Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/22/18


Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
643 PM EST Wed Feb 21 2018 .AVIATION... Surface anticyclone building across the northern Great Lakes will allow low level flow trajectories to become increasingly more easterly tonight. Lower level dry air advection will help dissipate lower boundary layer/MVFR cloud this evening, also getting additional support with thickening mid cloud aloft. Long period of VFR conditions tonight then right into tomorrow for most of the TAF sites. Will be watching for potential of light precipitation to lift northward across the Ohio border, into Michigan between 10-14Z. HRRR and Regional GEM are the most bullish bringing light precipitation just south of DTW, while the NAM is much farther south. Looking through thermal fields suggests that any forcing that could bring precipitation will be very high in column upwards of 10-12kft agl, as low level dry air feed will hold strong. Preference is to continue a dry forecast with virga likely overspreading the terminal. It appears that for precipitation to occur its going to take a greater northward displacement of the shortwave than the consensus. Also, high confidence that conditional precipitation type will be snow due to wet bulbing effects. To reiterate, a dry forecast will be in the Detroit TAFs. /DTW THRESHOLD PROBABILITIES... * High for ceiling 5000 feet or less right at start of the TAF period. Low tonight. && .PREV DISCUSSION... Issued at 330 PM EST Wed Feb 21 2018 DISCUSSION... Flood watch will be allowed to expire. Slow weakening/flattening of the summer-like upper level ridge (595 DAM at 500 MB) anchored just off the East Coast over the next several days. Frontal boundary and record setting moisture axis has pushed into the southern Ohio Valley, with drier and colder air filtering into southern Lower Michigan this evening, as surface dew pts lower into the 20s and upper teens. Even with mid/high clouds around tonight, temperatures should have no problem falling into the 20s, leading to any residual standing water freezing up. Motorists should be cognizant of the potential icy patches on area roads, not to mention additional potholes. Upper wave coming out of Texas this afternoon will track through lower Michigan tomorrow morning. The question is whether low level dry air and anticylonic flow will hold on to maintain dry conditions, with locations toward the Ohio border possibly getting clipped. 12z Regional Gem remains most adamant, while NAM/GFS hold serve and suppress activity just to the south. Will carry chance pops south of Eight Mile, as latest RAP/HRRR showing a real close call. Thermal profiles suggesting it would be just cold enough for snow, as you have to get up toward 600 MB for ice nuclei present. Yet another upper wave coming out of Texas on Thursday. Stronger and deeper southwest flow with this one will allow deeper moisture to make better inroads north, as PW values around 1 inch reach the southern Michigan border by 12z Friday. The strong high pressure over Eastern Canada will be giving way, but there still an opportunity for surface temps to be at or below freezing as the precipitation initially develops, especially if it occurs before sunrise Friday. Good surge of warm advection then taking over during the day on Friday, with 925/850 mb temps rising into the mid single numbers. Low pressure developing in conjunction with a shortwave ejecting from the Western US trough will bring another chance for widespread precipitation to the region this weekend. Model guidance is in fairly good agreement that this low will track from the Central Plains on Saturday to the UP of Michigan by early Sunday. A rain/snow mix will be possible with the onset of precipitation on Saturday before strengthening southerly flow pulls warm air northward and transitions precipitation to rain. Precipitation then ends early Sunday as a cold front sweeps through the region. Behind the front, better mixing and a tightening pressure gradient courtesy of the strong low pressure system will bring gusty winds Sunday afternoon as highs reach the upper 40s. High pressure builds across the region early next week bringing dry, quiet conditions as upper level ridging re-establishes itself over the Eastern US. Temperatures look to remain above average through Tuesday with highs in the lower to mid 40s and lows in the upper 20s to lower 30s. MARINE... A broad region of high pressure will move across the northern Great Lakes tonight through Thursday. This will maintain dry conditions over all marine areas except possibly some light snow over western Lake Erie. The high will also maintain light wind across the north half of Lake Huron and northeast wind mainly less than 20 knots over southern marine areas. Wind will then veer to the south by Friday as the next low pressure system moves into the western Great Lakes. This system will bring generous coverage of mixed precipitation changing to rain. Mild air will then be swept out by the associated cold front on moderate wind speed shifting to northwest Friday night. High pressure moves in briefly Saturday before a stronger low pressure system arrives during Sunday. HYDROLOGY... Rain has ended across southeast Michigan after a two day stretch that produced 2 to 3 inches over a broad area of the region. The Flood Watch has been cancelled for the potential of areal flooding, however run-off from the rain and melted snow will continue to feed creeks, streams, and rivers. Flood warnings are in effect for most of the primary river basins around southeast Michigan and will likely remain in effect through the end of the week. Additional mixed precipitation and rain during Friday is not expected to contribute to additional flooding or prolong existing flooding. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....CB DISCUSSION...SF/JD MARINE.......BT HYDROLOGY....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
