U.S. drifts northeastward toward the CWA. Ample low-level moisture is expected from this time period through the rest of the long term period. Forcing with this feature will be relatively light so have gone mainly slight chance POPs. This feature will be followed quickly by a shortwave associated with the upper-level low, and will traverse the CWA on Friday. Forcing and moisture will be more plentiful with this feature. There may be some light freezing rain across the northern CWA Thursday night into Friday before low-level temperatures warm enough for all liquid precipitation. Another shortwave quickly rotates around the upper-level low Friday night into Saturday, and will be associated with similar amounts of moisture and forcing. Either rain or snow, or a rain/snow mix are expected with this system with the best chances across the northwestern half of the CWA. Saturday looks to be the warmest day during the long term period. Saturday morning lows will range from the lower 30s across the north to the lower 40s across the southeast. Highs will range from the lower 40s across the northwest to possibly the middle 50s across the southeast. The fourth feature will be a shortwave rotating around a northern U.S. to southern U.S.shortwave from Sunday into Monday night. Mainly rain is expected, however either snow or a rain/snow mix is possible on the northwest edge of the precip shield Sunday night and Monday night. Fifth and final feature is an upper-level low progged to affect the CWA during the middle of next week. Precip chances are currently expected to increase during the day on Tuesday with mainly rain except for snow or rain/snow mix across the northern CWA on Tuesday night. && .AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/ Issued at 530 PM CST Tue Jan 17 2017 IFR or lower conditions will persist for most or all of the night across the forecast area. Satellite imagery indicates a back clearing edge progressing across western Iowa that may or may not stall out overnight with a surface ridge building into the area. However, even if skies do briefly clear across the north, low dewpoint depressions and saturated ground should quickly lead to fog and stratus redevelopment. Significant improvement is not expected until after sunrise Wednesday as winds come around to SSW and we burn off/mix out lingering fog and stratus. Thereafter, VFR conditions are forecast for tomorrow. && .HYDROLOGY... Issued at 318 PM CST Tue Jan 17 2017 Stream flows across the southeast three-quarters of Iowa is now generally above or much above normal for this time of year. Precipitation from the Sunday-Monday storm system has led to within-bank rises on streams, especially across the south where precipitation was seasonally heavy /i.e., 1 or more inches/ and significant within-bank rises resulted. Most of the precipitation became runoff because the frozen ground allowed for little if any infiltration. Although some break-up ice jams have already been reported with no flooding, additional break-up ice jams may occur within the next day or so due to additional runoff from the earlier precipitation. At worst, isolated minor flooding is expected, with most of the rises remaining within bank. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Small LONG TERM...Zogg AVIATION...Lee HYDROLOGY...Zogg
Area Forecast Discussion
National Weather Service Quad Cities IA IL
549 PM CST Tue Jan 17 2017 ...AVIATION UPDATE... .SYNOPSIS... Issued at 327 PM CST Tue Jan 17 2017 Upper level trough/cold pocket aloft over the dvn cwa providing a solid low stratus deck across much of the Midwest. There is an area of rain/snow mix in sw WI associated with a vort max and was dropping southward. The back (western) edge of the stratus extended from sw MN to the NE/IA border and into extreme eastern KS. This back edge was eroding slowly eastward as anti-cylonic flow/high pressure existed in the northern/central Plains. 3 pm temperatures in the cwa were in the 30s along with patchy fog. Elsewhere, temperatures from KS to TX were in the 40s and 50s. && .SHORT TERM...(This Evening through Wednesday) ISSUED AT 327 PM CST Tue Jan 17 2017 Forecast focus on cloud and temperature trends. Tonight: Will have 30 pops in our far north (along Highway 20) through early this evening as the edge of the area of rain/snow in WI grazes our far north. The HRRR pushes this east of the dvn cwa by 8 pm. Meanwhile, upper level trough/cyclonic flow will slowly push eastward as the night progresses. Therefore, for much of the night the low stratus/areas of fog will persist. Late tonight there should be some eroding of the cloud deck in our far western counties, as subsidence arrives. Minimum temperatures should range from the mid to upper 20s west to the lower 30s east. Have raised temperatures from previous forecast as the clouds linger longer than earlier thought. Wednesday: With anti-cyclonic flow/subsidence across the cwa skies should be mostly sunny for much of the day. However, east of the MS River the clouds may linger for a portion of the morning before eroding. During the afternoon a weak upper level low currently in the southern Rockies will be pushing into KS. This will return a southwest flow aloft/southerly surface winds to the cwa, ahead of this system. As a result, a warmer day is anticipated with highs in the 40s. .LONG TERM...(Wednesday Night through Tuesday) ISSUED AT 327 PM CST Tue Jan 17 2017 Wednesday night and Thursday...Light south to southeasterly llvl return flow Wed night between departing sfc ridge and a broad cut- off upper low portion of upstream Rex block acrs the plains, may make for non-diurnal temp curves into early Thu morning. Depending on cloud cover, there may be at least some patchy fog by Thu morning as sfc DPT/moisture advection increases. As the upper low is projected to roll out northeastward to the MO RVR Valley, The warm moist conveyor up off the western Gulf will be gathering strength up the eastern plains and toward the low/mid MS RVR Valley on Thu. Shower activity/Areas of rain will look to increase from the south acrs the area as Thu progresses...probably becoming more widespread Thu night locally as lift off the large upper low complex increases from the west/southwest. Current thermal profiles for that time period are mild enough to keep precip all rain into early Fri morning CWA-wide. With the sfc layer becoming saturated again along with areas of convergent east to northeasterly flow, fog may be an issue during lulls in rainfall from later Thu and into Thu night. Friday and Saturday...Both the 12z GFS and ECMWF pivot the lead wave in a opening up upper trof fashion, north of the CWA acrs MN and WI by Fri night. Thus the more organized precip should follow, waning acrs the local area Fri afternoon and evening. rainfall amounts from Thu to Fri may range from a quarter of an inch to over a half inch adding to run-off into the rivers and urban ponding of water. If low clouds persist, there may be lingering drizzle and some fog. Despite the cloud cover and saturated llvls, ambient temps to continue to be mild and well above normal Fri with highs in the mid to