jaxjagman

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0239 AM CDT Mon Mar 12 2018 Valid 151200Z - 201200Z ...DISCUSSION... Late-evening model guidance is gradually evolving toward a potentially more active convective pattern by the end of the medium-range period. Eastern US trough that will suppress Gulf air mass should shift east within a few days allowing higher-moisture-content air mass to begin advancing north into TX day4-5. Much of the lower latitudes are expected to moisten significantly into early next week. Threat of deep convection will begin increasing from the Arklatex into the TN Valley during the day5-6 time frame. However, timing of individual short waves will prove extremely difficult as ECMWF/GFS/UKMET/Canadian exhibit different solutions to the break down of the Plains ridge late in the week. While model differences will certainly extend into early next week, Plains ridge should progress into the MS Valley by day8. If this occurs there is some concern organized severe may ultimately materialize across the southern Plains/lower MS Valley. Will not introduce 15% severe probs given the uncertainty but this scenario will be monitored closely.

Signs of a good system towards the end of March

TNI today is the strongest we've seen in awhile -1.3 in 1+2 and -0.3 in region 4,this would be a +1 TNI

Prognostic Discussion for Week 3-4 Temperature and Experimental Precipitation Outlooks NWS Climate Prediction Center College Park MD 300PM EST Fri Mar 09 2018 Week 3-4 Forecast Discussion Valid Sat Mar 24 2018-Fri Apr 06 2018 The Week 3-4 this week is issued against the background of La Nina and an MJO event that continues to propagate eastward with a larger-than-forecast amplitude. Additionally, a high amplitude -AO/NAO event over the past one to two weeks is forecast to be nearer to normal heading into the Week 3-4 period. The recent OLR anomaly maps indicate a large-scale convective structure over the deep tropics that is consistent with La Nina, while the recent evolution of tropical 200-hPa velocity potential anomalies is consistent with the active MJO phase approaching the Maritime Continent, ostensibly resulting in constructive interference with the background ENSO state. Given the observed presence of anomalous tropical forcing mechanisms, statistical guidance that incorporates ENSO and MJO, along with long-term trends, is weighted heavily in both the temperature and precipitation outlooks. The dynamical model guidance varies quite a bit, with a very cold North America predicted by the ECMWF, and the CFS and JMA favoring a warmer solution across much of the central and eastern CONUS. The various models from the SubX suite tend to favor the ECMWF solution, but with large differences among them as well. Most dynamical models favor the continuation of positive height anomalies near and northwest of the Aleutians, with negative height anomalies stretching west-east over the Pacific near 30N. The ECMWF solution, however, reintensifies a -NAO signal over the northwest Atlantic, and its upper-level height pattern over North America appears well-teleconnected to that downstream center of action. The CFS maintains low-amplitude anomalous ridging over the east-central CONUS, more consistent with teleconnections upon the upstream centers of action and MJO forcing. Over Alaska the dynamical blend favors high probabilities of below-normal temperatures; in the official outlook these are tempered by long-term trends (including those related to sea ice extent adjacent to the western and northern Alaska). The temperature outlook consists of a subjective blend of the correlation-weighted, calibrated dynamical model blend and the multiple linear regression tool that inputs ENSO, MJO, and long-term trend time series. These forecast inputs are the most skillful over the past couple of years. These forecasts conflict over parts of the West and Northeast, where areas of EC are depicted. Given the manifestation of ENSO and MJO in important tropical variables (OLR and VP), it is not obvious that the dynamical guidance should be preferred. An objective blend of statistical and dynamical inputs is under development, and until that is ready a prudent course of action is to consider both on nearly equal footing given recent skill evaluations. The aforementioned approach to the temperature outlook is also taken for the precipitation outlook. The various dynamical guidance as well as statistical guidance are in good agreement on above-median rainfall over parts of the Mississippi and Tennessee River Valleys, and to a lesser extent, the northern High Plains. Likewise there is good agreement for increased chances of below-median precipitation over the southwestern CONUS. Over the Northwest and northern California equal chances is depicted due to uncertainty with respect the longitudinal position of the mean trough axis; a slight westward (eastward) shift would favor above-(below-)median precipitation. Below-median precipitation is favored over parts of the Great Lakes, Northeast, and Eastern Seaboard. Dynamical model consensus is the strongest over the Northeast and eastern Great Lakes, while the statistical guidance is more robust over the Southeast coast. Sea surface temperatures are slightly above normal for most of the Hawaiian Islands, although below-normal SSTs are showing up just to the northeast. Anomalous troughing is favored to the west of the islands, supporting anomalous southerly flow. This troughing to the west also supports relatively high probabilities for above-normal precipitation across the entire island chain.

