Aviation weather thread

JCX BXC

Back to snow again, moderate snow at 10pm.

JCX BXC

Snow was removed from the TAF of Cork at 11pm, yet its been snowing since.
Fairly poor forecasting.

Growler!!!

Carnacalla wrote: »

Snow was removed from the TAF of Cork at 11pm, yet its been snowing since.
Fairly poor forecasting.

Careful now, read it again:

TAF: EICK 262300Z 2700/2724 02017G28KT 9999 SCT005 BKN010 TEMPO 2700/2708 3000 -RA SCT003 BKN006 PROB40 TEMPO 2700/2703 1500 RASN SCT001 BKN003 BECMG 2702/2704 04013KT BECMG 2721/2723 35005KT

40% chance of rain and snow from midnight to 3am.

JCX BXC

Rain snow being sleet?
There's a distinctive difference between Sleet and Snow.

At least that's how In understand it. When you have RASN reported in a Metar its sleet.

Growler!!!

Carnacalla wrote: »

Rain snow being sleet?
There's a distinctive difference between Sleet and Snow.

At least that's how In understand it. When you have RASN reported in a Metar its sleet.

Haha you're being pedantic now. Is it not snowing? Between midnight and 3?

JCX BXC

Growler!!! wrote: »

Haha you're being pedantic now. Is it not snowing? Between midnight and 3?

Not really though.

RA
RASN
SN
All different things, of course I don't have the qualifications to say how much the difference between RASN and SN is important, but still there is a fairly large difference. Sleet is almost depressing, whereas snow is fun!

Gaoth Laidir

Carnacalla wrote: »

Not really though.

RA
RASN
SN
All different things, of course I don't have the qualifications to say how much the difference between RASN and SN is important, but still there is a fairly large difference. Sleet is almost depressing, whereas snow is fun!

In Table 4678 of the WMO's official Manual on Codes 306 there is no official code for "Sleet" as we know it here (a mix of rain and snow or melting snow). In the US their sleet is our Ice Pellets (PL), which are translucent balls of ice. The NWS in the US does officially use the word Sleet for Ice Pellets.

RASN in a METAR is used to mean a mix of Rain and Snow, both occurring at equal probability. Yes, this is what we colloquially call Sleet.

So if a TAF calls for RASN then individual METARS during that period could show either RA, SN or RASN (a mix of rain and snow).

Anyway, it did turn out to be more snow than rain at Cork as the synops reported 2 cm of lying snow between 2 and 4 am.

Pat Dunne

Gaoth Laidir wrote: »

In the US their sleet is our Ice Pellets (PL), which are translucent balls of ice. The NWS in the US, however, does officially use the word Sleet for Ice Pellets.

Are Ice Pellets, what we refer to as Hail / Hail Stones in this part of the world?

Gaoth Laidir

Pat Dunne wrote: »

Are Ice Pellets, what we refer to as Hail / Hail Stones in this part of the world?

No, hail is opaque and given the code GR (diameter >5 mm) or GS (<5 mm). Hail forms by a totally different process.

Ice Pellets form when there is a warm layer a couple of thousand feet up, with a sub-zero layer below it down to the surface. Snow from above the warm layer semi-melts in the warm layer but then refreezes in the surface layer.

calnand

Currently sitting on a plane at cork, waiting for the runway to be cleared of snow, they said 20mm is remaining after two sprays they're attempting one more before deciding to scrape it.

Growler!!!

No take offs or landings for over 2 hours, now one in the hold. All down to snow and ice. Why hasn't a SNOCLO been issued in the metar? Or even a snowtam?

Gaoth Laidir

Growler!!! wrote: »

No take offs or landings for over 2 hours, now one in the hold. All down to snow and ice. Why hasn't a SNOCLO been issued in the metar? Or even a snowtam?

I was wondering that myself. At least one or the other or runway contamination details on the METARs.

Strang, though, that the 7 and 8 am synops only reported <1 mm of lying snow.

pepe the prawn

I take TAF's to be an indication of what weather conditions may exist in an area over a particular period of time. Weather forecasting is a dark art, and so if a taf says RA SN, then I'd be planning for rain, sleet, snow, and any other associated conditions.

I remember last year when the weather was CAVOK at ORK, WAT and SNN, yet instructors wouldn't let students off to do solo navs because the visibility was so poor with haze, yet it wasn't in the METARS, vis was actually stated as being 9999. Even though realistically it was probably around 5-6k at best.

It must be remembered that forecasts are just that, forecasts. They are not definitive statements of the exact conditions that will be present at a particular time, they are predictions. And just because it says RA SN in the TAF, doesn't mean that you will only get sleet and no snow.