upper 40s, except north of Hwy 30 more in the way of lower 40s. Sunday through next Tuesday...Both the latest GFS and ECMWF suggest brunt of warm pull to be in full bore Sat east of the upper low as a nice bout of southwesterly flow engulfs the region. With a lull in any precip and some thinning in the overcast or some breaks, temps may be not all that far away from record highs for Jan 21st. But for now will play it more conservatively but still trend up a bit to upper 40s along Hwy 20, to the mid 50s south of I80. The latest run medium range models are varying on how far north the main cut-off upper low in the southern stream pulls out eastward acrs the central CONUS. The 12z GFS now rolls the vortex deeper acrs the lower MS RVR valley, and thus it`s Trowal feed of wrap around moisture misses most of the CWA to the south and east Sunday into Monday. The new 12z ECMWF is a bit further north, but still has it`s more significant precip to the south and southeast. But the Euro is also more bullish with an associated inverted trof complex that extends northward acrs the region and focuses some of the Trowal moisture in the form of rounds of rain showers Sunday into Monday. The ECMWF`s QPF fields also show much of the area getting over a half inch of rain in 24 Hrs, something area rivers and streams probably won`t need at that time. Then longer range indications suggest a trend back to cooler conditions(but still above normal) into early next week, behind what ever system pushes through the region during the Sun-Mon timeframe. The latest medium range models also suggest a mid next week cyclone acrs the midwest, but confidence that far out and how far north or south it tracks, is low to say the least at this point. ..12.. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) ISSUED AT 538 PM CST Tue Jan 17 2017 Trapped low level moisture will continue to bring mostly IFR conditions with possible episodes of lower end MVFR at the terminals into early to mid Wednesday morning. Westerly winds at 5 to 15 MPH tonight will shift to the southwest at 5 to 10 MPh on Wednesday will clearing skies by mid to late morning. && .HYDROLOGY... Issued at 327 PM CST Tue Jan 17 2017 With unseasonable January rainfall amounts and subsequent run-off, combined with ongoing ice action, flood warnings have been issued for all forecast points on the Rock River. Joslin was adjusted upward to moderate flood stage, with some historical events with similar precip/ice during this time of year suggesting very quick rises up close to major flood stage possible over the next few days. Moline on the Rock may be getting, or eventually will get some input from the ice jammed up waters of the lower Green River. On the Mississippi, some signs of the ice jam just south of Burlington starting to erode and allow flow through, such as some drops upstream at New Boston and well as rise slow downs or stalls at Gladstone and Burlington. The mild weather projected for the next several days, as well as some increase in stream flow from up north, should enhance ice erosion and eventually lead to the break up of the BRL ice jam. Both Gladstone(GLD) and Burlington(BRL) will have to be watched for sudden drops in their river levels over the next few days, signs suggesting that the jam finally is cutting loose. Recent rainfall/run-off combined with ice action also producing rises near or to flood stage at some sites on the Iowa and English River in Iowa. A few other Iowa rivers approaching action stage. And a localized areal flood warning ongoing west of the official forecast point of Geneseo IL on the Green River for a reported ice jam producing flooding. The rivers will have to be watched area-wide for more ice action and jams possibly producing additional flooding during the upcoming week of unseasonably mild weather. ..12.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...Flash Flood Watch until 9 PM CST this evening for Henry IL. MO...NONE. && $$ SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...12 AVIATION...Nichols HYDROLOGY...12
Area Forecast Discussion
National Weather Service Jackson MS
945 PM CST Tue Jan 17 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION... A stalled frontal boundary is currently located along the Natchez Trace Parkway beneath broad mid-level ridging. Shower activity today remain concentrated across the NW portion of the CWA where an estimated swath of 0.5 - 1 inches of rainfall has occurred over the last 12 hours. There were also a few isolated showers this afternoon across the SE, but QPE was much lighter and generally less than 0.1 inches. For the remainder of the overnight period, the pressure gradient is much more relaxed tonight compared to last night thus resulting in much calmer winds with boundary layer decoupling already underway at some locations in the SE portion of the forecast area. With a warm and moist airmass in place at the surface guidance has come in more aggressive with fog potential, some of which could be dense especially along the I-59 corridor. Therefore, went ahead and put a limited area in the HWO for fog along and SE of a line from Lawrence county to Meridian where patchy areas of fog with visibilities less than a quarter mile are possible. Otherwise, shower activity in the NW Delta will tend to become more scattered throughout the evening with QPF amounts remaining on the lighter side and less than a quarter inch. In regards to overnight min temps, went with a blend between raw guidance and MOS which resulted in a slight increase by a degree or two but nothing too drastic. /TW/ Prior discussion below: Mid level ridging will help relax the wind fields tonight leading to a reduction in the convective activity. With the loss of mid level support the frontal boundary will only ooze a little further south tonight before stalling and then begin to back up as a warm front Wednesday. With the calming winds, the HRRR is indicating the potential for some dense fog over the southeast. Cold core moving into the Plains will once again induce a mid level southwest flow regime with an increase in isentropic ascent, especially near the retreating warm front. Numerous showers will move in from the west during the afternoon as this occurs. A few thunderstorms will also be possible in the south as the warm sector destabilizes. /26/ Wednesday Night through Monday: Mild spring like anomalous conditions will continue through Sunday with a cool down for Sunday night through Monday night. During the period several strong storm systems will affect the region for Thursday as well as the weekend. The stronger system will be this weekend with the Large Hail Potential. For Wednesday night with mid to upper ridging around we will have a warm front to the north as a storm system approaches from the Southern Plains. Showers and some embedded thunderstorms will be continuing at that time. Local heavy rainfall potential is expected to develop in the western delta late Wednesday night on the approach of Thursday`s storm system. This will be aided by a low level gulf inflow jet of around 35 knots. The active southern stream will pivot a negatively