942 PM EST Wed Feb 21 2018 .SYNOPSIS... High pressure off the East Coast will provide warm and moist southerly flow through the week as a cold front stalls and lingers west of the mountains. Rain chances will increase Saturday and Sunday as the front crawls into the forecast area. Near record high maximum and minimum temperatures will continue through the weekend. && .NEAR TERM /THROUGH THURSDAY/... As of 930 PM: After stratocu dissipated late in the day, cloud cover is generally on the increase across the CWFA attm. Guidance continues to suggest mostly cloudy conditions across the area by the wee hours of the morning, though guidance overall is analyzing poorly. The current satellite trends are largely on track, however, and only minor tweaks were needed over the next few hours. Confidence is increasing that any precip overnight will be solely upslope-driven and therefore PoPs have been reduced still more in the Piedmont. Temperatures certainly will be significantly above normal tonight, but especially so if cloud cover fills back in overnight as expected. The temperatures revised with this update are a couple degrees warmer than the previous forecast in portions of the area, and we were already expecting values to threaten record high mins. See Climate section below for specifics. Light winds and the formation of stratus should preclude fog in most areas. That said, GLAMP and HRRR are both developing very low visibility values over the western Upstate (south of the Blue Ridge) late tonight, possibly in association with the cool lakes. On Thursday, any lingering fog in the morning hours will quickly disperse but cloud cover will persist. Latest guidance continues to suggest the aforementioned cold front will become quasi-stationary and remain well west of the FA through the near term forecast period. With not much change in the synoptic pattern, conditions will remain fairly quiet across the FA on Thursday compared to the flooding/severe weather/winter weather threat that will stretch from TX to the OH Valley. Isolated showers on Thursday will once again remain overall confined to the TN border, potentially expanding further eastward but remaining west of the I-77 corridor. Limited instability Thursday afternoon could allow for an isolated thunderstorm or two across the mountains, but confidence is low attm. With the continued warm airmass in place, expect high temperatures to be well above normal once again, nearing record high temperatures for Greenville, Charlotte and Asheville. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/... As of 145 PM EST Wednesday: The persistent upper flow pattern will continue Thursday night through Friday, with dominant high pressure off the southeast coast, and height falls over the Four Corners region of the desert southwest keeping deep layer southwesterly flow in place over the south-central CONUS. At the surface, only the NAM continues to feature a wedge front flirting with our NW NC piedmont on Friday, and it has backed off on the southward extent and depth of any cold air damming layer. Will thus feature no adjustments to temperatures or winds in any ageostrophic, wedge-like fashion for Friday. Max/min temperatures will continue some 15/25 degrees above climo. Mainly isolated showers will continue primarily in the southern mountain upslope areas through Friday. The pattern will start to break down Friday night through Saturday as the southwestern system begins to lift out over the plains. Mid levels will remain fairly dry over the southeast, but sub-850 mb moisture will gradually return on Saturday, with an Atlantic surge from the southeast along with deepening moisture in the strengthening southwesterly flow from the Gulf. Shower chances and southern/western mountain QPF will start to ramp up a bit through Saturday. Instability and triggering appear too weak for much of any thunderstorm mention on Friday and Saturday afternoons. Well above climo temperatures will continue. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... As of 210 pm Wednesday: Although a mean ridge will remain in place across the East through much of the medium range, it will undergo significant deamplification as a series of short wave troughs pass north of the forecast area through the first half of the period. Moist S/SW flow will be underway across the area at the start of the period, as a cold front approaches the southern Appalachians from the TN Valley. Pops gradually increase through Sat night into Sunday, with most locations seeing at least likely pops by Sunday afternoon. The cold front is forecast to clear much of our area by Sunday evening, but may become briefly hung up across the Piedmont, which would support chance pops, especially across southern areas into the daylight hours on Monday. Optimism is increasing that we may see a brief period of dry/mostly sunny and relatively cool conditions Tue into Tue night, as transient contintental high pressure moves across the eastern states. However, guidance suggests another potent short wave trough will eject from the Four Corners region toward mid-week, with Great Plains cyclogenesis resulting in warm frontal/upglide moisture increasing across the Southeast by the end of the day Wednesday. Pops therefore increase once again to 20-40% across our area by 00Z next Thursday. Above-normal temperatures will continue into early next week. However, they will moderate to 5-10 degrees above climo (as opposed to 15-20 degrees) behind the front on Mon-Tue, and may even dip to around normal as cloud cover and perhaps precipitation increase on Wed. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... At KCLT and elsewhere: VFR is expected through the evening, with areas of clear sky. The overall weather pattern will remain essentially unchanged overnight; moist southerly flow is progged to generate a stratus deck late this evening, first at MVFR but eventually lowering to LIFR over most of the Piedmont, though KCLT looks more likely to remain IFR. A light breeze is expected to keep sfc conditions mixed and vsbys largely unrestricted, though fog still should occur near bodies of water and in the valley locations that are more typically foggy. A small shower chance exists near the Blue Ridge. Slow improvement is expected on Thursday with continued weak moisture advection underneath a subsidence inversion. Right now confidence is too low on specific cigs/vsby to mention restrictions at KCLT after 00z Fri, though the pattern will continue to support nocturnal stratus development. Outlook: Unseasonably warm and humid conditions are expected to persist through the end of the week. Shower chances will be highest across the mtns, while periodic CIG and VSBY restrictions will be likely through the week, especially during the late night and morning hours. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 88% High 89% Med 73% High 82% KGSP High 93% Med 78% Med 72% High 96% KAVL Med 77% High 91% Med 72% High 100% KHKY High 83% Low 54% Med 62% High 88% KGMU High 94% High 80% Med 64% High 96% KAND High 94% High 80% Med 73% High 84% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .CLIMATE... RECORDS FOR 02-22 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 72 1897 27 1939 54 1897 2 1963 KCLT 74 1990 33 1963 62 1897 12 1963 1897 KGSP 76 2011 35 1969 55 1980 10 1963 1963 RECORDS FOR 02-23 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 76 1982 29 1989 54 1922 10 1939 KCLT 76 2012 29 1901 56 1944 19 2009 1980 1978 1962 1963 KGSP 76 2012 36 1966 57 1922 15 1963 1996 1939 1980 RECORDS FOR 02-24 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 77 1930 26 1947 50 1985 6 1967 1979 KCLT 80 1982 26 1889 56 1992 16 1967 1930 KGSP 79 1982 33 1901 57 1909 15 1967 1901 RECORDS FOR 02-25 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAVL 78 1930 17 1967 51 1985 -2 1967 KCLT 82 1930 27 1967 58 1890 7 1967 1914 KGSP 79 1930 30 1967 57 1985 8 1967 && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Carroll NEAR TERM...SGL/Wimberley SHORT TERM...HG LONG TERM...JDL AVIATION...Wimberley CLIMATE...GSP
