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TheForecast Post

A chronicle of American weather and climate  ·  Wednesday, 16 September 2026

Weather Trader Notebook MILEPOST 917

April 12, 2026 Sunday Spring Weather

Very warm week ahead across Eastern U.S. with widespread 80s and 90s

What the month did

April 2026 was the 3rd-warmest April in the 132-year national record (1895–2026), at 54.7°F against a 1991–2020 normal of 51.8°F (+2.9°F).

April 2026 was the 46th-wettest April in the 132-year national record (1895–2026), at 2.7in against a 1991–2020 normal of 2.7in (+0.0in).

NOAA/NCEI Climate at a Glance, contiguous United States. This is the observed record for the month, not a score of anything said in this piece — the forecast ledger begins 2026-08-17 and cannot reach earlier posts.



Congratulations to Rory McIlroy on his back-to-back Masters championship! If you watched the tournament over the past several days, then you saw the absolutely perfect weather conditions — and the course was stunning. This is the best of Georgia in April. It was in the mid-80s in Augusta this afternoon with a slight breeze.

RTMA Current Temperature Analysis | 6:30 PM ET

Lower 48 average was 67.1°F with 194 million at least 70°F

RTMA Current Temperature Anomaly Analysis | 6:30 PM ET

Lower 48 was 7.0°F ABOVE normal


Tropical Update: North Western Pacific

Massive Super Typhoon Sinkalu (04W) has peaked at 155-170 knots … earlier at 09:40 UTC on Sunday with Automated Dvorak T number of 8.0.

The T=8.0 (raw/snapshot) corresponded to Eye temperature of +23°C and convective canopy temperature of -83.1° —> certainly an upper-echelon / very extreme example of tropical cyclone on Earth in recent decades.

2026APR12 094000  7.5  896.4 155.0  7.5 7.6 8.0  1.3T/6hr  OFF  OFF  OFF  OFF  23.00 -83.09  EYE

JTWC official forecast for Sinlaku has curved northward away from Guam and now over Tinian on Wednesday.

HAFS 12z Precipitable Water (my favorite parameter) through 5-days shows Sinlaku turning northward in the next 2-3 days and weakening as it encounters dryer air, cooler SSTs, and upper-level westerlies —> extratropical transition process.

HAFS-A (12z mesoscale hurricane model) for Sinlaku (04W) shows a “behemoth” developing rapidly and moving over Tinian.

Sinlaku will grow even larger in size as the storm completes eyewall replacement cycles. The breadth of the 850 mb Wind Field is in the upper-echelon of global tropical cyclones.

North Atlantic African Dust | Next 10-days

Dust over the north Atlantic and Africa — as any early season tropical waves will be wiped out by dust. We’ll also get a sense of the activity into June by the circulation pattern in the Eastern MDR of the Atlantic, and how dust flows over the ocean.

Lower 48 Weather into Monday Morning

Western U.S. unsettled with rain/snow … SE Texas thunderstorms into evening

HRRR 18z — Radar Simulation Next 48-hours to Tuesday 2 PM ET

Enhanced Risk of Severe Weather in upper-Midwest (Minnesota/Wisconsin) late Monday into early Tuesday.

HRRR 18z Precipitable Water Next 48-hours (my favorite parameter)

Weather on Monday: warm frontal boundary across MN/WI into Great Lakes could see some large supercells with hail threat later on Monday — including Minneapolis.

NDFD NWS Total Precipitation Next 72-hours through Wednesday Afternoon

NWS Snowfall Next 72-hours — through Wednesday Afternoon

ECMWF 12z | Forecast 6-days of Precipitable Water (my favorite parameter)

Moisture streams in multiple surges out of the Gulf of Mexico —> open for business!

ECMWF 12z Precipitation Type + Intensity | Next 8-days

Western U.S. Storm System into California

Atlantic Basin | Next 8-days

Atlantic Basin Precipitable Water next 8-days

Moisture Transport (IVT) next 10-days

Precipitation Surplus centered on Caribbean including Puerto Rico!

Total Precipitation Next 10-days | Blend of Models

Ring of fire pattern with zip/zero rainfall across the Southeast.

Blend of Models | Total Snowfall Next 10-Days

ECMWF AIFS 12z next 10-days of 500 mb Height Anomaly

The Hudson Bay Polar Vortex continues to spin. Eastern ridge breaks down by next weekend

Blend of Models Temperatures | Highs through Tuesday, April 21

Blend of Models Temperatures | Lows through Tuesday, April 21

Low Temperatures Monday

Only 1.75 million below freezing

High Temperatures on Monday

80s for 171 million population from central Plains into Mid-Atlantic … but almost no 90°F yet

High Temperatures on Tuesday

204 million at least 80°F and we add 7 million at least 90°F —> western U.S. cool!

ECMWF AIFS 12z | Temperature at 500 mb | Next 10-days

There’s STILL a -45°C contour of the polar vortex at 500 mb holding on for dear life in Canada for the next 7-10 days, and drifts toward Greenland. Bizarre!

Snowfall from ECMWF HRES (15-days)

Snowfall from ECMWF AIFS-Single (12z) next 15-days

Temperature Anomaly | Next 15-days | ECMWF EPS 12z Ensemble Mean

Week #1 | Temperature Anomaly | April 12 - April 18

Week #2 | Temperature Anomaly | April 19 - April 25


April 7: 2026 Atlantic Seasonal Hurricane Forecast: 11/5/2

9-13 Named Storms (11 most likely)
4-7 Hurricanes (5 or 6 most likely)
1-3 Major Hurricanes (2 most likely)

ACE: 75-85

Maps sourced from weathermodels.com designed and innovated by yours truly! Please subscribe there for real-time access to the newest maps, charts from all of the weather models including ECMWF and AIFS, and NOAA GFS/GEFS. NOAA WPC and SPC for fronts/convective outlooks.

Milepost
917 · laid 2026-04-12T23:33:51.432000Z
Source
https://weather.substack.com/p/april-12-2026-sunday-spring-weather
Digest
5949f9da762c4292f41d2dcb6dbda169d410874c1f49dcb8545d4ca148d60db7
Machine
JSON