tilted upper trough from the southern plains tracking into the region for Thursday into Thursday night. There will be enough lift, moisture transport convergence(pwats around 1.6), instability, and deep layer shear for some locally heavy rainfall and some severe weather risk along with some risk of hail. For right now its looking to be a low end severe risk. The primary risks will be locally heavy rainfall, damaging wind gusts with a few severe storms, and a tornado will be possible.Model guidance has from one to three inches of qpf. With the progressive nature of this system not looking for any major heavy rain risk. This system will exit the region by late Thursday night. So with the dynamics of this system opted to put the whole region under a limited risk of severe weather and possible tornado. Took out the limited flooding risk. There will be a lull between systems on Friday as the next stronger system develops over the Southern Plains. This deep closed system will move over the region for Saturday into Sunday. The primary concern with this stronger system will be the Large Hail Potential with such a closed cold core system. There will be multiple waves of all modes of severe weather during the weekend period. The primary risk of concern will be Large Hail Potential. Models have been showing that potential for the last few days with projected hail sizes greater than golfball. This is supported by 8c midlevel lapse rates and vertical totals in the lower 30s. The other risks will be Damaging Winds, and a few tornadoes. Be sure to stay tune for updates. If the models remain consistent in future runs we will be increasing the Threat Risk in our graphics and HWO for this system, which has the potential of becoming a significant severe weather event. The system is expected to exit the region by Sunday night. Looking ahead toward the middle of the upcoming work week mild conditions will be come back once again with a front passing through mid week for another chance of rain. /17/ && .AVIATION... 00Z TAF discussion: A band of -shra nw of a line from HEZ-CBM wl cont this evng while only an isold -shra or two wl occur se of the line. A stalled cold front pushed through HKS-JAN at 23z but wl remain ne of MEI this evng. IFR cigs were observed at GLH and GWO at 23Z with VFR conditions elsewhere. IFR conditions will increase as low clouds and fog develop later tonight. LIFR conditions will develop once again at HBG as the fog becomes locally dense. Conditions wl slowly improve to VFR Wed morning but a greater coverage of shra/tsra wl lower flight categories at times through wed evng. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 60 71 63 69 / 21 39 53 93 Meridian 61 72 61 70 / 10 25 36 89 Vicksburg 56 69 63 69 / 30 57 70 93 Hattiesburg 63 74 63 72 / 16 26 29 83 Natchez 61 72 64 70 / 12 54 65 93 Greenville 50 60 57 65 / 72 69 78 89 Greenwood 53 64 61 68 / 86 53 68 92 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ TW/17/22/26
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
934 PM CST Tue Jan 17 2017 .UPDATE... Issued at 920 PM CST Tue Jan 17 2017 Slowed down the clearing a little, and raised the minimum temperatures for tonight a tad across southeast MO and southwest IL. Clearing line is advancing slowly across parts of northwest and west central MO this evening. The model guidance continues to show clearing of stratus cloud deck from west to east tonight, but satellite trends appear to indicate the clearing may be a little slower than previously forecast. There will likely be some patchy fog late tonight in areas that clear out with surface winds becoming light underneath the surface ridge axis. Lows tonight will be cooler than the previous night, but still about 10 to 15 degrees above normal. GKS && .SHORT TERM... (Through Late Wednesday Afternoon) Issued at 324 PM CST Tue Jan 17 2017 Skies have remained cloudy this afternoon as low level moisture remains trapped under an inversion. Latest regional satellite does show that the clearing line is currently over far eastern Kansas. RAP low level progs suggest that drier air will work into the area during the late evening and overnight hours allowing low clouds to erode. This will be about the same time a surface ridge will move into the area causing the winds to turn light allowing some patchy fog to form, particularly across central Missouri where the clearing will occur first. This fog will remain over the area into the morning hours before it burns off by mid morning. Should see more sun on Wednesday as a shortwave ridge moves across the area. More clouds will move into southeast Missouri late in the day as mid-high level moisture streams northeastward ahead of an upper low in the Southern High Plains. Lows tonight will not fall much with the clouds staying in most of the night. Went with a compromise of MOS guidance for low tonight. With sunshine tomorrow and winds turning out of the south, highs will once again be close to the agreeable MOS highs. Glass .LONG TERM... (Wednesday Night through Next Tuesday) Issued at 324 PM CST Tue Jan 17 2017 The models remain in relatively good agreement with the large scale mass fields this cycle depicting a stout ULJ emanating from the Pacific and contributing to an energetic lower latitude storm track. The upper low currently over the southwestern U.S. will lift northeast into the central Plains Wednesday afternoon/night. Then the main upper low takes a more northerly track as a strong negatively-tilted short wave rotates around it and thru the Lower and Mid MS Valley region Thursday afternoon/night. The models while still showing some differences with respect to QPF with this system, have trended closer and generally all show more backed low and mid level flow. This results in a faster and more westward shift of the warm conveyor belt and associated moisture transport, beginning on Wednesday night and increasing on Thursday. The combination of large scale ascent and the moisture transport on Thursday will correspondingly lead to greater coverage and northward/westward extent of precipitation. Moderately steep mid level lapse rates will also support a threat of at least isolated thunderstorms. Friday and Friday night look dry in the wake of this departing first system. Another upper low and trof will lift north/northeastward from the southern/central Rockies and through the central U.S. Friday night and Saturday morning bringing deepening south/southwest flow aloft. The are some decent height falls and weak large scale forcing for ascent on Saturday. Moisture however seems pretty minimal in the wake of the previous system and a bit low for much in the way of any decent precipitation threat. The eye-catching system is still on track to impact the region late Saturday night-Monday as a potent upper low tracks across the southern Plains and across the lower/mid MS Valley. The guidance has all shifted south with this system and present indications the main impact would be for the southern/southeast 2/3rds of the CWA with a good rain event. Mild, above average to well above average, temperatures will prevail thru the forecast