Area Forecast Discussion
National Weather Service Wilmington OH
920 PM EST Wed Feb 21 2018 .SYNOPSIS... Cooler and wet weather has moved into the region as a cold front has stalled southeast of the area. Low pressure tracking just south of the region tonight into Thursday will result in more widespread precipitation. Unsettled conditions will remain into the weekend as additional weather systems pass through the region. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A surface cold front has pushed through the area today and is now draped from Virginia to Tennessee. Late this evening widespread precipitation is pushing northeast across the FA, especially in western locations from Cincinnati to Dayton to Bellefontaine. Further enhancement to the rain is expected for the overnight hours thanks to an upper level disturbance that is forecast to move northeast over the Ohio Valley. The upper level jet streak will also finally start to nudge east with divergence from the RRQ heading east. PWATs also surge at this time to around 1.2" to 1.3" (or near max values for this time of year). As the shortwave moves overhead a weak surface low is forecast to form helping to pull down surface temperatures below freezing across our far northern zones. The HRRR, ARW, NMM, HREF, and RAP all have surface temperatures right around freezing. The GFS and NAM also has a window of below freezing temperatures (mainly between 1 AM and 7 AM). The latest ECMWF has the freezing line slightly farther north. Any precipitation that does fall with surface temperatures below freezing will fall as freezing rain given the warm air aloft. The METRo road model has road temperatures remaining above freezing so thinking is that impacts to area roadways will not be limited. Still though, models are indicating up to a tenth of an inch of ice will be possible across the far north. Given the above have issued a Winter Weather Advisory for freezing rain Thursday morning. The other concern with this round of precipitation will be the potential for flooding. Latest runs of the GEFS, and EPS paints in general a one to two inch corridor across our southwest. Given the strong divergence from the RRQ, extreme PWAT values, and warm cloud depth layers above 9 kft this seems reasonable. Have gone ahead and issued a Flood Watch across the south for this and have kept the watch going until Sunday morning with multiple rounds of precipitation possible. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Thursday morning precipitation will be ongoing across central and southern Ohio with frozen precipitation possible across north/central Ohio. Thursday afternoon the upper level jet streak and disturbance will pull east with weak subsidence in the wake. Thursday afternoon into evening will likely be dry with a brief break in the precipitation due to the mentioned above. Early Friday morning the trough axis across the west coast will remain with the subtropical ridge off the east coast. This setup will allow another round of PV to break off and head towards the Ohio Valley. This means more showers will overspread the area Friday morning. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... An active wet weather pattern to continue into Sunday. Anomalously strong sub tropical ridge over the southeast with a moist southwesterly flow focused into the Ohio Valley to begin the long term forecast period. Multiple waves of rain will lead to a continued flood threat. Moisture will pool ahead of a front moving into the area on Friday with precipitable water values approaching 1.5 inches which is a record value for this time of year. Front to drop southeast across the area Friday and stall out parallel to the mid level flow near the Ohio River Friday night. On the warm side of the system temperatures look to be 15 to 20 degrees above normal with highs on Friday from the lower 50s northwest to the lower 70s southeast. A brief lull in the pcpn activity expected late Friday night. Mid level shortwave and deepening surface low to eject northeast from the central plains Saturday into the Great Lakes Saturday night. Will continue to ramp pops back up to categorical Saturday. Strong low level jet will provide abundant moisture and marginal instability to the area. High shear low cape severe weather setup showing a signal with Sherb parameter Saturday night. Warm temperatures to continue with highs on Saturday from the mid 50s northwest to near 70 southeast. With the front expected to sweep east through the area early Sunday a drying trend to develop. Surface high pressure will build across the Great Lakes offering dry weather from Sunday into the middle of next week. Expect early highs on Sunday with temperatures falling into the 40s and lower 50s in the afternoon. Temperatures to turn cooler but still above normal with highs Monday and Tuesday generally in the 50s. Moisture to return from the south on the backside of retreating high pressure Wednesday. Will hold off any mention of rain until later in the afternoon. Warm temperatures to continue with highs from 50 north to the upper 50s south Wednesday. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... IFR conditions with rain will persist as a slow moving cold front and copious moisture move east of TAF sites. An extended period of moderate rain is expected tonight to Thursday morning as a wave of low pressure ripples along the front from the southwest, providing enhanced convergence and lift. Improvement to MVFR will be possible toward the end of the forecast as drier air works in for a brief period behind the wave of low pressure. Winds from the north will transition to northeast as the front moves farther east. OUTLOOK...MVFR/IFR ceilings and visibilities are likely to continue into Saturday night. MVFR ceilings may linger Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Winter Weather Advisory from 1 AM to 11 AM EST Thursday for OHZ026-034-035-042>046-052. Flood Watch through Sunday morning for OHZ063>065-070>074- 077>082-088. KY...Flood Watch through Sunday morning for KYZ089>100. IN...Flood Watch through Sunday morning for INZ066-073>075-080. && $$ SYNOPSIS...Haines NEAR TERM...Coniglio/Haines SHORT TERM...Haines LONG TERM...AR AVIATION...Coniglio