This was the same storm that also produced a F5 in the southern counties of Tn.In Lawrenceburg it went through the Amish country,don't know how no one died from that community. https://en.wikipedia.org/wiki/Tornado_outbreak_of_April_15–16,_1998

The NMME's show a weak to neutral Nina through spring.Then by the time ASO rolls around it's more or less a weak to neutral Nino with a couple models showing a moderate Nino

We'll see.I know i'm harping it,but signs are coming together

Last few days 1+2 has cooled back down.No telling where the MJO is going to be.CFS wants to reform it back into the IO towards the end of the month.

It's still there, but some what better signs but a day later than the earlier map,though it's not really that far off.Trough going through East Asia with a system going through China into the Yellow Sea.This would pump up the heights into China and Mongolia which should if it works out would pump up a +PNA ridge if it were to correlate right.Teleconnection would also support a +PNA ridge mid month,we'll see

March, 2-3 is the Anniversary outbreak of 2012 http://www.spc.noaa.gov/exper/archive/event.php?date=20120302

That's pretty cool.

Hydrologic Outlook Hydrologic Outlook TNZ005>011-023>034-056>066-075-077>080-093>095-020515- Hydrologic Outlook National Weather Service Nashville TN 1106 AM CST Thu Mar 1 2018 ...Spring Flood Outlook... ...Above Average Risk for Flooding This Spring Across Middle Tennessee... Existing Conditions... Middle Tennessee and much of the Mid-South have been dealing with recent heavy rainfall, resulting in an elevated flood threat for the area in the short-term. Recent temperatures have been above normal as well, and many trees and plants are coming out of winter hibernation. The warmer and wetter trend is expected to continue this spring creating an above average risk for future flooding. Streamflows... Current streamflows are well above normal in due to recent rainfall, with many rivers above Flood Stage. Water levels on these rivers, along with the smaller creeks and streams will subside over the next few days but levels on the lower reaches of the Cumberland River and Tennessee River will remain high through the first next week or two of March. Rainfall... Precipitation has been near to above normal for most of the fall and winter, with January being the only significantly dry month across the area. Here are some rainfall totals across Middle Tennessee... Nashville Clarksville Crossville October 3.48 (+0.44) 7.18 (+3.27) 6.23 (+3.19) November 4.46 (+0.15) 2.34 (-2.24) 4.24 (-0.86) December 4.56 (+0.32) 4.38 (-0.65) 4.56 (-0.39) January 1.63 (-2.12) 3.59 (+0.28) 1.68 (-3.08) February 10.91 (+6.97) 9.71 (+5.54) 10.48 (+6.02) Climate Outlooks... The National Weather Service Climate Prediction Center indicates there is a higher probability of above normal temperatures and above normal precipitation across the area for the months of March, April, and May. Summary... Overall, the spring flood threat across Middle Tennessee is well above average in the short-term due to the ongoing flooding and the saturated grounds. An early green-up of vegetation will help diminish the flood threat for the rest of the spring, however, the higher probability above normal precipitation creates an above average risk for flooding through the end of May. $$

For the month of Feb. This was the wettest all-time Feb. for Memphis and Jackson.Nashville finished at #3