period. Glass && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 558 PM CST Tue Jan 17 2017 Ridge of high pressure over western MO will move eastward through our area later tonight and Wednesday morning. Stratus cloud deck around 1000 feet in height will continue this evening, but clearing line over the KS MO border was advancing slowly eastward. Model guidance continues to shift the clearing line eastward tonight and Wednesday, although there is still some uncertainty with the timing of the clearing, especially during the overnight hours. For now will scatter out the low level cloud ceiling in COU at 05Z, UIN at 11Z, and in the St Louis metro area at 10-11Z. At least light fog will develop late tonight, especially where it clears out well before sunrise. Westerly surface winds will back around to a south-southwest direction Wednesday morning as the surface ridge shifts east of our area. SPECIFICS FOR KSTL: Ridge of high pressure over western MO will move eastward through our area later tonight and Wednesday morning. Stratus cloud deck around 1000 feet in height will continue this evening, but clearing line over the KS MO border was advancing slowly eastward. Model guidance continues to shift the clearing line eastward tonight and Wednesday, although there is still some uncertainty with the timing of the clearing, especially during the overnight hours. For now will scatter out the low level cloud ceiling in STL at 10Z. Some light fog will develop shortly after it scatters out. Westerly surface winds will back around to a south-southwest direction Wednesday morning as the surface ridge shifts east of our area. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
827 PM CST Tue Jan 17 2017 .UPDATE... It is appearing increasingly likely that we will see some pockets of fog, potentially dense, develop late tonight. The best window will be after 09Z as precipitation diminishes and shifts northeastward. The moist ground, near saturated low-levels, and tendency toward clearing skies will combine to provide favorable conditions for fog development. Coverage and density of fog remains somewhat uncertain but the NAM, RAP and HRRR do show pockets of dense fog in the region early Wednesday. Any fog should diminish by mid-late morning, with mostly sunny skies and quickly warming temperatures Wednesday afternoon. Before then, we have added areas of dense fog for much of the area from 09Z to 16Z. Additionally, the rain chances were decreased to slight chance and chance levels in the 09Z-12Z as the last bit of lift quickly fades. No other adjustments were made to the forecast at this time. The updated products have been sent. && .PREV DISCUSSION... /issued 539 PM CST Tue Jan 17 2017/ AVIATION... Showers continue to increase and spread north toward terminals so included them in prevailing conditions at onset. Initially kept VFR conditions, though any heavier showers directly affecting terminals will likely carry MVFR ceilings for a while. Main degradation comes late this evening as stratus deck develops during period of enhanced low level lift as shortwave passes to the west. In the wake of the disturbance, sufficient subsidence is noted with calm winds allowing favorable cooling for surface- based fog to form. With reasonable confidence and agreement among short range guidance have included IFR/LIFR cigs at KLBB around sunrise with IFR at PVW and KCDS. Increasing southwesterly component to wind should scour moisture by late morning. PREV DISCUSSION... /issued 330 PM CST Tue Jan 17 2017/ SHORT TERM... Low clouds across parts of the area cleared fairly fast this morning only to be replaced by mid-level clouds increasing from the south, mainly along and east of the Caprock. Radar has been showing reflectivity values increasing mainly just to the south of our area of responsibility and West Texas Mesonet sites also show that the only places seeing rain reaching the ground are in the areas of 45+ dBZ reflectivity. Fairly dry boundary layer is preventing much of the precipitation from reaching the ground outside of the heavier areas of rainfall. This current precip will help to moisten the atmosphere up ahead of the next storm system which was located over southern AZ/NM and was slowly moving east. A shortwave will kick out overnight tonight across the area which will help to further increase coverage of precipitation across the area, roughly from around sunset through the mid early-morning hours/before sunrise Wednesday. Models are starting to shift the area of greatest coverage/intensity into the Rolling Plains but the NAM and GFS still hint at another area of locally heavier precip near the TX/NM state line. Where the greatest amounts will fall will depend on how strong the shortwave will be and where the best lift will move as well. Forecast soundings across the area show that there will also be a narrow window where meager elevated instability will develop as the shortwave helps cool the middle of the column. This combined with the increasing lift may be enough to generate a few thunderstorms mainly between sunset and roughly midnight to 1 am before the shortwave is north of the area. Lastly, surface temperatures look to remain well above freezing during the precipitation event so precip should remain liquid. Once precipitation has shifted northward by sunrise Wednesday, there could be enough clearing mainly across the southern South Plains to allow temperatures to drop into the low to mid 30s but do not anticipate any problems if temps fall below freezing in a few spots due to short amount of time. The rest of the area will remain in the upper 30s to lower 40s. The main low will continue to slowly move northeast with the center pushing into southeast Colorado by Wednesday morning with a trailing, positively tilted trough extending southwest into Mexico. This will result in southwesterly flow aloft and at the surface which should help clear out any cloud cover and precipitation by sunrise. Only uncertainty is how much high cloud cover may be pulled ahead of the trough axis and that could impact high temperatures Wednesday afternoon a bit. Jordan LONG TERM... The first of several troughs to impact our region over the next week will be lifting to the northwest into Oklahoma and Kansas on Thursday. Dry air will rapidly work its way in thanks to strong west/southwesterly winds, which will also help to boost highs that afternoon. Winds that day will seem but a mild breeze compared to the upcoming days, though. As shortwave ridging sweeps overhead Thursday night, winds die down, but by Friday morning, the impacts of the next upper level trough will be felt in the form of increasing wind. This particular trough will swing by to our north, pushing a tight pressure gradient across the region and bringing us a Friday afternoon that could come close to wind advisory criteria. As the progressive pattern continues, we`ll see our next trough the very next day. This one may have the chance of bringing us precipitation...along with more wind. The mid to upper levels look fairly well saturated for Saturday afternoon and night, however, with a dry surface and decent westerly winds, precipitation may be fighting to make it to the ground. As this low deepens and moves eastward, it will drag a cold front through on Sunday...with more wind. Looking ahead to next week at the very end of the period, yet one more low begins to swipe the region...and yes, with wind. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 24/23