Area Forecast Discussion
National Weather Service Melbourne FL
900 PM EST Wed Feb 21 2018 .UPDATE... Tonight...Strong high pressure centered near Bermuda with a ridge axis extending to south Georgia is providing a moderate to fresh east/southeast breeze in the low levels. Evening soundings showed precipitable water around 1 inch but the GOES precipitable water product indicates some drier air advecting in from the east. A few spots had sprinkles with one band of scattered to broken clouds that crossed the coast. The GFS picked up on the drying advecting in, so don`t expect anything more than a small chance of sprinkles late tonight along the Treasure Coast, where the breezy east flow will push some more clouds ashore. Won`t add a chance for that low impact event to the forecast though. Our current forecast is going several degrees above MOS mins. This looks good along the coast since winds are unlikely to decouple. We should have some record warm lows especially south of Cape Canaveral. Slightly drier air may allow winds to decouple late across the interior and spoil record warm lows there. The low level flow overnight looks too strong for any significant fog. The HRRR and local WRF don`t indicate any over the north interior, so have tweaked mention of patchy fog to west of I-4. && .AVIATION...Mainly VFR. A brief MVFR ceiling is possible with clouds pushing onshore from the Atlantic. Any late night fog over the north interior is expected to be MVFR and along/west of I-4. && .MARINE... Tonight-Thu...Stout Atlantic high pressure ridge is producing a long fetch of moderate easterly flow. The models show occasional 15-20 knot flow, especially in the southern waters. Also, the increased duration of this onshore flow will allow for a swell component to affect the coastal waters. Buoy 41009 is close to 5 feet, so it`s conceivable that there are 6 foot waves out in the Gulf Stream. Therefore will continue an exercise caution statement there. && .CLIMATE...After several record warm lows yesterday and several likely today, a few more are possible Thu. Here are the record warm minimum temps and the year set: February 21 February 22 February 23 Daytona Beach 68-1989 69-2008 69-2013 Orlando Intl 68-1989 69-1945 69-2013 Sanford 66-2002 68-2008 70-2013 Melbourne 70-1989 69-2003 69-2008 Vero Beach 72-1961 73-1961 73-1961 Ft. Pierce 73-1961 73-1961 71-1979 .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ FORECASTS...Lascody IMPACT WX...Cristaldi
Area Forecast Discussion
National Weather Service Mobile AL
600 PM CST Wed Feb 21 2018 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION... 22/00Z issuance...A persistent and slightly building ridge, surface and aloft, to the east of the region maintains a well established low level southeasterly flow through the next 24 hours. Winds gusty at times, especially during the afternoon hours. Ceilings at MVFR categories this evening and MVFR to VFR on Thursday, but dropping to IFR at times overnight with the potential of patchy fog. Isolated SHRA early this evening, otherwise a rainfree forecast. 12/DS && .PREV DISCUSSION... /issued 405 PM CST Wed Feb 21 2018/ NEAR TERM /Now Through Thursday/...Unseasonably warm and a potentially record breaking temperature pattern continues in the near term along the central Gulf coast. Upper air map analysis shows a highly amplified pattern with a long-wave trof over the western half of the CONUS while a deep layer ridge hangs tough off the Mid-Atlantic and southeast US coast. The upper ridge has been been anomalously strong of late with the western periphery of the H50 ridge over the forecast area today (~5880 meters) being some 50 meters above the climatic daily max for this date. The strength of the ridge and the position of a synoptic scale surface high to our east has resulted in several high temperature records, either tied or broken over the past several days, including today. In fact, worth noting, if the low temperature from last night of 71 degrees holds at Mobile, this would smash the warmest low on record by 4 degrees. This would also be 5 degrees above the normal high temperature for this date. For Pensacola, if the low temperature from last night of 70 degrees holds, this would surpass the previous warmest low on record by 2 degrees. Same as with Mobile, this would also stand at 5 degrees above the normal high temperature for this date. Very little change in the near term forecast philosophy, with a persistence type approach taken with the upper air and surface pressure patterns changing little in position. Will maintain a small chance of showers mainly over the western zones this evening, rooted in a deep, moist southerly flow. High risk of dangerous to potentially deadly rip currents continues along the Florida Gulf coast into tonight due to long period swell (7 to 8 seconds) impinging along area beaches and moderate onshore flow. Indications continue to favor the development of coastal fog tonight which may develop inland thru the night. The high resolution HRRR and higher probabilities of restrictions in visibility at less than 3 miles from the latest short range ensembles are more focused along and southeast of I-65 with the better fog coverage tonight. Overnight lows remain well above normal. For Thursday, there are indications that the western edge of the deep layer ridge may build back west resulting in a continuation of anomalously strong mid level heights and potential of record high temperatures being tied or broken at several locations. /10 SHORT TERM /Thursday night Through Saturday night/...The highly anomalous strong upper level ridge over the western Atlantic will continue to nose westward across the Florida peninsula and into the east central Gulf of Mexico through Friday. A deep layer dry and subsident airmass will remain in place across our forecast area through Friday morning, which supports maintaining a dry forecast Thursday night into Friday morning. Patchy fog formation will also be possible again late Thursday night into early Friday morning. A shortwave impulse in the southwesterly mid level flow pattern northwest of the ridge axis and ahead of the persistent trough over the western CONUS will lift northeastward across Louisiana into Mississippi Friday. Associated increased deep layer moisture and ascent will clip our western zones Friday afternoon into Friday night, favoring a low chance of showers and perhaps a few thunderstorms roughly west of a Butler to Gulf Shores line. Southwest mid level flow will increase across our area Saturday into Saturday night as the broad upper level trough progresses eastward into the central Plains states. The associated cold front will finally get a push eastward into southeast Louisiana and Mississippi and into southwest Alabama by late Saturday night. We expect scattered showers and isolated thunderstorms to develop across much of the area by Saturday afternoon in the warm and moist environment ahead of the approaching front. Deep layer moisture and ascent will increase over our northwestern CWA along the frontal zone Saturday night, and have POPs becoming likely over interior southeast Mississippi and southwest Alabama, with a chance across the remainder of the region. MLCAPE may approach 300-700 J/KG Saturday afternoon, decreasing somewhat by Saturday evening. 