CPAC: NORMAN - Post-Tropical

[DioBrando]

Still, despite the EWRC, who here thinks Norman is so handsome?

I mean for an 2018 EPAC storm.

[Kingarabian]

Norman is a great looking system for sure. We're just fatigued from Hector and Lane so we're not ooing and awwing as much.

[DioBrando]

Norman is a great looking system for sure. We're just fatigued from Hector and Lane so we're not ooing and awwing as much.

Makes sense bruh

[wxmann_91]

These storms that dip south of west seem to be destined for Cat 5 status. Matthew dipped south of west in 2016, Irma did it last year, Lane moved at 265 degrees for a little while during his tropical storm stage, and now Norman is forecast to reach Cat 5 and his south of west dip is becoming quite evident on satellite loops. Honestly, I think if recon were flying this storm, they would probably find Cat 5 winds already. 145kts SFMR values wouldn't surprise me.

I would've agreed with this 4.5 hours ago but as Norman dips south of west his spunk is failing. Its not just the cloud tops warming, its his eye is failing to clear out fast enough and that odd flattening on the east side is continuing. The evolution of the NE quad is also suspect.

Its too bad that Norman peaked under 140 (135 is still on the table). Once Norm finishes his eye and enters less favorable conditions I'm dropping this from my registrar like a hot potato.

It does look like Norman is suffering from some easterly shear. Not too atypical of storms moving south of west. Usually they bottom out when they round the curve.

[Yellow Evan]

----- Current Analysis -----
Date : 30 AUG 2018 Time : 223000 UTC
Lat : 17:30:00 N Lon : 119:00:00 W


CI# /Pressure/ Vmax
6.8 / 930.1mb/134.8kt


Final T# Adj T# Raw T#
6.5 6.6 6.6

Estimated radius of max. wind based on IR : 17 km

Center Temp : +11.0C Cloud Region Temp : -70.4C

Scene Type : EYE

[Yellow Evan]

CDO rebounding but eye is cooling and no longer WMG. T6.5.

[Yellow Evan]

[Cyclenall]

It does look like Norman is suffering from some easterly shear. Not too atypical of storms moving south of west. Usually they bottom out when they round the curve.

What's funny is I was just thinking if I was on twitter I was going to tweet to you the question as to why the east part of Norman looks disheveled . I feel like a future ERC will be poorly timed for Norm to get to 140.

C'mon Cyclenall lol. Norman has time... about 4 days left of ideal conditions to become a formidable Cat.5.

I thought he only had 12-24 hours left of ideal conditions? I could believe a maintenance of 130 knots during the next 96 hours but otherwise a downtrend.

[Yellow Evan]

----- Current Analysis -----
Date : 30 AUG 2018 Time : 233000 UTC
Lat : 17:26:24 N Lon : 119:08:23 W


CI# /Pressure/ Vmax
6.8 / 930.1mb/134.8kt


Final T# Adj T# Raw T#
6.5 6.5 6.5

Estimated radius of max. wind based on IR : 16 km

Center Temp : +12.5C Cloud Region Temp : -69.8C

Scene Type : EYE

[Chris90]

Storms like Norman make me really wish we had drones flying out in these EPAC storms taking intensity measurements or that CYGNSS was fully operational and they were using it to determine maximum surface winds. I'm in agreement with the others that think the time is quickly passing when he can receive the official Cat 5 designation.
Dvorak is a really great tool, but we've seen before where it can underestimate intensity in some higher end storms and I think Norman might be another victim of that.
Ah, well. Still been an amazing season so far.

[Yellow Evan]

T6.5. E aside fell apart.

[Yellow Evan]

TXPZ26 KNES 310018
TCSENP

A. 16E (NORMAN)

B. 31/0000Z

C. 17.4N

D. 119.2W

E. ONE/GOES-W

F. T6.0/6.0/D1.5/24HRS

G. IR/EIR/VIS

H. REMARKS...WMG EYE IS EMBEDDED IN LG AND SURROUNDED BY W RESULTING
IN AN ENO OF 5.0 AND AN EYE ADJUSTMENT OF 1.0 FOR A DT OF 6.0. PT AND
MET ARE ALSO 6.0. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL

Should be embedded in B. SAB off by a half a T number.

[cycloneye]

Hurricane Norman Discussion Number 12
NWS National Hurricane Center Miami FL EP162018
800 PM PDT Thu Aug 30 2018

After the explosive intensification observed last night and
earlier today, Norman's intensity has leveled off. The eye of the
major hurricane remains quite circular and distinct with a
solid eyewall surrounding the center. The eastern portion of the
eyewall, however, has eroded a little during the past few hours.
Based on the steady state appearance, the initial intensity is held
at 130 kt, which lies at the upper end of the satellite intensity
estimates.

