Meteorologists have called stagnant pressure conditions with inflated temperatures “stagflation” for as long as I can remember, which is not that long. Anyway, that’s what we have before us, pretty much the same old thing, day after day, except for some really nice Cirrus patterns in the sky to go with those 100-110 F temperatures we get this time of year. You can see the upper level moisture stream coming over us here, from the Huskies, if you’re interested.
Mind-starting to drift off center now….
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Weather extreme note
If you noted the record-tying “trace” of rain at Vegas back on the 25th and were pretty happy about it, well, you’re going to be put out by this NWS message, passed along by climate guru and mischief maker, Mark Albright, just yesterday. Apparently, the NWS has been concerned over this record tying event for some time:
“RECORD EVENT REPORT…CORRECTED
NATIONAL WEATHER SERVICE LAS VEGAS, NV
1059 PM PDT THU MAY 29 2014
…NO RECORD DAILY MAXIMUM PRECIPITATION WAS TIED AT LAS VEGAS
SUNDAY...
DUE TO AN EQUIPMENT ISSUE WITH THE PRESENT WEATHER SENSOR AT THE
MCCARRAN INTERNATIONAL AIRPORT ASOS, A FALSE REPORT OF A TRACE OF
PRECIPITATION WAS REPORTED ON SUNDAY, MAY 25TH. AFTER FURTHER
INVESTIGATION, THIS WAS DETERMINED TO BE INCORRECT. THEREFORE THE
FINAL PRECIPITATION TOTAL FOR SUNDAY, MAY 25TH, IS 0.00 INCH AND THE
DAILY PRECIPITATION RECORD WAS NOT TIED.
THE ABOVE INFORMATION IS PRELIMINARY AND IS SUBJECT TO A FINAL
REVIEW BEFORE BEING CERTIFIED BY THE NATIONAL CLIMATIC DATA CENTER.
$$”
Hope I didn’t spoil your morning.
On the other hand, you wonder what the NWS meant, “after further investigation…”? What might they have done to remove an extreme weather event, one that tied a record?
Let’s “jump in” and see what we can find out about this record-tying mystery. First, let’s pull up radar-derived precip maps for May 25th and May 26th and see if there is any chance it rained on the 25th. We have to do two maps since the end time of each radar precip map is for the 24 h period ending at 5 AM, whilst the record is for midnight to midnight of the 25th. Below, from WSI Intellicast are those two 5 AM AST maps in chronological order:
:
We can see that it DID rain in the 24 h ending at 5 AM AST on the 25th at McCarran Field, LAS, but not AFTER 5 AM ending on the 26th (map on the right.
But when did the weather observing machine think it rained?
By pulling up the hourly observations in text form below, we can see that the machine thought that rain began at 1519 Central Universal Time (8:19 AM AST) and rained for 11 minutes, ending at 1530 CUT. “RAB” means “rain began, truncated to minutes after the hour).
25 1456 SA KLAS >120 SCT 10 1011.1 77 45 0 0 29.92 1 10 0 0 AO2
25 1556 SA KLAS >120 CLR 10 1011.3 79 44 160 4 29.93 T AO2 RAB19E30
25 1656 SA KLAS >120 SCT 10 1011.0 82 43 3 29.92 0 AO2
25 1756 SA KLAS >120 SCT 10 1010.6 84 42 5 29.91 85 70 8 04 0 T AO2
Looking further, we can also see the text words “SCT” and “CLR” for the time periods in which rain was reported. Furthermore, the the “numbol”, “>120” , means no clouds below 12, 000 feet above ground level.
Can it rain to the ground from clouds higher than 12,000 feet above the ground? Its fairly rare, but it happens, as we Arizona sunbirds know from just the past couple of days when sprinkles fell from such clouds.
However, investigating even farther, we find that the machine is also indicating “CLR” or “SCT” conditions, meaning CLEAR or SCATTERED clouds above 12,000 feet.
Can it rain from CLEAR skies, too few clouds for the sensor to detect overhead? Or SCT skies? It has happened that the machine reports SCT conditions on a RARE occasion when a little Cumulonimbus is passing overhead. I think it was reported from Douglas last summer; thunder, too. Very odd, but not impossible.
But what we don’t see is any “VCRA” report, that is, the coding for “rain in the vicinity” that would be inserted next to the column of “10s” above if there had been any as detected by radar.
So, after a few hours of investigation, we have absolved the NWS of having improperly removed an extreme weather event: the trace of rain was, in FACT, erroneously reported from the McCarran Field weather observing machine.
(Actually the point of this rather tortured writeup is to expose you to a little of our weather reporting language called, METAR. You can read about it here pretty good. You can get those METAR reports from many places, here’s one.
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A hodge-podge of cloud scenes from the recent trace of rain rainy day
(Counted over 100 drops on a wide area of pavement during the many, many sprinkle episodes two days ago; each one, I noticed, dried up in about two seconds, too.)
The End.
