The Inside on the Outside

What the forecasters are saying to each other — translated for everyone else.

MORNING EDITION · MONDAY, AUGUST 17, 2026ISSUE No. 2

The Big PictureWPC · 3:59 AM EDT today

Today is the last day of the siege. For most of a week, the same corridor from the Midwest through the central Appalachians has absorbed round after round of heavy rain, and it gets one more today — the most dangerous weather in the country, falling on ground that has nothing left to give. Then it ends: a cold front finally sweeps the whole unsettled mess off the East Coast on Tuesday. Elsewhere the map is rearranging itself. Cool Canadian air spills into the northern tier — Wednesday morning brings the 40s near the Canadian border — while the Southern heat wave not only holds but expands westward, with Extreme Heat Warnings now flying from southern Arizona into the California deserts. And the biggest story of the day isn’t weather at all. It’s climate: El Niño just went from strong to potentially historic.

The Big Story: El Niño Goes HistoricCPC ENSO Diagnostic · Aug 13 · monthly product

A 69 Percent Chance of the Strongest El Niño on Record EL NIÑO ADVISORY

The Climate Prediction Center’s monthly diagnosis lands with a number that deserves attention: better than a 90 percent chance of a very strong El Niño this fall and winter — and a 69 percent chance that the October–December peak exceeds every El Niño on record going back to 1950. Not “among the strongest.” The strongest, period. The Pacific is already running more than 2 degrees Celsius above normal off South America, and the heat isn’t just skin-deep: the subsurface ocean is carrying anomalies as high as 10 degrees Celsius at depth, which is the fuel tank for what comes next. Winds, rainfall, and pressure patterns have all locked into agreement with the ocean — the sign that the atmosphere has fully bought in.

Why it matters to you, in plain terms: this is the pattern that historically stacks the deck for a busy Pacific and a suppressed Atlantic hurricane season — which is precisely what this summer has delivered — and then goes on to shape the winter, typically wetter across the southern tier and milder across the North. Forecasters are careful here, and so are we: a strong El Niño raises the odds of these outcomes. It does not guarantee any of them.

THE NUMBERS · July sea-surface departures: Niño-3.4 +1.4°C · Niño-3 +1.7°C · Niño-1+2 +2.9°C · Subsurface peak anomaly +10.0°C · Historic-event threshold: +2.5°C or higher · Next ENSO update: September 10

Trouble Spots

Flash Flooding — Ohio Valley & Central Appalachians SLIGHT RISK 2/4

One more round, on the worst possible ground. Flash flooding hit this region again last evening, and today’s storms — capable of one to two inches of rain per hour — arrive on soils that forecasters describe as extremely sensitive after a stretch of heavy rain that produced widespread flash flooding and swollen rivers across Appalachia. The most exposed zone runs from southeast Ohio through West Virginia and down the spine into eastern Kentucky, southwest Virginia, and northwest North Carolina. Storms fire by early afternoon and linger through sunset. Then, finally, the front arrives and shuts it off.

HOW SENSITIVE: Forecasters put the odds of exceeding flash-flood thresholds above 70 percent this afternoon across eastern Ohio into West Virginia — mainly along and west of I-79, where 4+ inches has already fallen in the past five to six days.

Severe Storms — Central & Northern Plains SLIGHT RISK 2/5

Today’s main severe threat. A moist axis from northwest Kansas up through central Nebraska into eastern South Dakota will build serious instability by midday, and storms firing ahead of a southeastward-moving cold front should organize into supercells capable of large hail and damaging wind. The threat continues into mid-evening as storms merge into a cluster and push toward the mid Missouri and upper Mississippi Valleys.

Severe Storms — Southern Appalachians SLIGHT RISK 2/5

The same front that ends the flooding delivers a parting shot farther south. Storms develop over the higher terrain this afternoon, then race downhill into the lower elevations by early evening, with damaging wind gusts the main concern — most likely where storms organize into short line segments across eastern Tennessee and western North Carolina.

Dangerous Heat — South, Southeast & Now the Southwest EXTREME HEAT WARNINGS

The Southern heat wave grinds into another week — upper 90s to low 100s, heat indices to 115, and warm nights that deny recovery. What’s new is the westward expansion: the Southwest reheats today and Tuesday into widespread 100s and 110s. Extreme Heat Warnings now cover southern Arizona into the far southeast California deserts, with Extreme Heat Watches up for southern Nevada, northwest Arizona, and southeast California, plus heat advisories in parts of southern California. Limit outdoor exertion, hydrate, find air conditioning, and check on the people most likely to go without it.