The environmental conditions surrounding Norman are expected to
only gradually become less favorable with SSTs and mid-level
humidity values slowly decreasing along Norman's track during the
next few days. There is a possibility of eyewall replacement cycles
in major hurricanes like Norman, which typically cause fluctuations
in strength and are challenging to forecast. The intensity models
all show a slow weakening trend, and the NHC forecast follows that
theme. This forecast is slightly below the previous one, trending
toward the latest consensus models.

Norman is moving west-southwestward at 8 kt steered by a
northeast-southwest oriented deep-layer ridge to the north of the
tropical cyclone. This general motion is expected to continue for
the next day or so. After that time, a change in the orientation
of the ridge should cause Norman to turn to the west and then
west-northwest with an increase in forward speed. The track models
remain in relatively good agreement, and the NHC track forecast lies
near the middle of the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT 31/0300Z 17.3N 119.6W 130 KT 150 MPH
12H 31/1200Z 17.0N 120.7W 125 KT 145 MPH
24H 01/0000Z 16.6N 122.3W 120 KT 140 MPH
36H 01/1200Z 16.2N 124.3W 110 KT 125 MPH
48H 02/0000Z 16.3N 126.3W 105 KT 120 MPH
72H 03/0000Z 17.8N 131.5W 95 KT 110 MPH
96H 04/0000Z 19.5N 137.0W 75 KT 85 MPH
120H 05/0000Z 20.5N 142.0W 60 KT 70 MPH

$$
Forecaster Cangialosi

[Kingarabian]

What a collapse...



Shear looked completely normal, both in the upper and mid levels on CIMSS... Looks to be about 10-15kts of easterlies hitting it. Might suffer until it regains its westerly heading.

[Kingarabian]

00z Euro has a stronger ridge and recurves it closer to the Big island:

[cycloneye]

Hurricane Norman Discussion Number 13
NWS National Hurricane Center Miami FL EP162018
200 AM PDT Fri Aug 31 2018

Norman appears to have weakened over the past several hours. Cloud
tops around the eye have warmed, and the eye itself has become less
distinct. Several recent microwave overpasses show little indication
that an eyewall replacement cycle is underway, but it is possible
that our ability to observe such a cycle is limited by the
resolution of the available instruments. Satellite intensity
estimates from all agencies have decreased and supported at most an
intensity of 125 kt at 0600 UTC. Given the continued warming of
cloud tops near the inner core since that time, the initial
intensity has been lowered to 120 kt.

Due to the lower initial intensity, the intensity forecast has also
been lowered slightly, particularly for the first 24 h. Gradual
weakening is expected through the forecast period, though larger
short-term fluctuations in intensity due to eyewall replacement
cycles are possible, if not likely, while Norman remains a
hurricane. By the end of the forecast period, a faster weakening
rate is anticipated as Norman is forecast to move over cooler SSTs
and reach a drier environment. The NHC forecast is near the center
of the intensity guidance envelope and near the intensity consensus.

The hurricane has continued to move west-southwestward at 8 kt.
Almost no change has been made to the track forecast, which remains
close to the various consensus aids. The hurricane should turn
westward, and then west-northwestward, as it is steered primarily by
a deep-layer ridge to the north for the next 5 days. With the
exception of the UKMET global model, which is an outlier to the
south, the global and regional dynamical models are in good
agreement on the future path of Norman, and confidence in the track
forecast is fairly high.


FORECAST POSITIONS AND MAX WINDS

INIT 31/0900Z 16.9N 120.2W 120 KT 140 MPH
12H 31/1800Z 16.6N 121.4W 110 KT 125 MPH
24H 01/0600Z 16.3N 123.1W 110 KT 125 MPH
36H 01/1800Z 16.3N 125.1W 105 KT 120 MPH
48H 02/0600Z 16.7N 127.4W 100 KT 115 MPH
72H 03/0600Z 18.4N 133.0W 85 KT 100 MPH
96H 04/0600Z 19.5N 139.0W 70 KT 80 MPH
120H 05/0600Z 20.5N 143.5W 55 KT 65 MPH

$$
Forecaster Zelinsky

[cycloneye]

Hurricane Norman Discussion Number 14
NWS National Hurricane Center Miami FL EP162018
800 AM PDT Fri Aug 31 2018

Norman appears to be undergoing an eyewall replacement cycle.
Although a lack of earlier microwave imagery hasn't helped to
support this speculation, enhanced infrared BD-Curve images,
however, revealed a collapse of the inner core in the northeast
quadrant several hours ago. Currently, that portion of the
eyewall has begun to fill in with a solid ring completely
surrounding the eye, albeit, rather thin. Consequently,
subjective and objective T-numbers, as well as an earlier SATCON
analysis, support a slight decrease of the initial intensity to 115
kt.

