The Inside on the Outside
The Big Picture
Two hazards are on the move today, and they’re headed the same direction: east. A corridor of heavy rain and flash flooding — currently soaking the central Plains, mid-Mississippi and Ohio Valleys, plus southern Arizona — slides toward the Mid-Atlantic coast by Thursday, where forecasters have already flagged an excessive rainfall risk from I-95 to the coast. Severe thunderstorms ride along for the first leg, capable of hail and a couple of tornadoes across the mid-Mississippi Valley tonight. Meanwhile the South’s heat wave shows no signs of breaking — record highs and record-warm overnight lows are in play again today — even as it starts to make room for the Southwest to inherit its own bout of triple digits later this week. And 2,500 miles west, a major hurricane is bearing down on a national monument with hurricane warnings posted.
Lead Story: Hurricane Lala & the Northwestern Hawaiian Islands
Major Hurricane Bearing Down on Papahānaumokuākea HURRICANE WARNING
Lala is a Category 3 hurricane — 125 mph winds, minimum pressure 953 mb — churning northwest at 9 mph roughly 300 miles south of Maro Reef. Forecasters have it turning north early Thursday, putting the core near the northwestern Hawaiian Islands by Thursday. A Hurricane Warning covers the Papahānaumokuākea Marine National Monument from Lisianski Island to Maro Reef; a Tropical Storm Warning extends the coverage east to French Frigate Shoals. Hurricane conditions are expected in the warning area by Thursday, with tropical storm conditions arriving as soon as tonight. Large, damaging surf is already building and is expected to inundate some of the monument’s low-lying atolls. Some gradual weakening is expected over the next few days — but forecasters say Lala should remain a hurricane right through the weekend.
Trouble Spots
Flash Flooding — Central Plains, Mid-Mississippi & Ohio Valleys SLIGHT RISK 2/4
Two separate flash-flood setups are running today. Along a cold front dropping through the Ohio Valley, an overnight complex of storms is expected to redevelop this evening into a corridor of training thunderstorms from southeastern Missouri through southern Illinois into western Kentucky and Tennessee — forecasters see a real shot at 1–2 inches per hour for several hours, with local totals of 2–4 inches and isolated amounts to 6 inches. A second, separate area of concern sits upstream across eastern Nebraska into northern Missouri, where the same front is squeezing out its own round of heavy downpours this afternoon. Southern Arizona’s monsoon adds a third, smaller flash-flood threat around Tucson today, with rainfall rates aggressive enough to overwhelm the desert’s naturally low flood-guidance thresholds.
Excessive Rainfall — Mid-Atlantic, Thursday SLIGHT RISK 2/4
Tomorrow’s the one to watch closer to home. The same front pushes into the Mid-Atlantic Thursday afternoon, and forecasters expect a line of storms to fire almost on top of the Philadelphia–Baltimore–DC corridor before drifting east. The heaviest rain currently looks likely to set up over New Jersey, Delaware, and the Virginia Tidewater — with the New York City metro sitting right on the edge of the higher-risk zone. Exact placement is still moving; see The Inside for why.
Severe Storms — Ozarks, Mid-Mississippi Valley & Southern Arizona SLIGHT RISK
Storms redeveloping this evening in the same corridor as the flooding threat carry large hail and damaging gusts as their primary hazards, with a strengthening low-level jet supporting an isolated tornado or two as activity clusters and pushes east overnight. Separately, near the Nebraska/South Dakota state line, a supercell risk exists this afternoon with large hail the main concern before storms transition to a wind-driven cluster.
Dangerous, Record Heat — South, Southeast & Southern Plains EXTREME HEAT WARNINGS
Record highs and record-warm overnight lows — some overnight temperatures stuck in the low 80s — are expected again today across the Desert Southwest and the southern Plains into the Deep South. Combined with oppressive dew points, that means essentially no overnight recovery from scorching daytime highs. Extreme Heat Warnings remain posted across the Desert Southwest and southern Plains into the Deep South; Heat Advisories cover all of Florida and the Southeast coast. Limit outdoor activity, stay hydrated, and check on neighbors and family without reliable air conditioning.
