May Weather Discussion.

General Weather Discussions and Analysis
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May Weather Discussion.

Post by wxdata » Mon Apr 26, 2010 2:39 pm

HPC's QPF is painting a rather wet picture for the start of May. A stark reversal to the last two months. Main culprits- a trough to the west, a stalling front and Gulf moisture...
Last edited by srainhoutx on Sat May 15, 2010 4:44 pm, edited 2 times in total.
Reason: By srainhoutx to change title

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Re: May Weather Discussion- A Wet Start?

Post by Ptarmigan » Mon Apr 26, 2010 6:09 pm

Top 10 Driest Aprils on record.
http://www.srh.noaa.gov/hgx/?n=climate_iah_top10_apr

Top 10
Driest
0.33 1937
0.39 1920
0.43 1983
0.47 1987
0.56 1984
0.57 1978
0.58 1944
0.63 1933
0.69 1951
0.70 1907

Here is the total from May to August
10.24 1937
NA 1920
27.31 1983
20.97 1987
12.07 1984
19.53 1978
18.92 1944
18.01 1933
9.71 1951
23.93 1907

Guess what? May to August is wet, with the exception of 1937 and 1951, which we had a drought that time. 1920 is unknown due to data not being available.

Current April total is 2.76. April 1989 was dry, even drier than April 2010. It ended up being one of the wettest May and June ever recorded at Intercontinental Airport.
1989
April=1.48
May=13.56
June=16.28
July=1.92
August=2.74
Total=34.5

May of 1907 is the wettest May ever recorded officially in Houston.
http://www.srh.noaa.gov/hgx/?n=climate_iah_top10_may

What does a dry April mean for us? Historically based on the top 10 dry Aprils, it has given way to wet May and even wet summers. So, we could see a wet May and summer this year. I will come up with a comprehensive April stats at a later date, but it gives you a good idea about what a dry April leads to.

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Re: May Weather Discussion- A Wet Start?

Post by srainhoutx » Tue Apr 27, 2010 5:49 am

Still appears to be some timing issues regarding this weekend...SPC 4 - 8 Day Outlook...

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0325 AM CDT TUE APR 27 2010

VALID 301200Z - 051200Z

...DISCUSSION...
DRASTIC DIFFERENCES BETWEEN THE GFS AND ECMWF ARE AGAIN APPARENT
THIS FORECAST...AS EARLY AS DAY 4 /FRI. APR. 30/. SUBSTANTIAL
DISAGREEMENT BETWEEN THE MODELS IN THE EVOLUTION OF THE COMPLEX
UPPER SYSTEM AFFECTING THE WRN AND CENTRAL U.S. RESULTS IN A GFS
FORECAST OF THE DAY 4 AFTERNOON SURFACE FRONTAL POSITION FROM STL
SWWD INTO SERN TX. MEANWHILE...THE ECMWF DEPICTS THE FRONT AT THE
SAME TIME ACROSS CENTRAL KS/CENTRAL OK/CENTRAL TX.
WHILE SEVERE
POTENTIAL WILL LIKELY EXIST INVOF THE SURFACE FRONT REGARDLESS OF
ITS ACTUAL LOCATION -- AS AMPLY MOIST/UNSTABLE WARM SECTOR WOULD
LIKELY EXIST ALONG WITH FAVORABLE SHEAR...THE LOCATION OF THIS
THREAT WOULD OBVIOUSLY DIFFER BY SEVERAL HUNDRED MILES BASED ON A
PERFECT PROG OF THE TWO RUNS.


ATTM...IT WOULD APPEAR THAT THE ECMWF SOLUTION IS MORE LIKELY --
WITH MAIN SEVERE POTENTIAL EXTENDING FROM PARTS OF IA ACROSS MO/ERN
KS AND INTO OK AND PERHAPS N TX. HOWEVER...ATTM CONFIDENCE IS NOT
HIGH ENOUGH TO HIGHLIGHT A SPECIFIC THREAT AREA.

SUBSTANTIAL MODEL DIFFERENCES CONTINUE THROUGH THE MEDIUM
RANGE...AND THEREFORE CONFIDENCE IS LIKEWISE INSUFFICIENT TO WARRANT
ANY THREAT AREAS THROUGH THE END OF THE PERIOD.