35-40 knots of 850 mb flow may also clip our northwestern zones Saturday afternoon and evening, where we may have to monitor for a few strong to marginally severe storms. Otherwise, little change in temperatures is expected through Saturday night, with potential for more record warmth Friday through Saturday. /21 LONG TERM /Sunday Through Wednesday/...The frontal boundary will become oriented near the coast during the day Sunday before pushing offshore Sunday night into Monday. Medium range guidance continues to show deep moisture and ascent spreading over this boundary Sunday into Monday, so have gone with likely POPs through this period. There could be a potential of locally heavy rain Sunday night into Monday morning. Moist westerly flow holds into the middle of next week. Will maintain a chance of POPs during the Monday night through Wednesday period. Slightly cooler temperatures also return behind the front during the extended period. /21 MARINE...Main hazard in the near term would be patchy fog developing near bays and sounds. /10 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...High Rip Current Risk until 3 AM CST Thursday for FLZ202-204-206. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
623 PM CST Wed Feb 21 2018 .SHORT TERM...(This evening through Thursday) Issued at 307 PM CST Wed Feb 21 2018 Surface high pressure shifts east of the area this evening and allows weak warm air advection to ensue ahead of the next approaching shortwave. This scenario will make for increasing clouds overnight, along with temperatures reaching their minimums overnight, then remaining steady or increasing toward daybreak. Hi-resolution models indicate we will most likely stay dry in our forecast area until after daybreak, although the I-90 corridor should see snow shortly thereafter. Snow will then expand north and east across the area during the afternoon hours. By Thursday evening, much of the Minnesota portion of the forecast area should have 1-2 inches of new snow on the ground. This will quite likely hinder the evening commute, especially since snow will be ongoing during it. Have therefore issued a Winter Weather Advisory for most of the MN portion of the area into northwest WI. Southeast of the Twin Cities metro area and across west central WI (including Eau Claire), given the precipitation onset is later and there`s more uncertainty regarding precipitation type, will hold off on an Advisory for now. .LONG TERM...(Thursday night through Wednesday) Issued at 307 PM CST Wed Feb 21 2018 Thursday night snow will be ongoing, with freezing drizzle possible from south central MN into west central WI. By the time the snow ends, the Advisory area can expect 2-4 inches with isolated totals nearing 5 inches in central MN. Nearly the entire area could see some freezing drizzle overnight into Friday morning as we lose saturation in the dendritic layer. Friday is our break between systems as surface high pressure builds in. Given the pattern aloft, however, this break will be short-lived. By Saturday afternoon, the 21.12Z GFS and ECMWF solutions are now in pretty good agreement that a surface low circa 995mb will be located over Iowa, and deepening as it heads toward the Great Lakes. This feature is accompanied by a negatively tilted mid-level trough, and most models yielding 0.25-0.50 inches of QPF. That being said, if this set-up were to come to fruition, it would be a winter storm warning-worthy event for our forecast area. Plenty of time and potential for shifting at this point, but given models are already beginning to hone in on a track, it bears close watching. Sunday through the middle of next week we dry out as ridging dominates for a few days. This will also yield near-normal temps mostly in the 30s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 623 PM CST Wed Feb 21 2018 Quiet weather until Thursday afternoon when snow arrives. NAM/GFS have similar timing on snow pushing into southern MN around 15z. There look to be 2 waves of precip, an initial light band of snow moving through in the afternoon, with the heavier burst and primary accums coming in around 00z and after. The first wave looks to have vis down to 1sm at worst, but wave two will likely produce 1/2sm to 3/4sm vis as it moves through. Also looks like sub vfr cigs will be tied to falling snow. KMSP...Snow may start as early as 18z, but looking at the lack of what the HRRR as at 16z (end of the 22z run), it will probably be closer to 20/21z before snow starts. First bit of snow looks light, but 2nd round will likely have potential for 3/4" to 1" per hour rates. Window for those types of rates looks to be between 1z and 7z Friday. /OUTLOOK FOR KMSP/ Fri...MVFR cigs in mrng. VFR in aftn. Wind W 5-10 kts. Sat...VFR in mrng. MVFR or lower with SN in the afternoon. Significant accums possible Sat night. Wind E 5-10 kts. Sun...MVFR early, VFR late. Wind W 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...Winter Weather Advisory from noon Thursday to 6 AM CST Friday for WIZ014>016-023. MN...Winter Weather Advisory from noon Thursday to 6 AM CST Friday for MNZ041>045-047>053-055-057>063-066-068>070-076-077-084- 085-093. Winter Weather Advisory from noon Thursday to midnight CST Thursday night for MNZ054-056-064-065-067-075. Winter Weather Advisory from 9 AM Thursday to midnight CST Thursday night for MNZ073-074-082-083-091-092. && $$ SHORT TERM...LS LONG TERM...LS AVIATION...MPG
Area Forecast Discussion
National Weather Service Norman OK