The Tropics — Three Basins
Pacific: An Assembly Line, With Lala Leading It
Lala leads (see above). Behind her, forecasters are watching two more candidates. A tropical wave well east-southeast of Hawaii is given high odds of becoming a tropical depression in the next couple of days — 70 percent within 48 hours, 80 percent within a week — as it tracks west-northwest into the central Pacific. Separately, an area of low pressure is expected to form several hundred miles south-southwest of Mexico around the end of the week, with high odds (80 percent) of slow development into a depression by this weekend as it stays well offshore.
Atlantic: As Quiet as the Bulletin Allows
This morning’s outlook is a single sentence: tropical cyclone formation is not expected during the next seven days. Two weeks into the climb toward the September 10 statistical peak, that’s close to the quietest statement the National Hurricane Center can physically issue — and a striking contrast to the traffic building on the other side of the country.
The Inside what the discussions actually say
The reasoning behind the forecast, pulled from the technical discussions forecasters write for each other.
A “tall, skinny” atmosphere is a heavy-rain atmosphere. Forecasters describe Thursday’s Mid-Atlantic setup as having a “textbook signal for heavy rainfall,” built on soundings showing moisture stacked from the surface all the way to the tropopause — what they call a tall, skinny CAPE signature. Translation: when the whole column of air is loaded with moisture rather than just a shallow layer near the ground, any thunderstorm that fires can wring out rain at a much higher rate, because there’s more fuel available at every level for the storm to tap.
The NYC-metro hedge, spelled out. Forecasters put it almost apologetically: the heaviest-rain signal for Thursday’s Mid-Atlantic event is “pretty close to the NYC metro, but the heaviest may lie just south,” and they explicitly say it “will bear watching the trends over the next 24 hours” before deciding whether New York City and western Long Island need to be upgraded into the higher-risk zone. That’s a real, live uncertainty — not hedge-language for its own sake — and it’s worth a second look at tomorrow’s issue before Thursday.
Forecasters grading their own models, in writing. The Climate Prediction Center’s long-range outlook is built by blending three ensemble models — but not equally. Their discussion states plainly they’re weighting the European model’s ensemble mean higher than the American and Canadian models “due to recent model skill.” That’s forecasters keeping score on which model has been performing best lately and adjusting their blend accordingly — the kind of judgment call a weather app can’t make for you.
A hurricane warning for a place with no year-round residents. The Papahānaumokuākea Marine National Monument — the target of Lala’s hurricane warning — is a protected reef and atoll system with no permanent population. The warning still goes up exactly the way it would for a populated coastline, because the monument hosts researchers, seabird colonies, and monk seal habitat that a Category 3 storm can genuinely threaten. The National Hurricane Center doesn’t check a census before issuing a warning.
Looking Ahead
For August 24–28: a strong, amplified ridge parks over the Four Corners into the Plains, driving above-normal temperatures across most of the country — better than 80 percent odds over the southern Plains. The Northeast and Ohio Valley sit under a weak trough and trend near-to-below normal on temperature, with a slight lean toward wetter-than-normal for the Carolinas, Mid-Atlantic, and Northeast coast, Connecticut included. By August 26–September 1 the same pattern largely holds, just weaker — the ridge persists out west, the eastern trough softens, and the wetter-leaning signal along the Northeast coast continues. Confidence: average, 3 out of 5 in both periods — solid agreement on the large-scale pattern, offset by weak precipitation signals.
Also Watching
- Aurora Watch: The geomagnetic field has already reached minor (G1) storm levels twice in the past 24 hours, driven by a negative-polarity coronal hole high-speed stream, and forecasters expect another shot at G1 before the day is out, with “mostly active” conditions continuing tomorrow and Friday as the stream wanes. Worth a glance north after dark for anyone in the northern-tier states.
- Fire Weather: No critical areas today — a quiet national map. The one elevated zone: northeastern California, northwestern Nevada, and southern Oregon, where 90–100°F heat, 10–20 percent humidity, and sustained southwesterly winds overlap a receptive fuelscape. Thursday brings a silver lining farther east — increased rain chances over drought-stressed northern Minnesota and Wisconsin ease the fire concern there, while the elevated threat continues across the interior West.