..GOSS.. 04/27/2010
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Re: May Weather Discussion- A Wet Start?

Post by wxdata » Tue Apr 27, 2010 11:02 pm

Although there are timing and location differences of the western trough, most models continue to paint a more cloudy and on again, off again rain picture through early next week..

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Re: May Weather Discussion- A Wet Start?

Post by wxdata » Wed Apr 28, 2010 9:47 am

HPC's still having trouble place its bull-eye for rain maximum, slips parts of SE TX back into the 1 inch totals or greater category by Monday morning.

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Re: May Weather Discussion- A Wet Start?

Post by srainhoutx » Wed Apr 28, 2010 4:22 pm

Interesting snip from HGX this afternoon. Stalled boundaries and deep tropical moisture...hmmm...must be getting close to "Season"... ;)

A DEEP LONGWAVE TROUGH WILL DEVELOP OVER THE WESTERN STATES BY THE
WEEKEND INTO EARLY NEXT WEEK...WITH A STRONG UPPER RIDGE
DEVELOPING OVER THE EASTERN GULF AND FLORIDA IN RESPONSE TO THIS.
IN BETWEEN THESE TWO FEATURES WILL BE A BROAD SWATH OF
SOUTHWESTERLY FLOW ALOFT OVER TEXAS...WITH A SERIES OF SHORTWAVES
PASSING ACROSS THE STATE. THE FIRST DISTURBANCE WILL PUSH THROUGH
THE STATE ON FRIDAY. UPPER FLOW WILL BECOME DIFFLUENT OVER THE
AREA AS 110 KT JET MAX AT 300 MB APPROACHES FROM THE WEST. GFS
BUFR SOUNDINGS SHOW PLENTY OF MOISTURE IN PLACE FRIDAY WITH PWS OF
1.4-1.6 INCHES. HOWEVER...A STRONG CAP WILL BE IN PLACE IN THE
700-800 MB RANGE. AT THE VERY LEAST EXPECT SOME SHALLOW CONVECTION
TO DEVELOP UNDER THE CAP. THE BEST CHANCE OF THE CAP BREAKING WILL
BE OVER THE NE ZONES...AND STRONG SHEAR IN THE LOW LEVELS WOULD
SUPPORT AN ISOLATED SEVERE THREAT IN THIS AREA. SPC HAS A SLIGHT
RISK FOR THE NE HALF OF THE AREA. WILL HAVE HIGHEST POPS (40S/50S)
OVER NE ZONES TAPERING DOWN TO 20S ALONG THE COAST. AN EVEN
STRONGER SHORTWAVE PUSHES THROUGH NORTH TX ON SATURDAY.
HOWEVER...BY THIS POINT THE CAPPING BECOMES EVEN STRONGER OVER THE
CWA...AND MID LEVEL TEMPS ARE QUITE WARM (500 MB TEMPS AROUND
-6C). GIVEN THE DEEP MOISTURE IN PLACE...WILL MAINTAIN LOW POPS
(20S/30S) SATURDAY FOR SHALLOW CONVECTIVE DEVELOPMENT.
HOWEVER...THINKING THAT SEVERE WEATHER THREAT SATURDAY WILL REMAIN
NORTH OF THE AREA. SFC DRYLINE WILL LIKELY REACH NW ZONES LATE
SATURDAY THEN STALL BEFORE RETREATING BACK TO THE WEST ON SUNDAY.
MOISTURE LEVELS DEEPEN FURTHER SUNDAY/MONDAY AS THE LOW LEVEL JET
BEGINS TO TAP INTO SOME TROPICAL MOISTURE. PWS INCREASE TO 1.6-1.8
INCHES THIS PERIOD. CAPPING ALSO APPEARS TO WEAKEN SOMEWHAT THIS
PERIOD. HAVE MAINTAINED 20-30 POPS ACROSS THE AREA WITH THE
ANTICIPATION OF SCATTERED DIURNAL CONVECTIVE DEVELOPMENT. UPPER
TROUGH FINALLY BEGINS TO MOVE ACROSS TEXAS LATE MONDAY AND
TUESDAY...PUSHING A WEAK COLD FRONT THROUGH THE AREA. BOTH THE GFS
AND ECMWF INDICATE THIS COULD BE A VERY WET PERIOD FOR SE TX...AS
PWS INCREASE TO OVER 2 INCHES...AND GOOD CONVERGENCE DEVELOPS
ALONG THE SFC AND 850 MB BOUNDARIES. FOR NOW HAVE KEPT POPS AT LOW
CHANCE CATEGORY BUT MAY NEED TO RAISE THEM LATER ON.