517 PM CST Wed Feb 21 2018 .AVIATION... 0Z TAFs - Ceilings will decrease this evening and continue into Thursday. Freezing rain and sleet will be possible parts of the area this evening but areas of FZDZ is expected to be the primary precip overnight into the morning. Another round of freezing rain/rain is expected Thursday. Winds will gradually begin to shift towards the south Thursday. && .PREV DISCUSSION... /issued 343 PM CST Wed Feb 21 2018/ DISCUSSION... Persistent southwest flow aloft will keep the southern Plains within an unsettled weather pattern through Saturday with periods of precipitation expected. For this afternoon/evening, a wintry mix of sleet and freezing rain will continue to shift east-northeastward. As this precipitation moves out this evening, forecast soundings suggest areas of freezing drizzle will be possible into the overnight hours. NAM soundings suggest a saturated layer from the surface to ~800 mb. NAM isentropic chart at ~295K indicates low-level ascent as well. There is even a signal in the HRRR and HRRRX of some light echoes. The 4 KM NAM is even more aggressive than the HRRR/HRRRX. So in addition to freezing drizzle, light freezing rain could also be possible. Based on the aforementioned analysis, freezing drizzle was added to the forecast for tonight. With the potential for freezing drizzle, opted to expand the Winter Weather Advisory through 9 AM. Freezing drizzle is more efficient at accretion, so travel impacts would occur in areas that experience it. Another round of precipitation is expected mid-Thursday morning into Thursday afternoon. All model guidance suggests temperatures will warm above freezing tomorrow; however, confidence is not high as guidance has been too warm with this air mass. In addition, surface winds are expected to remain northerly through mid-morning (which isn`t favorable for temperatures to warm above freezing). Forecast NAM soundings have temperatures right around 33-34F in central Oklahoma during onset of precipitation. Opted to trend toward the NAM solution (with temperatures warming only slightly above freezing in the afternoon) and also added a mention of freezing rain (along with rain) into the afternoon hours. Confidence is not enough to extend a Winter Weather Advisory beyond 9 AM--but the trend will to be monitored carefully. Yet another round of precipitation is expected Friday afternoon into Saturday. Confidence is higher that temperatures will be above freezing with this round of precipitation. Elevated instability begins to increase as well, so thunderstorms will be possible. Warmer, above average temperatures are expected by Saturday afternoon. Many locations may have high temperatures in the 60Fs. By late Saturday, a cold front is expected to pass by the area. This should bring an end to the unsettled pattern. The air mass behind this front appears to be from downslope flow, so it does not appear to be that cold. As a matter of fact, no significant temperature change is expected for Sunday. Quiet, seasonable weather is expected in the front`s wake on Sunday and Monday. More unsettled weather may return by Tuesday and Wednesday of next week as southwest flow returns with a longwave trough across western United States. Isentropic ascent ahead of the wave will increase the chance of precipitation. At this time, temperatures appear to be too warm for winter precipitation. Mahale && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 23 34 32 52 / 40 60 0 40 Hobart OK 23 35 30 51 / 30 40 0 30 Wichita Falls TX 27 35 33 49 / 30 60 0 60 Gage OK 21 35 30 54 / 30 30 0 0 Ponca City OK 27 35 31 51 / 50 50 0 20 Durant OK 32 39 39 53 / 60 80 40 80 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Winter Weather Advisory until 9 AM CST Thursday for OKZ004>048- 050>052. TX...Winter Weather Advisory until 9 AM CST Thursday for TXZ083>090. && $$ 30/25/01
Area Forecast Discussion
National Weather Service Portland OR
801 PM PST Wed Feb 21 2018 .SYNOPSIS...Cool weather stays over the region into next week with northerly flow aloft. A shortwave trough will likely provide more accumulating low-elevation snow late tonight into early Thu. Additional troughs will continue a threat for rain and low-elevation snow this weekend into early next week. && .SHORT TERM...Tonight through Saturday...As alluded to in the previous discussion, we made a few changes to the Winter Weather Advisory, namely to add the South Willamette Valley and our northern coastal zones to the advisory. Precip briefly fell as rain at KAST before changing over to snow, though temperatures remain slightly above freezing at the airport. Current KLGX radar and 00z runs of the 3 km NAM and HRRR suggest a couple of healthy snow bands will make their way down the coast...likely enough for an inch or two of accumulation above the immediate beaches. Best chance for significant accumulation along the coast will be on the capes and in the hills, a few hundred feet above sea level. However, some minor slushy accumulations of less than an inch are possible down to sea level, and coastal valley/slightly inland locations such as Tillamook and Knappa also stand a better chance to receive an inch or two than the immediate beaches. Models and radar trends suggest the main batch of precipitation will travel south along the coast with tonight`s low, with perhaps a couple snow showers in the instability behind it...but not enough to warrant continuing the advisory beyond midnight tonight. Latest model runs have also trended a bit higher with QPF throughout the Willamette Valley, with up to 0.25 to 0.50 inch total in the central and southern valley. Even with a bit of melting at the onset and low snow-water ratios, it appears there will be a swath of 2 to 4 inch totals somewhere in the Willamette Valley. Therefore we expanded the Winter Weather Advisory southward into the Eugene metro; accumulating snow for the Eugene area should start around midnight tonight, peaking between 1 to 4 AM, then taper off shortly before the morning commute. The remainder of the Winter Weather Advisory looks to be in good shape, as latest radar imagery shows light snow already developing down the I-5 corridor from Chehalis down to the PDX metro. Temps are still generally too warm for accumulation, but this will change as isentropic lift enhances precip rates and cools the column over the area. 00z NAM cross-sections through the Willamette Valley show a period of excellent lift through the dendritic growth zone, spreading quickly south through the Willamette Valley between 06z and 10z. This could lead to local 1 inch/hr snowfall rates, which is also shown in the NAM and new 00z GFS QPF fields. Considering how quickly precip changed from rain to snow at Astoria in southerly flow, see no reason now to disbelieve the NAM Bufr soundings that show the precip type mainly as snow throughout the Willamette Valley and for all but the Central Coast of Oregon. It is important to note that there are two low centers associated with this system, and one is still hanging back over the Seattle metro area. Some models, such as the 3km NAM, suggest this portion of the low will continue to hang back behind the low presently heading down the coast, possibly causing some light snow to persist into the morning hours around the PDX metro. Regardless, the impacts from snow and ice overnight will likely be felt during the morning commute, but this could be an additional complicating factor. At this point, we are only