Area Forecast Discussion
National Weather Service Mobile AL
958 PM CST Tue Jan 17 2017 .DISCUSSION...See updated information for land areas below. && .UPDATE...Visibilities have dropped over the current advisory area. Am evaluating on timing of expanding it inland. With some reports dropping inland, am expecting this to occur soon. /16 && .PREV DISCUSSION... /issued 609 PM CST Tue Jan 17 2017/ DISCUSSION...Updated for latest aviation discussion below. AVIATION... 00Z issuance... IFR Conditions are expected to dominate tonight with instances of LIFR and VLIFR after midnight. Dense fog is anticipated to form in our inland and coastal areas after midnight and will remain in place until well after sunrise. High clouds and westerly winds above 25kft will move-in in the early morning hours. Surface winds are expected to remain out of the south for the duration of the forecast period. 17/DJ PREV DISCUSSION... /issued 408 PM CST Tue Jan 17 2017/ NEAR TERM /Now Through Wednesday/...17.12Z upper air map analysis shows an amplified deep layer ridge positioned over the northwest Caribbean and the southern Gulf. To the west and north of this ridge, a tap of east Pacific moisture is seen in satellite imagery streaming northeast across northern Mexico into the southeastern US within a well established high level southwest flow. At the surface, a cold front was draped from the Ohio River Valley to the upper Texas coast. As a frontal wave of low pressure lifts northeast across the Great Lakes, the southwest portion of the front is beginning to stall over the Texas coast. An assessment of deep layer moisture (pwat values) east of the frontal zone shows values from near 1 inch over northern Alabama to around 1.4 inches over the lower Texas coast. From a climatological perspective, these values are near 180% of normal. Within this zone, radar shows pop-up isolated showers lifting off to the northeast at 10 to 15 mph. After sunset, the high resolution guidance tapers off coverage. Even so, could still be a very isolated shower passing over any one area and feel a 10% chance will effectively cover this. The placement of the synoptic scale surface high to the east and the front to our west favors the development of night-time fog. The high resolution HRRR, NAM12, RAP and MOS guidance all show this, with fog forming over the southern zones this evening and spreading northward over the interior. The short range ensembles also indicate elevated probabilities (70%+) of fog by midnight over the southern zones (restrictions to visibility dropping off to 1 mile or less). Considering the convergence amongst all the guidance leading to higher forecaster confidence, a dense fog advisory will be issued on the 4 pm package beginning at 8 PM and continuing into shortly after daybreak Wednesday. Upon monitoring trends this evening, the advisory may be extended northward. After fog lifts on Wednesday, a small chance of showers possible thru the day. As for temperatures, no changes with night-time lows and daytime highs on Wednesday being well above climatic normals. /10 SHORT TERM /Wednesday night Through Friday night/...Upper ridging extending from the southeast Gulf of Mexico to the lower Great Lakes will continue to get pushed to the east as an upper level low pressure area central plains lifts northward. An upper trough extending southward from the closed low to northeast Mexico around noon Thursday will swing northeastward, becoming negatively tilted as it passes very quickly over the region Thursday night. Upper ridging will then rebuild over the southeast conus on Friday as the upper trough continues to move northeast away from the area. Weak surface high pressure will remain across the region through midweek, and then move east of the area as a weak surface low forming across the Arklatex region on Thursday lifts northeast to near Chicago by late Thursday night. Weak surface high pressure will rebuild across the forecast area on Friday. A dry forecast is expected through Wednesday evening, with patchy fog forming across the forecast area once again. Isolated to scattered coverage of rain showers will move into the forecast area northwest of I-65 after midnight, followed by likely to definite showers and thunderstorms spreading east across the forecast area throughout the day Thursday as the upper trough swing quickly over the region. A few strong to marginal severe thunderstorms with gusty surface winds may accompany the line of storms Thursday afternoon and evening as a low level jet between 40 to 50 knots passes over the forecast area. Much of the rain will end from west to east after midnight, with only isolated rain showers occurring throughout the day Friday. High temperatures both Thursday and Friday will continue to be warm, ranging from 71 to 76 degrees. Low temperatures each night range from the mid 50s to lower 60s. /22 LONG TERM /Saturday Through Tuesday/...A second upper closed low is expected to form over north Texas by Saturday evening and move east over northern Mississippi by midnight Sunday night. An associated surface low pressure area forming across the Texas Panhandle is expected to strengthen as it moves east, reaching Tennessee during the same time frame. This will set up another very wet pattern across our region, with scattered to numerous showers and a chance of thunderstorms through the weekend, with widespread rainfall amounts between 2 to 3 inches. A few strong to marginal severe thunderstorms with gusty surface winds may accompany the line of storms Saturday into Sunday as a low level jet between 40 to 50 knots passes over the forecast area. A cold front approaching from the west on Sunday will move through the region late Sunday, bringing drier conditions back into the forecast area on Monday. Much of the rain will end from west to east after midnight Sunday, with only isolated rain showers occurring throughout the day Monday followed by dry conditions. Temperatures will continue to be warm through the weekend, with highs in the lower 70s and lows in the mid 50s to lower 60s. Cooler temperatures are forecast for Monday with highs in the mid 50s to lower 60s. /22 MARINE...Main hazard in the near term is areas of dense fog likely over area bays and sounds tonight bringing restrictions to visibility to a mile or less. Dense fog advisories in effect for this potential. High pressure over the Appalachians thru mid week breaks down by Thursday as a cold front approaches and makes passage across the coastal waters. A stronger cold front makes passage late on Sunday. These fronts bring an increased coverage of showers and storms to the coastal waters. A strong southwest to west flow, choppy to rough conditions on bays/sounds and high seas forecast late in the weekend following the passage of the strong weekend front. /10 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...Dense Fog Advisory until 8 AM CST Wednesday for ALZ059-261>266. FL...Dense Fog Advisory until 8 AM CST Wednesday for FLZ201>206. MS...Dense Fog Advisory until 8 AM CST Wednesday for MSZ078-079. GM...Dense Fog Advisory until 8 AM CST Wednesday for GMZ630>635. && $$ This product is also available on the web at:
Area Forecast Discussion
National Weather Service Marquette MI
711 PM EST Tue Jan 17 2017 .SHORT TERM...(This evening through Wednesday) Issued at 325 PM EST TUE JAN 17 2017 12Z raobs/latest wv imagery and RAP analysis show a general zonal flow present over Canada and the nrn tier of the CONUS. There are a pair of shrtwvs over the Great Lks that were responsible for the light wintry mix of pcpn that impacted the se cwa this mrng, but as these disturbances have pressed to the ese, the diminishing dynamic support and arrival of dry air shown on the 12Z INL raob have caused this pcpn to diminish and skies to begin clrg over the nw half. Since h85 temps are above 0C in the zonal flow of Pacific air, sfc temps are running well above normal, mainly well into the 30s. A sfc hi pres rdg axis is present upstream over MN under the large scale subsidence ahead of shrtwv rdg axis trailing the departing disturbances. Some fog did dvlp last ngt under this rdg axis. There is a strong disturbance moving e across nrn Manitoba, and some hi clds on its srn flank extend s into the nrn Plains. Tngt...Large scale subsidence/mid lvl dry air ahead of aprchg shrtwv rdg axis wl bring dry wx tngt and clrg of lingering clds now mainly over the se half of the cwa. With this clrg, expect some fog to dvlp over mainly the se half of the cwa, where winds wl be lighter thru the ngt under incoming sfc rdg axis and the lingering clds wl dspt later in the day and restrict diurnal warming/then allow for more diurnal cooling. Although the disturbance crossing central Canada and the associated sharper forcing wl remain well to the n of Upr MI, the earlier tightening pres gradient/stronger sw winds and arrival of some hi clds over the nw half of the cwa wl restrict the diurnal temp fall and the potential for any fog in that area. Wed...After any lingering fog burns off in the mrng, Wed wl turn mosunny with nothing more than some hi clds lingering to the s of the passing Cndn disturbance. H85 temps are fcst to peak as hi as 7- 8C, so tended toward the hier end of guidance for max temps, especially in areas impacted by the downsloping wsw flow. Expect temps to rise aoa 40 away fm some cooling off Lk MI. .LONG TERM...(Wednesday night through Tuesday) Issued at 325 PM EST TUE JAN 17 2017 Longer range forecast continues to prog an above normal period for temperatures, with a high degree of confidence. Pattern has remained suggestive that high amplitude ridging will reside over the Great Lakes and for the most part the eastern half of the CONUS. There are a few areas of concern for the later portion of the week, with guidance pivoting a embedded shortwave lifting north across the plains towards the Great Lakes late Thur into Fri/Sat. Thermal profiles suggest the bulk of any precip will fall as liquid; however, during the nocturnal periods as the surfaces cool, some of the precip could begin to fall as sleet/freezing-rain Fri ngt/Sat. With the shortwave trapped within the 500mb ridge, it will not be very progressive so expect periodic chances for precip throughout the weekend into early next week. Then beyond Mon ensembles begin to lean towards 500mb ridging re-developing across the Central Plains and eventually lifting northeast towards the Great Lakes region. This will likely displace the main flow of systems further north across the Northern Plains into Ontario/Hudson Bay and clip the U.P. Temperatures throughout the extended, as eluded to earlier, will generally be in the mid/upr 30s, but could easily see several locations touching 40 degrees. Dew points will also be on the rise over the weekend into early next week, which could indicate some potential hydro concerns depending on the duration of above freezing Td`s, which helps to accelerate the loss of snowpack. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 709 PM EST TUE JAN 17 2017 With some low level dry air in place over the nw half of Upr MI, expect vfr conditions to prevail into at least this evng. Not out of the question there could be some mvfr cigs at CMX this evng with a strengthening upslope w wind component and them some lo clds/fog at SAW overngt with a period of lighter winds under passing sfc hi pres, but maintained previous vfr fcst as confidence is low on these outcomes. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 325 PM EST TUE JAN 17 2017 Expect light winds under 15kt into this evening to become wsw up to 25-30kts late tonight into Wed as the pres gradient tightens between a hi pres passing thru the Lower Great Lakes and lo pres crossing central Canada/Hudson Bay. As the low continues eastward and the pres gradient weakens, winds will diminish Wed afternoon/night. For the remainder of the week, expect winds under 20kts as conditions become unseasonably warm over the Upper Lakes with no significant weather features impacting the area. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...KC LONG TERM...Beachler AVIATION...JLB MARINE...KC
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
923 PM CST Tue Jan 17 2017 .UPDATE... Minor changes to temperatures tonight and also some adjustments to rain chances based on current trends and 00Z model data. Increased rain chances across southern into parts of central Oklahoma for this evening and overnight, and across western-northwestern Oklahoma overnight and Wednesday morning. Latest WRF and high res models keep at least scattered showers going well into tomorrow morning even though we anticipate rain activity decreasing in both coverage and intensity as the night progresses. We will keep isolated thunderstorms mentioned across the Red River Valley. && .PREV DISCUSSION... /issued 555 PM CST Tue Jan 17 2017/ AVIATION... 