FOR THE ENTIRE PERIOD FROM FRIDAY THROUGH EARLY NEXT WEEK EXPECT
HUMIDITY TO BE AT SUMMERTIME LEVELS WHICH WILL SEEM LIKE QUITE A
SHOCK AFTER SUCH A COOL WINTER AND SPRING. SKIES WILL REMAIN
MOSTLY CLOUDY WITH BREEZY CONDITIONS AS WELL.

35
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Re: May Weather Discussion- A Wet Start?

Post by wxdata » Fri Apr 30, 2010 12:24 am

SPC has included SE TX in a sight risk for severe weather Saturday

"A MORE FOCUSED SEVERE WEATHER THREAT IS EXPECTED TO DEVELOP SATURDAY
AFTERNOON FROM ERN TX EWD INTO THE LOWER MS VALLEY AS THE MODERATELY
UNSTABLE ENVIRONMENT COMES UNDER THE INCREASING INFLUENCE OF SHORT
WAVE TROUGH LIFTING NEWD THROUGH THE SRN PLAINS. AS MENTIONED IN
THE SYNOPSIS...THE LOW-LEVEL MASS RESPONSE TO THIS IMPULSE WILL
RESULT IN THE DEVELOPMENT OF A CYCLOGENETIC SURFACE LOW OVER THE
ARKLATEX...AS WELL AS THE REFORMATION OF A 40-50 KT LLJ OVER THE
LOWER MS VALLEY. "

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Re: May Weather Discussion- A Wet Start?

Post by srainhoutx » Fri Apr 30, 2010 11:54 am

Interesting snip from the Updated SPC Outlook for tomorrow...

...EAST TEXAS INTO THE LOWER MISSISSIPPI VALLEY...
INHIBITION SOUTH OF STALLING BOUNDARIES IS BECOMING MORE OF A
CONCERN. BUT THERMODYNAMIC PROFILES...INCLUDING A VERY MOIST
BOUNDARY LAYER WITH 70S DEW POINTS...IN THE PRESENCE OF CONTINUING
STRONG DEEP LAYER AND LOW-LEVEL SHEAR...WILL CERTAINLY SUPPORT
POTENTIAL FOR SEVERE STORMS. MODELS ARE SUGGESTIVE THAT EARLY DAY
THROUGH LATE AFTERNOON AND EVENING STORMS COULD INITIATE IN DISCRETE
FASHION SOUTH OF SURFACE FRONT AND CONVECTIVE OUTFLOW BOUNDARIES.
HOWEVER...STORM MOTIONS WILL TEND TO BE NORTHEASTWARD INTO
POTENTIALLY RAIN-COOLED BOUNDARY LAYER AIR. SO...TORNADIC POTENTIAL
ACROSS EAST TEXAS/LOUISIANA AND MISSISSIPPI INTO ARKANSAS IS STILL
UNCLEAR...THOUGH ENVIRONMENTAL PROFILES MAY OTHERWISE BE FAVORABLE
FOR POTENTIALLY STRONG TORNADOES. LATE IN THE EVENING THROUGH THE
OVERNIGHT HOURS...THE TENDENCY FOR STORM CONSOLIDATION ALONG/NORTH
OF STALLED FRONT AND OUTFLOW BOUNDARIES IS EXPECTED...WITH AT LEAST
A CONTINUING RISK FOR LARGE HAIL/DAMAGING WIND GUSTS.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Re: May Weather Discussion

Post by wxdata » Sat May 01, 2010 1:05 am

SPC must feel the cap holds over SE TX- once again moves slight risk further northward for Saturday.

http://www.spc.noaa.gov/products/outlook/day1otlk.html

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Re: May Weather Discussion

Post by wxdata » Sat May 01, 2010 1:15 am

2am- Golf ball size hail reported near Del Rio.

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