STORM SUMMARY NUMBER 02 FOR LOWER MISSISSIPPI AND TENNESSEE VALLEYS HEAVY RAINFALL NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 300 AM CST THU MAR 01 2018 ...HEAVY RAIN STRETCHES FROM TEXAS THROUGH THE CAROLINAS OVER SOME AREAS THAT HAVE SEEN 6 TO 12 INCHES OF RAINFALL OVER THE PAST TEN DAYS... FLOOD AND FLASH FLOOD WARNINGS AND WATCHES AND FLOOD ADVISORIES ARE IN EFFECT FROM NORTHEASTERN TEXAS THROUGH THE LOWER MISSISSIPPI VALLEY...TENNESSEE VALLEY...SOUTHERN OHIO VALLEY...AND INTO THE SOUTHERN APPALACHIANS. FOR A DETAILED GRAPHICAL DEPICTION OF THE LATEST WATCHES...WARNINGS AND ADVISORIES...PLEASE SEE WWW.WEATHER.GOV AT 200 AM CST...A SURFACE LOW OF 1006 MB OR 29.71 INCHES WAS LOCATED IN NORTHEASTERN TEXAS. A QUASI-STATIONARY FRONT STRETCHED EASTWARD FROM THIS LOW ACROSS THE LOWER MISSISSIPPI VALLEY AND INTO NORTHERN PORTIONS OF THE SOUTHEAST...WHILE A COLD FRONT STRETCHED SOUTHWESTWARD THROUGH TEXAS. FARTHER NORTH AND WEST...A COLD FRONT WAS MOVING SOUTHWARD ACROSS THE MIDDLE MISSISSIPPI VALLEY AND SOUTHERN PLAINS. NATIONAL WEATHER SERVICE DOPPLER RADAR AND SURFACE OBSERVATIONS INDICATED THAT HEAVY RAIN AND THUNDERSTORMS WERE OCCURRING FROM EASTERN TEXAS EASTWARD THROUGH THE LOWER MISSISSIPPI VALLEY...TENNESSEE VALLEY...AND INTO SOUTH CAROLINA. MODERATE RAIN SPREAD NORTH OF THE HEAVIER THUNDERSTORMS IN EASTERN OKLAHOMA...KENTUCKY...NORTH CAROLINA...AND SOUTHERN VIRGINIA. ...SELECTED PRELIMINARY STORM TOTAL RAINFALL IN INCHES FROM 800 AM CST TUE FEB 27 THROUGH 200 AM CST THU MAR 01... ...ALABAMA... BRIDGEPORT 4 SSW 3.75 ESTILL FORK 3.65 HUNTSVILLE 3.58 NEW MARKET 3.25 FLORENCE 3.19 MADISON 3.15 SCOTTSBORO MUNI ARPT 3.14 DECATUR - PRYOR FIELD 2.59 NORTHWEST AL RGNL ARPT 2.25 ...ARKANSAS... SHERIDAN 4.96 DE QUEEN 4 NW 4.48 NUNELY 3 SE 4.47 LITTLE DIXIE 1 E 4.32 JESSIEVILLE 6 N 4.29 HOT SPRINGS NATIONAL PARK 3.83 LITTLE ROCK ADAMS FIELD 3.83 TEXARKANA RGNL - WEBB FIELD 3.18 ...GEORGIA... EPWORTH 5 SW 4.04 ELLIJAY 4.00 FLINTSTONE 1 NNE 3.63 TRENTON 3.30 TOCCOA 3.05 FORT OGLETHORPE 2.91 ...LOUISIANA... SHREVEPORT 1.68 CANEY 1.53 BELLEVUE 2 N 1.45 ...MISSISSIPPI... CORINTH 4 W 4.78 HOLLY SPRINGS 4 N 3.94 WINBORN 3.65 FALCON 7 W 3.51 NESBIT 3.23 TISHOMINGO 2.47 ...NORTH CAROLINA... MURPHY 2.78 RANGER 2.71 UNAKA 2.55 BEAVER CREEK 2.43 ...OKLAHOMA... BROKEN BOW 4.19 IDABEL 3.22 VALLIANT 2.89 DURANT 2.00 CLOUDY 1.64 ...SOUTH CAROLINA... ANDREW PICKENS 2.03 SENECA 1.88 CLEMSON-OCONEE COUNTY ARPT 1.86 ...TENNESSEE... WAYNESBORO 5.13 SOUTH PITTSBURG 4.90 BOLIVAR 4.75 BELLS 2 SW 4.66 LEXINGTON 4.09 SAVANNAH/HARDIN CO 3.99 MEMPHIS INTL ARPT 3.69 CHATTANOOGA LOVELL FIELD 3.64 JACKSON MCKELLAR-SIPES RGNL ARPT 3.64 ...TEXAS... ALLEN 5.11 DALLAS FORT WORTH INTL ARPT 4.76 CLARKSVILLE 3.22 HALTOM CITY 1 ENE 3.01 BLUE RIDGE 2.88 PARIS - COX FIELD 2.73 DENTON 2.19 TEXARKANA 10 SW 2.11 THROUGH THURSDAY MORNING...HEAVY RAIN WILL CONTINUE FROM NORTHEASTERN TEXAS THROUGH THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS. ADDITIONAL RAINFALL OF 1 TO 2 INCHES...WITH LOCALLY HIGHER AMOUNTS...IS EXPECTED. AS LARGE PORTIONS OF THESE AREAS HAVE RECEIVED 6 TO 12 INCHES OF RAINFALL OVER THE LAST TEN DAYS OR SO...SOILS ARE SATURATED AND RIVERS ARE IN HIGH FLOOD STAGES ALREADY. THUS...A HIGH RISK OF FLASH FLOODING REMAINS IN EFFECT UNTIL THURSDAY MORNING. THE NORTHERN COLD FRONT WILL PUSH EAST OF THE LOWER MISSISSIPPI VALLEY ON THURSDAY AFTERNOON AND THROUGH THE TENNESSEE VALLEY AND CAROLINAS THURSDAY NIGHT...ENDING THE HEAVY RAIN THREAT. HOWEVER...RIVER FLOODING WILL BE ONGOING. THE NEXT STORM SUMMARY WILL BE ISSUED BY THE WEATHER PREDICTION CENTER AT 900 AM CST. PLEASE REFER TO YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION ON THIS EVENT. TATE

