Bobgram 18 Jan

Bob McDavitt's ideas for sailing around the South Pacific.
Disclaimer: Weather is a mix of pattern and chaos; these ideas are from the
patterned world.
Compiled 18 Jan 2026

This weekend we had damaging "flash flood" in Sydney and another around
Whangarei

Here are some Key Findings on Hail Trends from The European Severe Storms
Laboratory at essl.org
. Fewer, Bigger Hailstones: Climate change creates stronger updrafts
and more moisture, allowing hailstones to grow larger, even as overall hail
frequency might decrease in some regions, notes a study in Nature Climate
and Atmospheric Science.
. Increased Damage: Rising losses are due to a mix of bigger hail and
more buildings/infrastructure in vulnerable areas (e.g., US, Australia),
making them more susceptible to damage.
. Regional Differences: Europe shows the strongest increase in very
large hail frequency, while some Southern Hemisphere areas see declines
. Record-Breaking Events: The US has seen record-breaking reports of
large hail in recent years (2023, 2024), exceeding previous highs
significantly.
What's Driving These Changes?
. Atmospheric Moisture: More humidity near the surface fuels stronger
thunderstorms, increasing hail size.
. Temperature & Instability: Warmer air supports powerful updrafts
that keep hail suspended longer, allowing it to grow.
. Socio-Economic Factors: More development in hail-prone zones (like
coastal Australia) significantly increases potential losses, even more than
just the weather changes.
What Does This Mean for the Future?
. Expect more powerful, damaging hailstorms in some areas, with
significant economic impacts.
. Insurance, building codes, and urban planning will need to adapt to
this growing risk.


TROPICS

. Australia's northern Queensland coast was drenched with some of the
heaviest rain since 1916 from Tropical Storm Koji and its remnants.
. Cyclone Dudzai, which briefly reached Category-4 strength, formed over the
central Indian Ocean. Cyclone Nokean is hovering east of the Philippines.
A new tropical depression name with token name 94P has been picked up by the
computer models expected to travel steadily to southeast reaching Northland,
New Zealand on Thursday.


WEATHER ZONES

Rain accumulation this week from Windy.com above shows well defined tracks
of rain associated with a few Lows L1 and L2 described below.

Wind accumulation from windy.com above shows tracks of wind associated with
Lows L1 and L2. Northern NZ seems to be a place to AVOID this week .
Highs and LOWS
The Low L1 to east of Northland tonight which was responsible with
yesterday's deluge near Whangarei is expected to travel east until Wednesday
and then stall and maybe travel to SW if caught in the circulation around
L1.
The Tropical depression L2 tonight in the Coral Sea may well earn a Cyclone
name soon and is expected to travel southeast reaching northern NZ on
Thursday. Avoid.

Another low over inland Australia is expected to travel slowly east this
week.

The subtropical ridge is this week well south of its normal position. Highs
are travelling east along around 45S. High H1 is expected to squeeze past
southern NZ on Monday to Wednesday/ High H2 should spread east into the
Sussie Bight reaching Tasmania on Friday.

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