The Tropics — Three BasinsNHC/CPHC · 5:00–8:15 AM EDT today

Central Pacific: Lala Exits — and Plans a Comeback

Tropical Storm Lala is 305 miles west of Honolulu and pulling away westward at 13 mph. All coastal watches and warnings for the main Hawaiian islands are down, and the rain is tapering — though 1 to 3 more inches from Maui to Kauai can still trigger localized flooding and mudslides on saturated slopes, and dangerous surf lingers. Here’s the twist: Lala is currently being chewed up by dry air aloft, yet forecasters expect it to regain hurricane strength by Wednesday as it turns northwest toward the remote Northwestern Hawaiian Islands. Weakening today, hurricane again midweek — a reminder that a storm’s obituary is often premature.

LALA, ADVISORY 20 · 60 mph sustained · 997 mb · moving W at 13 mph · forecast peak: 85 mph by Wednesday night · no watches or warnings in effect

East Pacific: Two More in the Queue

The basin keeps producing. Forecasters are watching two areas: a low expected to form several hundred miles south of southern Mexico around midweek, which could become a tropical depression by the weekend as it tracks west-northwest well offshore; and a broader disturbance southeast of Hawaii that may organize late this week and drift into the central Pacific. That second one is worth Hawaii’s attention — it carries a 50 percent development chance, and while most guidance keeps it south of the islands, “south of the islands” is exactly where Lala was.

Atlantic: Four Waves, No Takers

Four tropical waves are marching west across the basin — one near the Cape Verde longitudes, one mid-ocean, one east of the Lesser Antilles, one crossing the western Caribbean — and not one is expected to become anything. The Caribbean wave is throwing the most convection, mostly onto Central America. The basin’s most organized feature this morning is an ordinary cold front out near Bermuda. In mid-August. See The Big Story above for why.

The Insidewhat the discussions actually say

The reasoning behind the forecast, pulled from the technical discussions forecasters write for each other.

The most important number in flood forecasting isn’t rainfall. It’s flash flood guidance — the amount of rain a specific patch of ground can absorb before water starts running. It’s not a constant; it drops as the ground saturates. In Appalachia this morning it is, in the forecasters’ word, “abnormally low” across every time window they check. That’s why today’s forecast of one-to-two-inch-per-hour rates is alarming in West Virginia and unremarkable in, say, Kansas. Same rain, different ground, completely different day.

Two small words that tell you how long this has been going on. In the middle of a technical flood discussion, describing drier air finally arriving behind tonight’s front, the forecaster wrote that conditions will improve “at last.” Discussions are written in clipped, unsentimental shorthand. When that voice editorializes, even two words’ worth, it’s the sound of a desk that has been fighting the same event for a week.

Tuesday’s Plains setup is loaded — and conditional. SPC flags Nebraska, Iowa, Missouri, and Kansas for severe storms Tuesday, but with an unusually candid hedge: the forecast “has become less certain with time,” because storms early in the day could rework the atmosphere and change what happens by evening. If the afternoon heats up as hoped, initial storms bring hail and strong gusts, and an overnight low-level jet could grow them into a damaging-wind complex. Watch it, but hold the certainty — the forecasters are.

Next weekend’s wild card has a name now: a closed low. WPC’s extended discussion notes that both AI and conventional models have converged on a closed upper low developing over the Great Lakes by Sunday — a cut-off spin in the atmosphere that can park and rain for days. The European and Canadian models drift it east slowly; the American GFS is faster and looser. That disagreement is the whole forecast for next weekend in the Northeast and Great Lakes, and it won’t resolve for several days.

The one place a busy Pacific helps. CPC’s outlook discussion connects a dot most coverage will miss: a tropical cyclone forming in the East Pacific by next weekend is expected to fling moisture north into the Desert Southwest, tilting the region wetter. A storm nobody in the U.S. will ever see by name may end up watering Arizona.

Looking AheadCPC · 3:00 PM EDT Sun — current issuance, daily product

August 22–26: a powerful ridge parks over the Great Plains, and the heat follows it. Above-normal temperatures are favored for nearly the entire West and center of the country, with the strongest signal anywhere in the country — better than 80 percent — over the southern Plains, where five-day averages may run more than 10 degrees above normal. The Northeast and eastern Great Lakes are the exception, sitting near normal beneath a trough, with a slight lean wetter. Dry is favored for Oklahoma, Texas, Arkansas, and Louisiana — the ensembles suggest under a quarter inch of rain in five days. Confidence on temperature: 4 out of 5.