MESOSCALE PRECIPITATION DISCUSSION 0054 NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 1132 PM EST WED FEB 28 2018 AREAS AFFECTED...ARKLATEX, AR, NORTHERN MS, & TN CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY VALID 010431Z - 010901Z SUMMARY...A BAND OF HEAVY RAIN IS EXPECTED TO IMPACT THE REGION INTO THE EARLY MORNING HOURS. LOCAL AMOUNTS OF 3-4" OVER SATURATED SOILS IS EXPECTED TO LEAD TO AND/OR PROLONG FLASH FLOODING. DISCUSSION...A BROAD OVERRUNNING PATTERN HAS SET UP FROM NORTHEAST TX ACROSS AR AND EXTENDING INTO TN WITHIN A REGION OF OVERLAPPING 850 HPA, 750 HPA, AND 650 FRONTOGENESIS PER THE 18Z GFS GUIDANCE. PRECIPITABLE WATER VALUES OF 1.5-1.7" ARE SEEN HERE PER GPS VALUES. THE ATMOSPHERE IS SATURATED AS THE MID- AND UPPER-LEVEL FLOW HAS A FETCH FROM OFFSHORE BAJA CALIFORNIA WHILE THE LOW-LEVEL INFLOW IS OFF OF THE GULF OF MEXICO. THE WIND FLOW IS FAIRLY UNIDIRECTIONAL WITH HEIGHT OUT OF THE WEST-SOUTHWEST ABOVE 2,000 FEET PER THE LITTLE ROCK AR VAD WIND PROFILE. WHILE MUCAPE VALUES OF 500+ J/KG ARE SEEN ACROSS NORTHEAST TX, PLACES FARTHER AFIELD ACROSS AR AND NORTHERN MS HAVE VALUES OF 100-200 J/KG PER SPC MESOANALYSES. WHILE THESE VALUES ARE MEAGER, SOIL CONDITIONS OVER A VAST PORTION OF THE AREA ARE SATURATED DUE TO RAINFALL BEING 300-700% OF NORMAL OVER THE PAST COUPLE WEEKS, WITH THE LARGEST DEPARTURES ACROSS CENTRAL AR, PATCHES OF NORTHEAST TX AND SOUTHEAST OK. EVEN WITH THIS LITTLE INSTABILITY, HOURLY RAIN RATES OF 0.5" ARE POSSIBLE WHICH WOULD COMPROMISE SATURATED SOILS. THREE HOURLY FLASH FLOOD GUIDANCE VALUES ARE PRACTICALLY ZERO ACROSS SOUTH-CENTRAL AR AND ARE LOW FROM THE ARKLATEX ACROSS MUCH OF TN. THE MESOSCALE GUIDANCE ADVERTISES LOCAL AMOUNTS IN THE 3-4" OVER THE MOST SENSITIVE AREA IN AR WITH LOWER, THOUGH STILL THREATENING, AMOUNTS EXTENDING INTO CENTRAL TN. FLASH FLOODING IS CONSIDERED LIKELY.

xcessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1016 AM EST Wed Feb 28 2018 VALID 15Z Wed Feb 28 2018 - 12Z Thu Mar 01 2018 MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 55 WSW OTH 35 W SXT 20 E CEC 35 ENE ACV 10 ENE ACV 35 SSE ACV 45 N UKI 15 ENE UKI STS 50 WSW STS. MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 50 NE LEX 20 ENE JKL 20 SSE MKJ 15 ESE VUJ 30 N CAE AHN 10 SSE GAD 25 N TCL 30 SSW GWO 10 NW OCH 25 WNW LHB BMQ 25 WNW 6R9 30 SW BWD 15 WNW SEP LUD 35 E AQR 35 E FSM 15 NW ARG 15 SSW CIR 15 SE OWB 30 N LOU 50 NE LEX. SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 35 N DEQ 10 W JBR 50 SSE PAH 35 NE MQY 20 N OQT 35 SSE 1A6 AVL GSP GVL 10 SSW 3A1 40 E GWO 40 S ELD 25 ESE PWG 25 SSE 7F9 15 E SEP 10 NNE TKI 35 N LBR 35 N DEQ. MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 30 NE DEQ 20 S M19 35 ENE MKL 25 SW CSV 1A5 25 NNE 47A 20 ESE HSV 25 NNE GWO 10 S 4F4 25 W TYR SLR 30 NE DEQ. ...Upgrade to High Risk for parts of OK/TX/AR/LA/MS/TN... ...Southern Plains through the Southeast States... WPC coordinated with local offices to upgrade a portion of the Moderate Risk area to High Risk. We are concerned at the consistency among recent HRRR runs, in tandem with some of the better performing hi-res models (NSSL WRF, WRF-ARW2) and their 00z runs, all of which point to areal average 3 to 5 inches of rain along the axis that is best supported by GFS and RAP mass fields. The RAP indicates persistent 925-850mb convergence setting up from northeast Texas across southern/central Arkansas into western Tennessee during the late afternoon and evening hours as upstream height falls impinge on the edge of rich Gulf moisture / ahead of an advancing Pacific cold front. Deep west to southwesterly flow affords the opportunity for cell training, very likely leading to embedded amounts greater than 5 inches, especially owing to sizable CAPE and PW values spiking above 1.50 inches in the pre-convective environment / at least 3 standard deviations above the late February climatology. Given antecedent rainfall, 5 to 10 inches in much of this area over the past week, there will be a very high percentage of surface runoff. Forecast models produce peak hourly rain rates approaching 2 inches per hour, which may lead to damaging and life-threatening flash flooding given the saturated pre-conditions on the ground. Very large Slight and Moderate risk areas remain in place extending back westward into north Texas, where the event will initiate this afternoon, and extending farther east, where antecedent conditions are not quite so wet, but where heavy rain rates may exceed flash flood guidance over the southeast states and southern Appalachians through tonight.

Oopps..misunderstood the question until i re-read it just now :(Thought you were talking about back to back to back Nina's with neutral/Nino in between.AFew... gave you the answer

Probably need to watch the Mid month possibly.Trough being shown right now going through E/Asia that could possibly pump up the SER again.Plus the MJO is leaving Africa and headed into the IO. The dashboard also has been showing the last several days this would be the time frame where severe season gets into another gear http://www.spc.noaa.gov/exper/CFS_Dashboard/

Not on the ONI,there never has been

This week's

http://forecast.weather.gov/product.php?site=NWS&issuedby=OHX&product=LSR&format=CI&version=1&glossary=1 http://www.weather.gov/pah/2018_Feb24_EventSummary

ay 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Fri Feb 23 2018 Valid 241200Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX TO THE LOWER OHIO VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH TEXAS TO THE OHIO VALLEY... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TEXAS/LOUISIANA COASTS TO THE MIDWEST... ...SUMMARY... Scattered to numerous thunderstorms will develop across the southern Plains Saturday morning and shift northeastward towards the Ohio Valley through Saturday night. Several of these storms will likely be severe, with damaging winds and a few tornadoes being the primary threat. A few instances of large hail will be possible as well. ...Synopsis... Within a cyclonic-flow regime across the western US, a robust shortwave trough will eject northeast across the central Plains, while acquiring a negative tilt as it approaches the upper Midwest. In response, mid-level heights will fall over much of the Plains and Mississippi Valley through the day. The surface pattern will feature a deepening low lifting north from the Mississippi Valley towards the upper Great Lakes. Trailing to its south, a cold front will accelerate eastward towards the Ohio and Tennessee Valleys, while the preceding warm sector advances northward from the Mid-South to portions of southern Illinois, Indiana, and Ohio. ...Arklatex to the Ohio Valley... As the aforementioned shortwave trough continues northeast towards the upper Midwest, a strong low-level jet is forecast to organize across the Arklatex through the mid-day hours, before strengthening and translating northeast towards the Ohio Valley through the overnight hours. In conjunction with this evolution, the surface warm sector (characterized by dew points in the lower/mid 60s along its northern fringes) will stream northward, reaching areas from southeastern Missouri to southern Indiana through the period. South of the warm front, despite little/modest low-level heating and related buoyancy, favorably moist low levels should support upwards of 1000 J/kg of MLCAPE across parts of the Mid-South by afternoon, with values decreasing to 200-400 J/kg across the Ohio Valley. Countering these lower values of buoyancy, a strong kinematic profile will evolve across much of the region, especially from northern Arkansas to the lower Ohio Valley. Within this region, 925-850mb flow around 60-70 kt will contribute to sizable values of storm-relative helicity through the evening hours. In turn, as a narrow band of convection organizes from the Arklatex to the Ozarks through the day, shear profiles should encourage several bowing/LEWP structures, with embedded supercells possible. Furthermore, forecast soundings and high-res guidance depict a considerable component of low-level shear perpendicular to several bowing segments, enhancing the potential for tornadoes -- a few of which could be strong -- during the afternoon and evening hours. These cells will then race towards the Ohio and Tennessee Valleys during the evening and overnight. Moist adiabatic low-level profiles, while not conducive for high values of buoyancy, may still prove favorable for a few swaths of damaging winds (with an attendant line-embedded tornado threat), as any low-level rotating elements will enhance upward vertical motion and convective intensity. Outside of the main band of convection, although forcing for ascent will not be particularly strong earlier in the day, an isolated discrete supercell or two may form across the Mid-South within warm/moist low-level confluence Saturday afternoon. Favorable storm-relative helicity and effective shear would support a conditional damaging wind and tornado threat during this time frame as well.

Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CST Fri Feb 23 2018 Valid 241200Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE ARKLATEX INTO THE LOWER TO MID MISSISSIPPI VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF NORTHEAST TEXAS INTO THE LOWER TO MID MISSISSIPPI AND TENNESSEE VALLEYS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY NORTH-NORTHEASTWARD INTO THE OHIO VALLEY... ...SUMMARY... Scattered strong to severe thunderstorms are expected to develop and move east-northeastward on Saturday from parts of northeast Texas into the lower to mid Mississippi and Tennessee Valleys. Tornadoes, wind damage and hail will be possible with the more intense storms. ...Arklatex/Lower to Mid Mississippi Valley/Ohio Valley... An upper-level trough will move from the Rockies into the Great Plains on Saturday. Ahead of the system, a moist airmass will be in place at the start of the period from East Texas extending northeastward into southern parts of the mid Mississippi Valley. Elevated thunderstorms should be ongoing in the vicinity of Dallas/Fort Worth around 12Z. This convection is forecast to expand in coverage, moving eastward into the Arklatex where a 40 to 60 kt low-level jet will strengthen. As surface temperatures warm during the day, the convection is forecast to gradually become surface-based. A cluster of storms should become organized as it moves east-northeastward from far northeast Texas across southern and eastern Arkansas during the afternoon. This activity should eventually affect northwest Mississippi, western Tennessee and far western Kentucky by evening. Ahead of the system moving into the Great Plains, a 75 to 90 kt mid-level jet will translate east-northeastward from the southern Plains into the Ozarks. This feature will create strong deep-layer shear profiles favorable for severe storms along the southeastern periphery of the mid-level jet. Strong lift and 0-6 km shear in the 55 to 65 kt range, evident on forecast soundings, will support supercell development. Supercells that interact with the western edge of the low-level jet from far northeast Texas into southern and central Arkansas will have tornado potential. NAM forecast soundings across southern Arkansas at 21Z on Saturday show 0-3 km storm relative helicities near 300 m2/s2 which should be favorable for a few strong tornadoes. Supercells and the stronger multicells embedded in the cluster should also be associated with wind damage and hail. The wind damage threat could increase as the cluster transitions into a line segment, moving eastward from eastern Arkansas into northwest Mississippi, western Tennessee and far western Kentucky by Saturday evening.

2018 February Quick Look Published: February 19, 2018 A monthly summary of the status of El Niño, La Niña, and the Southern Oscillation, or ENSO, based on the NINO3.4 index (120-170W, 5S-5N) Use the navigation menu on the right to navigate to the different forecast sections In mid-February 2018, the tropical Pacific reflected La Niña conditions, with SSTs in the east-central tropical Pacific in the range of weak to moderate La Niña and most key atmospheric variables showing patterns suggestive of La Niña conditions. The official CPC/IRI outlook calls for La Niña continuing through at least early spring, followed by a likely return to neutral conditions around mid-spring. Support for this scenario is provided by the latest forecasts of statistical and dynamical models.