- Marine: A Gale Warning is active in the North Atlantic — a low pressure system near 42N 65W producing 20–30 knot winds and seas to 3.5 meters, moving northeast and expected to absorb into a stronger low near Greenland by the weekend. Mariners on North Atlantic routes should plan around it.
- Drought Monitor: Weekly product; the next national map lands tomorrow, Thursday, August 20 — featured here in full when it drops.
Look Up Tonight
Waxing Crescent · about 42% illuminated
Tonight’s the last night as a crescent — the Moon reaches First Quarter (exactly half-lit) at 10:46 PM EDT. Rises around midday and stays up into the evening, setting around midnight local time (general timing; check local listings for exact times at your location). Mark the calendar for August 27–28: a Full “Sturgeon” Moon paired with a partial lunar eclipse visible across North and South America.
One Cool Thing
That “1–2 inches per hour” rainfall rate forecasters are flagging for tonight’s Ohio Valley storms sounds abstract until you picture the fuel behind it: the column of air over the region is carrying precipitable water — essentially, all the moisture in that column of air condensed into a single puddle — of 2 to 2.25 inches. That’s close to the physical ceiling for what an August airmass can hold. Stack that much moisture over a slow-moving storm, and an hour of rain can genuinely put down two inches.
Shareables
Source Ledger every claim, timed & sourced
Our standard: nothing in this briefing older than 8 hours without a flag. Products that update once daily or weekly are used at their most recent issuance and marked.
| Product | Issued | Status |
|---|---|---|
| WPC Short-Range Forecast Discussion | 4:00 AM EDT Wed Aug 19 | CURRENT |
| WPC Extended (Day 3–7) Forecast Discussion | 3:33 AM EDT Wed Aug 19 | CURRENT |
| WPC Excessive Rainfall Discussion (Days 1–5) | 4:11 AM EDT Wed Aug 19 | CURRENT |
| SPC Day 1 Convective Outlook | 8:54 AM EDT Wed Aug 19 | CURRENT |
| SPC Day 2 Convective Outlook | 1:44 AM EDT Wed Aug 19 | CURRENT |
| SPC Day 3 Convective Outlook | 3:37 AM EDT Wed Aug 19 | CURRENT |
| SPC Day 1–2 Fire Weather Outlooks | 1:38 AM / 1:40 AM EDT Wed Aug 19 | CURRENT |
| NHC Atlantic Tropical Weather Outlook | 8:00 AM EDT Wed Aug 19 | CURRENT |
| NHC East Pacific Tropical Weather Outlook | 8:00 AM EDT Wed Aug 19 | CURRENT |
| CPHC Central Pacific Tropical Weather Outlook | 8:00 AM EDT Wed Aug 19 | CURRENT |
| Hurricane Lala Public Advisory No. 28A | 8:00 AM EDT Wed Aug 19 (2:00 AM HST) | CURRENT |
| Hurricane Lala Forecast Advisory No. 28 | 5:00 AM EDT Wed Aug 19 | CURRENT |
| CPC 6-10 / 8-14 Day Prognostic Discussion | 3:00 PM EDT Tue Aug 18 | CURRENT ISSUANCE · daily product; next ~3–4 PM today |
| SWPC Space Weather Forecast Discussion | 7:55 AM EDT Wed Aug 19 (1155 UTC) | CURRENT |
| OPC High Seas Forecast (METAREA IV, N. Atlantic) | 6:30 AM EDT Wed Aug 19 | CURRENT · situational (active Gale Warning) |
| Moon phase & illumination | — | USNO/NASA, current |
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: Major Hurricane Lala bearing down on the Papahānaumokuākea Marine National Monument · the Ohio Valley’s second major flash-flood threat in two weeks, on ground already saturated · Thursday’s Mid-Atlantic/NYC-metro rain uncertainty and what forecasters are watching to resolve it · the Atlantic’s unusually quiet mid-August while the Pacific runs three systems at once.
BOOKING: kaitlin@coxweatherservices.com · 888-248-9347 · coxweatherservices.com · attribution: “Bob Cox, meteorologist, Cox Weather Services”