JCX BXC

I understand the bit about them only being forecasts, which are in essence only predictions. Its the fact that when the forecast was made it was snowing, and was for hours before and after. Yet this was not reflected in the TAF

Growler!!!

Carnacalla wrote: »

I understand the bit about them only being forecasts, which are in essence only predictions. Its the fact that when the forecast was made it was snowing, and was for hours before and after. Yet this was bit reflected in the TAF

Ah here, you're going to be SLEETING on about this all day!:D:):D

I'll get my coat...........................

Gaoth Laidir

Carnacalla wrote: »

I understand the bit about them only being forecasts, which are in essence only predictions. Its the fact that when the forecast was made it was snowing, and was for hours before and after. Yet this was bit reflected in the TAF

I agree. Although past weather does not guarantee future returns, the TAF should have at least mentioned PROB40 SN. There was a half a degree either way between snow and rain/sleet, call it whatever, but there were several hours of SN reports overnight and as such this led to delays this morning.

Not that a different TAF would have made one blind bit of difference to the actual weather that happened. If only!!

JCX BXC

Currently Snowing at BFS.

Snow in the TAF's for DUB,NOC and BFS.

Gaoth Laidir

Gust of 60 kts in the last hour at Casement.

PsMETAR BALD 020700Z 28041G60KT 9999 -SHRA SCT015 OVC026 02/01 0993 MSL=

Gaoth Laidir

3 mm of wet snow on the runway at DUB this morning. There seem to have been a few delays

Gaoth Laidir

Severe frost warnings out for DUB and BAL up to 09Z. May cause deicing delays at DUB.

●EIME AD WRNG 01 VALID 052100/060900 FROST SEV GND AND MOD AIR DEPOSITIONS LIKELY FCST =
●EIDW AD WRNG 01 VALID 052000/060900 FROST SEV GND AND MOD AIR DEPOSITIONS LIKELY FCST =

Not as bad at the other airports.

●EINN AD WRNG 01 VALID 052100/060800 FROST MOD GND AND FBL AIR DEPOSITIONS LIKELY FCST =
●EICK AD WRNG 01 VALID 052100/060900 FROST MOD GND AND FBL AIR DEPOSITIONS LIKELY =
●EIKN AD WRNG 01 VALID 052100/060900 FROST FBL GND AND FBL AIR DEPOSITIONS LIKELY FCST =

JCX BXC

Here's something we haven't seen in a while, the famous fog at Cork.

EICK 102130Z 21006KT 0600 R17/0900D R35/0700D FG BKN001 OVC002 09/09 Q1025 NOSIG

JCX BXC

Fog Back again at Cork, and fairly dense this time!

EICK 111730Z 21009KT 0300 R17/0400N R35/0350N -DZ FG OVC001 09/09 Q1024 TEMPO 0600.

JCX BXC

Operations may be slowed at Dublin this evening,

The 5pm TAF reports tempo fog with a vis of 0400m from 8pm-10am tomorrow.

6pm Metar reports also gives fog in the vicinity.

Gaoth Laidir

The sky here is a brilliant orange as mist is already starting to form. Dewpoints are 6-7 °C so plenty of scope for thick fog tonight. Could be slow to clear tomorrow too.

smurfjed

OEJN 270800Z 18028KT 0500 SS VV/// 37/15 Q1006 TEMPO 0200

Gotta love sand storms :)

Gaoth Laidir

Fog pretty widespread around the country this morning.

100 m - Knock
200 m - Baldonnel
300 m - Shannon
700 m - Kerry

JCX BXC

Gaoth Laidir wrote: »

Fog pretty widespread around the country this morning.

100 m - Knock
200 m - Baldonnel
300 m - Shannon
700 m - Kerry

Fog at Kerry is something not so often seen.

JCX BXC

Fog Warning for Connacht, Leinster, Cavan, Monaghan, Donegal, Cork, Limerick, Tipperary and Waterford
Widespread fog overnight and on Wedeneday morning, dense in many areas.

Issued:Tuesday 12 April 2016 20:00
Valid:Wednesday 13 April 2016 00:01 to Wednesday 13 April 2016 12:00

Could be interesting, as 3 of Ireland 4 major airports are in this warning, and Shannon is very close to Limerick.

roundymac

Cork was ok this morning, the EI AMS flight woke me at 06.05 as it "thundered" overhead.;):rolleyes:

JCX BXC

roundymac wrote: »

Cork was ok this morning, the EI AMS flight woke me at 06.05 as it "thundered" overhead.;):rolleyes:

The expected fog did not happen at anywhere near the expected extent. The fog warning was removed by 8am this morning.