going with very minor accumulations from this possible secondary push of snow Thursday morning, but it will need to be watched closely. Eventually skies are expected to clear Thursday, allowing for some melting of the snow. However, temps will likely top out in only the mid 30s for most of the lowlands due to the snow cover and even colder temps aloft. Clear skies persist into Thu night. This, combined with the likelihood of snow still on the ground for some locations, will probably lead to low dropping into the low to mid 20s for much of the lowlands. The gorge and Upper Hood River Valley may even see lows in the teens. Friday Still not out of the woods Friday for low elevation snow. GFS and NAM indicate yet another short-wave in northwest to north flow aloft sliding south along the Southern British Columbia Coast and early Fri morning. Leading precip edge expected to reach the S Washington and far N Oregon coast by 18Z Fri. Precip then sags south into Clark County and far North Willamette Valley between 18Z and 21Z. Model 850 mb temps valid 18Z Fri forecast to be -7 to -9C. This is typically cold enough for snow to the valley floor. However, a couple of negatives include little to no offshore flow through the Gorge and strengthening south-to-north gradient through the Willamette Valley. Initial precip in SW Washington and far North Willamette Valley will likely be a rain/snow mix, or all snow in areas above 500 ft. BUFKIT sounding for KPDX valid 18Z shows a surface temp of around -5C. Believe that is too cold. Low-level air mass slowly moderates through Fri afternoon, with the GFS indicating 850 mb temps -3 to -6C, with the coldest temps in the Gorge and Cascades. South low-level flow in the interior valleys increases Fri afternoon as well. The cool pattern continues Fri night and Sat. Models show another short-wave impacting the area beginning late Fri night. Model 850 mb temps expected to be -4 to -6C and there appears to be enough over- water trajectory and south low-level flow to keep snow levels above the valley floors. Still looking at snow levels around 1000 to 1500 ft across much of the area Sat morning. Weagle/Pyle/Weishaar .LONG TERM...Friday night through Tuesday...No changes. Previous discussion follows. Stuck in a colder north to northwesterly flow pattern that will continue to maintain pretty low snow levels through the period. The models show the system starting to drop down from the north on Friday will move through Friday night, followed by trailing short waves through Saturday into Saturday night. This series of short waves, while quite cool, has a decent onshore flow with them with an increasing southerly gradient across our forecast area. The net result would be that this should begin to lift snow levels a bit off the valley floors, probably closer to 1000 feet or so by later Friday night or Saturday morning. The Cascades, foothills and coastal mountains could see pretty decent snow accumulations through this time frame. The next system drops in late Sunday and Sunday night, continuing Monday. The ECMWF has a surface low that would induce offshore flow and probably drop snow levels back down near the valley floors, the other models less certain of that. Nevertheless, the snow levels will continue to be quite low. Precipitation is likely to ease by Tuesday but with snow levels continuing quite low. pt && .AVIATION...There is still some residual stratocumulus clouds in the south Willamette Valley with associated MVFR cigs, otherwise conditions are mostly VFR across the area this afternoon. The next low pressure system dropping south along the coast tonight will bring a mixture of MVFR and IFR conditions to the area from south to north tonight. It will be cold enough for some snow in the inland areas with snow levels dropping to the valley floors again, with those areas more at risk of IFR conditions. South of KSLE there will be southerly winds due to the path of the associated surface low moving in that will persist near KEUG until the end of the event around sunrise Thursday so that snow chances are less at KEUG than farther north. Precipitation will drop off pretty quickly from north to south Thursday morning with a turn toward VFR conditions Thursday afternoon. PDX AND APPROACHES...VFR conditions this afternoon and early evening. A few flurries possible after 02Z. IFR conditions with increasing snow likely by midnight, with the heaviest snow through 12Z or so. Precipitation then decreasing to flurries, drying out rather quickly in the morning. VFR conditions developing mid to late morning continuing through Thursday afternoon. pt && .MARINE...The next surface low along the B.C. coast will move over the Washington coastal waters this evening and into the Oregon waters after midnight, then onshore around Newport by sunrise Thursday. This low is looking strong enough to produce NW gales on the back side of the low over the outer waters, with seas building to 10-12 ft. Inner water winds look below Small Craft Advisory levels for now but could get gusts up close to 20 kt in the prefrontal southerlies. Another low pressure center will drop SE out of the Gulf of Alaska over the weekend. This should have a longer fetch of NW winds on the back side of the low that will likely drive seas well into the teens, but models have wavered quite a bit on how high seas will peak and exactly when. At least mid teens seem reasonable for now. Look for Small Craft Advisory threshold NW winds with this system across our waters as well. pt && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory until 6 AM PST Thursday for Greater Portland Metro Area-Lower Columbia-Western Columbia River Gorge. Winter Weather Advisory until 6 AM PST Thursday for Coast Range of Northwest Oregon-Northern Oregon Cascade Foothills. Winter Weather Advisory from 11 PM this evening to 8 AM PST Thursday for Cascade Foothills in Lane County-Central Coast Range of Western Oregon-Central Willamette Valley- South Willamette Valley. Winter Weather Advisory until midnight PST tonight for North Oregon Coast. WA...Winter Weather Advisory until 6 AM PST Thursday for Greater Vancouver Area-I-5 Corridor in Cowlitz County-Western Columbia River Gorge. Winter Weather Advisory until midnight PST tonight for South Washington Coast. PZ...Gale Warning until 2 AM PST Thursday for Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 NM. Gale Warning until 7 AM PST Thursday for Waters from Cascade Head to Florence OR from 10 to 60 NM. && $$ Interact with us via social media: www.facebook.com/NWSPortland www.twitter.com/NWSPortland This discussion is for Northwest Oregon and Southwest Washington from the Cascade crest to 60 nautical miles offshore. This area is commonly referred to as the CWA or forecast area.