18/00Z TAFs. Shield of light rain and lowering cigs will spread north and east from northern Texas into southern and central Oklahoma through the first 6 to 12 hours of the forecast. MVFR conditions will become widespread after 09-12Z and persist into tomorrow afternoon. PREV DISCUSSION... /issued 307 PM CST Tue Jan 17 2017/ DISCUSSION... Determining rain chances through tonight is the main forecast challenge. Through tonight, increased rain chances across southwestern Oklahoma and western Oklahoma. Latest radars indicated light to moderate rain with even a few thunderstorms moving into western north Texas as of 250 pm ahead of a mid/upper disturbance over western Texas/southeastern New Mexico. This activity will continue to move north and northeast over the next several hours, and will likely weaken a bit as it moves into a drier and more stable airmass north of the Red River. Regardless, chances of getting 0.01" or more tonight across southwestern Oklahoma and western north Texas appear to be very high and went with rain chances 60-100% in these areas. Rain coverage is expected to decrease after midnight as the disturbance lifts northeast. A few rumbles of thunder may occur near and south of the Red River where HRRR forecast MUCAPE values approach 200 J/kg through tonight. No severe storms are expected through tonight due to the very weak forecast instability. Model forecast soundings suggested that all precipitation will be in liquid form, even if it occurs in far northern Oklahoma where surface temperatures may fall into 33-35F range once precipitation arrives mainly after midnight. Rainfall totals are expected to mainly stay below 0.25" tonight. Went towards the warmer side of guidance lows tonight due to abundant cloud cover to limit radiational cooling. On Wednesday, most rain should end by 8 am, allowing for dry weather and near to slightly above average temperatures. If rain is heavy enough tonight to saturate the boundary layer, some fog would be possible mainly during the morning hours across western north Texas and southern Oklahoma. Did not mention fog due to low confidence of occurrence. Clouds may be variable, but overall, think skies will be mostly cloudy. Model guidance highs in the 50s seem reasonable. Thursday and Friday, temperatures will warm up, especially on Friday when many locations may approach or exceed 70 degrees. The warm temperatures combined with breezy west to southwest winds as well as decreasing humidity may elevate fire weather concerns slightly on Friday, though ERC values may be rather low due to abundant ground moisture from recent heavy precipitation. Saturday and Sunday, another storm system may bring additional chances for rain to the area. Latest model forecast temperatures suggested that the precipitation types will remain in liquid form at the ground. Thunder may be possible as well. Above average temperatures are forecast. Next Monday and Tuesday appear to be dry with above average temperatures across the region. MBS && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 39 54 41 61 / 70 10 10 0 Hobart OK 39 53 37 60 / 80 10 0 0 Wichita Falls TX 43 55 40 65 / 90 10 10 0 Gage OK 35 54 35 57 / 50 30 0 0 Ponca City OK 36 53 39 59 / 20 10 10 10 Durant OK 44 54 44 64 / 90 30 10 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ 11/26
Area Forecast Discussion
National Weather Service Blacksburg VA
638 PM EST Tue Jan 17 2017 .SYNOPSIS... A cold front will track into the mountains this evening, then move southeast to the coast by Wednesday morning. Weak high pressure builds over by late Wednesday, then another storm system moves over the southern Appalachians by Friday. && .NEAR TERM /THROUGH WEDNESDAY/... As of 327 PM EST Tuesday... A cold front to our west across central Kentucky and Tennessee this afternoon will east this afternoon and moves southeast through the forecast area tonight into Wednesday. An isolated thunderstorm may be possible over the Mountain Empire and northwest mountains of North Carolina with some instabilities this afternoon into tonight. However, not expecting to much thunder because of cloud cover and rain. The HiResw-arw-east, HRRR, RAP and NAM support placing the highest pops in the west this evening into Tonight. The GFS and ECMWF seem to develop an area of deeper convection east or southeast of our forecast area. The shortwave rotating through Southeast West Virginia supports likely pops in the west, with chance pops to the east. It will remain mild tonight with readings from the upper 30s in the northwest mountains to the mid 50s in the Piedmont. Increased winds speed late tonight into Wednesday morning. From Grayson county Virginia south through portions of the Northwest mountains of North Carolina, winds will approach wind adv levels for a small window around 12z. Because of limited areal coverage and time coverage with lagging CAA will hold off on any wind adv headlines. The northern-stream trough exits Wednesday morning,then a ridge builds in from the west Wednesday afternoon. High pressure will build southeast out of the Ohio Valley. High temperatures Wednesday will vary from around 40 degrees in northwest Greenbrier county to the lower 60s in the Piedmont. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 330 PM EST Tuesday.... As a large cutoff traverses the southern plains, the ridge over the eastern US will amplify and bring quiet weather to the region through Thursday as high pressure settles over the Appalachians and central mid Atlantic. In fact, Thursday looks to offer the first good glimpse of the sun for most of the region in a few days. However, this reprieve will be short lived. By Thursday night the ridge axis will move to our east, leaving behind a lingering wedge of high pressure, and the closed low to our west becomes a progressive open wave. This will allow a surge in isentropic lift and vigorous dynamic support to accompany a frontal passage late Thursday night/early Friday with a good chance of rain. By late Friday the front any dynamic support will be pulling out of the area and bring an end to widespread precipitation. There will be no appreciable change of airmass so temperatures will remain above normal through the end of the week. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 330 PM EST Tuesday.... The main concern for the extended period is the potential for significant precipitation, and to a lesser extent wind, in the Sunday/Monday time frame. Guidance has been consistent with developing a full latitude trof with a deep closed low over the deep south by Sunday night. Persistent southerly flow will allow for efficient moisture transport into the region and by Monday morning, precipitable water values will be approaching 1.2 inches which is near record territory for January. At the surface, occluded low pressure will be moving up the Mississippi valley with a frontal boundary pushing in from the west. With a very moist atmosphere, strong low level flow parallel to thew baroclinic zone, and orographic effects from the Blue Ridge, guidance begins to generate substantial rainfall on Sunday with a continuation through Monday as the front moves through. These parameters are consistent with heavy precipitation events, though we are still out in the day 6/7 time frame and much of this, especially in regards to timing and placement of heavy precipitation, is subject to change with later model runs so the situation will be monitored closely. Some embedded convection is also possible especially as the front moves through Sunday night/Monday morning so this is another aspect to watch in the days ahead. Lingering wrap around precipitation will continue as the large system unwinds and pulls off to the north early next week. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 630 PM EST Tuesday... Widespread MVFR to IFR ceilings were observed this evening across southern West Virginia, southwest Virginia and northern North Carolina. KROA and KDAn were reporting VFR ceilings at 6PM but high confidence that these will lower to MVFR around the 00Z start of the TAF forecast period. A cold front extended from western Pennsylvania to central Tennessee this evening. Models showed good consensus bringing this front across the Appalachians late tonight into early Wednesday morning. This will turn surface winds to the west with wind gusts behind the front at 25 to 35 knots. High confidence of scattered light rain ahead of the front, at least through 1AM/06Z. Areas of fog and drizzle are also expected in the mountains overnight with MVFR to IFR visibilities. Once the front progresses into North Carolina, clouds will become scattered east of the Blue Ridge. Medium to low confidence on how fast clouds will clear out on Wednesday. MVFR clouds will remain in place through much of the day in the favored western upslope areas. Winds will begin to diminish in the mid to late afternoon. Extended Aviation Discussion... VFR conditions will prevail Wednesday night into Thursday. However, this is expected to be short-lived as moisture returns from the southwest. No precipitation type issues are expected through the end of this week...just plain old rain. However, IFR conditions may be possible in rain Thursday night into Sunday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...KK/WP NEAR TERM...KK SHORT TERM...MBS LONG TERM...MBS AVIATION...AMS/KK
Area Forecast Discussion
National Weather Service Shreveport LA
949 PM CST Tue Jan 17 2017 .UPDATE... To adjust some overnight lows, mainly our southern tier of Co/Pa. && .DISCUSSION... Light N/NE winds will keep and really current readings may hold steady or only drop a degree or two with saturation. Few places have more than a 3 to 5 degree spread at this time. No changes to other elements with next big push into NE TX taking shape now. && .PREV DISCUSSION... /issued 508 PM CST Tue Jan 17 2017/ AVIATION... Regional radar mosaics showing scattered to numerous showers across portions of Northern Louisiana...Southern Arkansas as well as Northeast Texas. The rainfall has helped to mix lower ceilings out somewhat with several terminal sites coming in with VFR ceilings near 5-8kft. This will change after dark with ceilings expected to crater to at the very best IFR with LIFR ceilings possible late tonight. Followed the HRRR forecast concerning weather in the 00z TAF package overnight which indicates a beak in the expansive -shra coverage across Northern Louisiana later tonight with coverage expected to increase in coverage and intensity across Northeast Texas in the 18/04-08z timeframe. Some of this activity late tonight through the morning hours on Wed will likely contain lightning associated with it and therefore tried to make reference to when upper level support is strongest...sometime near sunrise and throughout the morning hours on Wed. LIFR/IFR ceilings will likely not mix out during the day Wed and thus prevailed these categories througout the daytime hours across most terminal locations. 13 PREV DISCUSSION... /issued 331 PM CST Tue Jan 17 2017/ DISCUSSION... Persistent broad band of showers across the area, extends back through central TX. Instability quite limited and only a few ltg strikes this aftn so will keep mention of tstms as isold. Bulk of heavy rainfall still upstream, and will materialize as upper low over sw states continue to move east across central/srn plains, with mid lvl temps cooling as airmass continues to undergo deep saturation. Low lvl dynamics will be decent although sfc winds will not be stg as most of the low characteristics not sfc based, including instability, which will remain mostly elevated. Thus, risk for svr wx still marginal despite stg mid and upper lvl flow around base of upper low. Heavy rain may pose a problem at some areas if current trends for training precip, that have been occurring with the lgt to moderate rain thus far with this system, continue as rainfall becomes heavier. Models bringing the dry slot into ne TX fairly early in day Thursday, with precip diminishing areawide by later in aftn. A brief reprieve Thursday night thru Friday, with quick moisture return beginning Fri night under continued deep sw flow. However, this system should move quicker thru area with precip ending durg the day Sunday. /VII/ && .PRELIMINARY POINT TEMPS/POPS... SHV 52 61 57 68 / 70 90 60 30 MLU 54 64 61 70 / 60 70 70 60 DEQ 47 55 50 63 / 70 50 40 20 TXK 50 54 52 65 / 70 70 50 20 ELD 52 57 55 65 / 60 60 60 50 TYR 49 58 53 69 / 100 100 50 20 GGG 50 60 55 67 / 90 100 60 20 LFK 53 67 58 69 / 80 100 60 30 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/13
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday) Issued at 308 PM CST Tue Jan 17 2017 Departing upper shortwave trough over the region has skirted towards the Great Lakes region while an expansive upper low rotates northeast towards the central plains by Wednesday evening. Drier air associated with the sfc ridge is slowly eroding the stratus deck over east central Kansas, likely to stall near the Kansas and Missouri border just before sunset. This should lead to another evening for fog to develop across eastern portions of the area Wednesday, especially in the low lying areas. Do not have high enough confidence for dense fog, but will need to monitor the far eastern areas of the CWA where the HRRR and RAP models are hinting the possibility for visibilities being around a quarter of a mile or less. No other hazards for the short term forecast as the upper low edges closer, sfc trough builds over Colorado, shifting winds to the southwest through the afternoon. High clouds increase on Wednesday while highs are generally in the 40s to lower 50s. The dry air in place across the region confines the precipitation to the southern plains for the time being. .LONG TERM...(Wednesday night through Tuesday) Issued at 308 PM CST Tue Jan 17 2017 Another mid/upper level low pressure will lift out over the plains on Thursday. On Thursday night the lift and moisture will increase in the lower levels, but moisture will be lacking in the mid levels. This means a good chance for drizzle across the entire area into Friday. On Friday a separate shortwave trough from over the west coast will phase and take over the initial wave. Therefore chances for rain will increase mainly north of I-70 Friday and afternoon and overnight. This system will be quickly followed by yet another and even stronger deepening mid level low pressure that tracks over the southern plains this weekend. This will bring a chance for precipitation for the weekend. Although the models disagree on the exact track of the mid/upper level low pressure. This will play a role in where the precipitation will fall. I have already noticed the track has trended south. The other main theme for this forecast is that temperatures will be above normal with highs in the 40s and 50s, while lows stay in the 40s and 30s at least until next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 513 PM CST Tue Jan 17 2017 Low stratus has pushed east of all terminals resulting in VFR conditions through late tonight. Near 05-06Z, patchy fog is expected to develop resulting in MVFR visibilities until 14Z. After this, VFR will prevail with southerly winds. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Prieto LONG TERM...Sanders AVIATION...Heller