August 24–30: same story, wider. The ridge holds, above-normal warmth covers most of the Lower 48 at 50 to 80 percent odds across the Southeast, Mississippi Valley, Plains, Rockies, and Southwest, and the Northeast stays near normal. Confidence drops to 3 out of 5 — high on temperature, murky on rainfall.

Also Watching

• Aurora Watch: The solar material that left the Sun on August 14 arrives today into Tuesday, with a chance of a minor (G1) geomagnetic storm — enough, if it verifies, to bring the northern lights into the northern-tier states tonight and Tuesday night. And there’s a fresh candidate: a flare late Sunday launched another cloud that forecasters are still analyzing to see whether any of it is aimed at Earth. SWPC · 8:30 PM EDT Sun — one cycle behind
• Fire Weather: Elevated conditions today across northeastern California into northern Nevada — humidity down to 15–20 percent over fuels described as critically dry with no recent rain. New fire starts have been noted in southwestern Idaho and eastern Oregon. Tuesday the concern shifts to the Columbia Basin, with locally critical conditions possible in the Cascade gaps where winds gust 20–30 mph, plus a dry, breezy afternoon over the drought-stricken Texas Panhandle and western Oklahoma. SPC Fire Wx · 2:40 AM EDT today
• Drought Monitor: Weekly product; the next national map lands Thursday, August 20 — featured in that morning’s edition.

One Cool Thing

Wednesday morning, look at a national temperature map. Near the Canadian border in the upper Midwest, thermometers will read in the 40s — jacket weather, in the third week of August. That same afternoon, along the Gulf Coast and into the desert Southwest, the heat index will approach 115. That’s a spread of roughly 70 degrees across one country on one day, and it isn’t a fluke: it’s the signature of a cold front doing its job while a heat dome refuses to move. Two seasons, sharing a map, separated by about a thousand miles and one line of low pressure.

Shareables

“There’s now a 69 percent chance this becomes the strongest El Niño ever recorded. Not top five. First.”

“Wednesday morning: 40s near the Canadian border. Wednesday afternoon: heat index 115 in the South. Same country, same day.”

“Tropical Storm Lala is falling apart today and is forecast to be a hurricane again by Wednesday. Storms don’t read their own obituaries.”

For Newsrooms & Reporters

Need a Meteorologist On Air or On the Record Today?

Bob Cox — veteran broadcast meteorologist heard mornings on WTIC NewsTalk 1080 (Hartford) and forensic meteorologist with 30+ years analyzing high-impact weather — tracks these stories in real time and is available for interviews and expert comment: radio, TV, print, podcast, fast turnaround.

Today’s interview-ready angles: El Niño’s 69 percent shot at the record books and what a historic event would mean for winter · why one more inch of rain is a crisis in West Virginia but not in Kansas — the flash flood guidance explainer · Lala’s forecast comeback to hurricane strength · the Southwest’s expanding Extreme Heat Warnings · the 70-degree temperature split across the country Wednesday.

BOOKING: kaitlin@coxweatherservices.com · 888-248-9347 · coxweatherservices.com · attribution: “Bob Cox, meteorologist, Cox Weather Services”

Source Ledgerevery claim, timed & sourced

Our standard: nothing in this briefing older than 8 hours without a flag. Products that update once daily, monthly, or weekly are used at their most recent issuance and marked.

Note: formal NHC/CPHC Tropical Weather Outlooks were not available for this edition; three-basin coverage above is drawn from the corresponding Tropical Weather Discussions, the Lala advisory package, and WPC’s Hawaii discussion, all issued this morning.THE INSIDE ON THE OUTSIDE — written by Bob Cox, Cox Weather Services LLC
Web: coxweatherservices.com · Email: bob@coxweatherservices.com · Published morning & evening

All forecast data from NOAA / National Weather Service national centers (WPC, SPC, NHC, CPHC, CPC, SWPC) — U.S. government products in the public domain. Maps and imagery shown are live auto-updating NOAA graphics and may post-date the text above; the source ledger reflects the text products used at publication. This briefing summarizes and translates official forecasts; for warnings affecting your location, always consult weather.gov, and for tropical cyclone specifics, hurricanes.gov.