Area Forecast Discussion
National Weather Service Pueblo CO
403 PM MST Wed Feb 21 2018 .SHORT TERM...(This evening through Thursday) Issued at 358 PM MST Wed Feb 21 2018 An upper level trof will move into UT and AZ tonight, and ahead of this system snow will increase along the Continental Divide. Several inches of snow will fall over the San Juan mtns where favorable orographics are expected. There currently is a Winter Wx Advisory in effect for this area, and will leave that as is. Some snow will also spread into the eastern mtns tonight, but accumulations are expected to be light. Areas of the San Luis Valley will probably see some light snow as well along with areas of fog. This afternoon warm overrunning over the far southeast areas has kept a lot of cloud cover over that area, along with some light flurries, and it looks like this will continue. The HRRR and NAM show the potential for low stratus developing later tonight along the I-25 corridor, mainly from around Walsenburg and northward, and then these clouds hang around thru at least midmorning Thu,. Theses areas could see some light snow tonight thru Thu morning. On Thu, the disturbance moves northeastward over the state. It looks like by afternoon, snow will still be found over some of the mtn areas, but it should be lighter than during the morning hours, with only light additional accumulations possible. Also, by afternoon it looks like low clouds over portions of the plains should dissipate and dry conditions are expected in the afternoon. Temps on Thu will still be below average, with mostly in the 30s over El Paso county and in the 40s over the rest of the plains, and the high valleys should see mainly 30s for highs. .LONG TERM...(Thursday night through Wednesday) Issued at 358 PM MST Wed Feb 21 2018 The weather pattern remains active through much of the long-term forecast period. As the previously mentioned upper disturbance lifts north and east out of Colorado Thursday evening, snow will become light and scattered/isolated across the continental divide into Friday morning. By Friday afternoon, the next upper-level trough digging into the four corners region will cause an uptick in snow coverage and intensity across the continental divide through late Friday night. Expect another 3-5 inches with locally higher amounts. Strong southwest flow over the state and deep mixing will allow for gusty surface winds and low RH values, leading to heightened fire danger across the plains Friday afternoon. However, RH values are not expected to reach Red Flag criteria. High temperatures on Friday will range from the mid 40s to mid 50s across the plains. As the upper trough advances east across the state late Friday, surface low pressure will deepen in western Kansas, sending a cold front down the eastern Colorado plains early Saturday. Gusty north/northwest winds are forecast along and behind the cold front, lasting most of Saturday. Expect only isolated snow showers in the northern portions of the southeast Colorado plains late Friday into early Saturday. Precip chances will become isolated across the mountains Saturday. High temps on Saturday will only be slightly cooler, reaching the mid 40s across the plains. The next upper disturbance will move across the state quickly on Sunday, bringing brief snow chances to the continental divide during the first half of the day. The plains will remain dry with highs again in the mid 40s. Dry weather will dominate southern Colorado Monday and Tuesday under relatively undisturbed westerly/southwesterly flow. However, gusty winds and low RH values will bring the potential for heightened fire danger both days. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 358 PM MST Wed Feb 21 2018 Low stratus is expected to increase at KCOS this evening, with conditions becoming MVFR or IFR, along with the potential for some light snow thru much of Thu morning. Conditions are expected to become VFR for Thu afternoon. VFR conditions are expected at KPUB thru this evening at KPUB, but clouds will increase tonight and there is the potential for low stratus to develop with MVFR and maybe brief IFR conditions into Thu morning. VFR conditions are expected by late Thu morning. VFR conditions are expected at KALS until early Thu morning, when some snow showers and lower clouds are expected to be in the area. MVFR or even IFR conditions will then be possible at KALS in the morning hours, especially if snow does develop. By late morning conditions are expected to improve. KALS has had some gusty winds this afternoon which should decrease early this evening. Thu afternoon KALS is expected to see gusty southwest winds develop again. && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 8 PM this evening to 5 PM MST Thursday for COZ068. && $$ SHORT TERM...28 LONG TERM...LINE AVIATION...28
Area Forecast Discussion
National Weather Service Shreveport LA
837 PM CST Wed Feb 21 2018 .UPDATE... Have made no changes to the current Flash Flood Watch which remains in effect through 6 am Thursday Morning. Cold front which has pulled up stationary late this evening was oriented from just north of BPT to just north of ESF attm. Best upper level forcing and overrunning frontal ascent will take place across our southeast zones for the remainder of the night so for this reason, have increased pops to high end categorical variety. Good agreement from the HRRR and the latest 00z NAM output for a decreasing trend in precip coverage and intensity across our northwest zones. Pops were scaled back to low end chance variety across our northwest after midnight so have left that pop grid unchanged. Temperatures remain tricky overnight as hourly temperatures have wavered back and forth in the colder airmass across NE TX and portions of NW LA and SW AR over the past hour. The stationary front to our south will not begin returning back northward until the daytime hours on Thu so plan on keeping temperatures nearly stationary for the remainder of the night and the currently fcst hourly grid output reflects this trend well. No other changes are necessary attm...13. && .PREV DISCUSSION... /issued 555 PM CST Wed Feb 21 2018/ AVIATION... For the 22/00z TAFs, IFR/LIFR flight conditions are expected to persist at most terminals for the entire TAF period. Widespread convection will also continue without much of a break for the next 24 hours. The rain may be heavy at times. In fact, the initial conditions are expected to change very little for the duration of the period. The exceptions might be some portions of Southeast Oklahoma, extreme Southwest Arkansas, and Northeast Texas, including KTXK and KTYR. The convection may taper off a bit during the early morning hours, but is still expected to prevail for much of the daytime hours of Thursday. CN && .PRELIMINARY POINT TEMPS/POPS... SHV 52 65 60 74 / 100 70 80 50 MLU 52 75 64 79 / 100 70 50 30 DEQ 43 53 50 63 / 100 80 90 90 TXK 45 55 54 66 / 100 70 90 90 ELD 45 63 60 73 / 100 70 70 60 TYR 44 56 52 69 / 90 70 90 70 GGG 46 60 55 72 / 100 70 80 70 LFK 55 70 60 79 / 100 60 60 40 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Flash Flood Watch until 6 AM CST Thursday for ARZ050-051-059>061- 070>073. LA...Flash Flood Watch until 6 AM CST Thursday for LAZ001>006-010>014- 017>022. OK...Flash Flood Watch until 6 AM CST Thursday for OKZ077. TX...Flash Flood Watch until 6 AM CST Thursday for TXZ096-097-108>112- 124>126-136>138-149>153-165>167. && $$ CN/13