Further slow weakening is forecast through the entire period,
although there could be fluctuations in the short-term due to the
aforementioned inner core structure evolution. There also appears
to be some modest northeasterly shear impinging the northeast
portion of the cyclone, which could hamper strengthening. The Decay
SHIPS intensity model indicates that the shear will persist during
the next couple of days. Through the remaining part of the
forecast, decreasing SSTs and the intrusion of a more stable/drier
environment from the north should lead to further weakening. The
NHC forecast is similar to the previous one, and follows the
NOAA-HCCA and IVCN intensity consensus models.

The initial motion is estimated to be west-southwest, or 245/7 kt.
The cyclone's motion is currently influenced by a
northeast-southwest oriented mid-to-upper tropospheric ridge
residing between Hurricane Miriam to the west, and Norman to the
east. This current motion is expected to continue for
the next 36 hours, or so. Afterward, the ridge between the two
tropical cyclones is expected to weaken as Miriam continues on a
generally northward track. This change in the synoptic steering
pattern should cause Norman to turn to the west and then
west-northwest with an increase in forward speed. The official
forecast has changed little over the past 6 hours and is based on a
blend of the HCCA and TVCN consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT 31/1500Z 16.7N 120.8W 115 KT 130 MPH
12H 01/0000Z 16.4N 122.0W 105 KT 120 MPH
24H 01/1200Z 16.2N 123.8W 100 KT 115 MPH
36H 02/0000Z 16.3N 125.9W 95 KT 110 MPH
48H 02/1200Z 16.8N 128.6W 90 KT 105 MPH
72H 03/1200Z 18.3N 134.4W 80 KT 90 MPH
96H 04/1200Z 19.5N 140.0W 70 KT 80 MPH
120H 05/1200Z 20.5N 144.0W 60 KT 70 MPH

$$
Forecaster Roberts

[Ntxw]

Early visible shows Norman not what he was 24 hours ago. Perhaps when his heading is back west to wnw he might make a short recovery. His golden days are likely past and may be future Olivia's time to shine for a period. The NHC forecast could muster another ~10 units or so on top of the ~10 now.

[Kingarabian]

CDO recovering and building to the NE in the past few frames:

[cycloneye]

Hurricane Norman Discussion Number 15
NWS National Hurricane Center Miami FL EP162018
200 PM PDT Fri Aug 31 2018

Satellite derived mid and upper tropospheric winds and the UW-CIMSS
shear analysis indicate that the persistent northeasterly vertical
shear has increased to 20-25 kt, and has continued to impede outer
deep convective banding development in the northern portion of
Norman's inner core. The cloud pattern has also become somewhat
asymmetric (northeast to southwest). A series of recent microwave
images, however, show that the eyewall is now closed, although the
eye temperature has warmed a bit during the past 6 hours. The
Dvorak satellite intensity classifications from TAFB and SAB also
support these observations, and the initial intensity is reduced to
110 kt.

Although there may still be some fluctuations in intensity, gradual
weakening is forecast through day 5, primarily due to the shear
predicted by the GFS and ECMWF Decay-SHIPS intensity models.
Intrusion of stable air mass, beyond day 3, northeast of the
Hawaiian Islands will also promote this weakening trend. The
official intensity forecast has changed little from the previous
advisory, and is still based on the HFIP Corrected Consensus
Approach and IVCN intensity models.

The initial motion is estimated to be west-southwest, or 255/7 kt.
An anchored mid- to upper-level ridge that stretches
west-southwestward from the Baja California peninsula should steer
Norman west-southwestward during the next 12 hours or so.
Afterward, the southwestern-most segment of the ridge axis between
Miriam and Norman weakens as Miriam continues on a northward track.
This change in the synoptic steering pattern should influence Norman
to turn back toward the west or west-northwest by early next week.
Only slight along-track speed adjustments were made to this
advisory, which follows a blend of the HCCA and TVCN consensus
guidance.

FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 16.5N 121.5W 110 KT 125 MPH
12H 01/0600Z 16.2N 122.6W 100 KT 115 MPH
24H 01/1800Z 16.2N 124.4W 95 KT 110 MPH
36H 02/0600Z 16.6N 127.0W 90 KT 105 MPH
48H 02/1800Z 17.3N 129.9W 85 KT 100 MPH
72H 03/1800Z 18.9N 136.0W 80 KT 90 MPH
96H 04/1800Z 20.0N 141.1W 70 KT 80 MPH
120H 05/1800Z 20.9N 144.7W 65 KT 75 MPH

$$
Forecaster Roberts