an historical analysis of transient rain bearing systems in the name domain: the impact of inverted...
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An Historical Analysis of An Historical Analysis of Transient Rain Bearing Transient Rain Bearing Systems in the NAME Systems in the NAME Domain:Domain:The Impact of Inverted The Impact of Inverted
Troughs on Monsoon Rainfall Troughs on Monsoon Rainfall
Art Douglas and Phil EnglehartArt Douglas and Phil Englehart
Creighton Creighton UniversityUniversity
Research ObjectivesResearch Objectives
1. To develop an historical climatology of 1. To develop an historical climatology of transient synoptic systems in northern Mexico.transient synoptic systems in northern Mexico.
2. To determine relationships between these 2. To determine relationships between these transient systems and fluctuations in summer transient systems and fluctuations in summer rainfall.rainfall.
3. To relate variability in the frequency of 3. To relate variability in the frequency of transient systems to large scale oceanic and transient systems to large scale oceanic and atmospheric anomalies.atmospheric anomalies.
4. To provide a benchmark for modeling 4. To provide a benchmark for modeling studies in order to determine model studies in order to determine model performance relative to the prediction of these performance relative to the prediction of these transient features and their associated rainfall.transient features and their associated rainfall.
Transient Synoptic Features Transient Synoptic Features Affecting Northern MexicoAffecting Northern Mexico
1. Tropical Cyclones (Published).1. Tropical Cyclones (Published). 2. Inverted Troughs: Cold and 2. Inverted Troughs: Cold and
Warm.Warm. 3. Cold Fronts.3. Cold Fronts. 4. Cutoff Lows.4. Cutoff Lows. 5. Open Troughs.5. Open Troughs.
2222
222
2
2
2
33
3333
3
3 3
33
333
4
44
4 4
4
44
44
44 6
6
6
6
6
6
66
6
555
5
555
55
5
55
5
77
77
777
777
7
11
1
1 111 11 1
1
Data availability: 1950-2001
LO N G -T ER M ST AT I O N S SEVEN SY N O P T I C R EG I O N S
D A I L Y R A I N F A L L C L I M A T O L O G Y ( 1 9 6 1 - 9 0 )( J u n e 1 - S e p te m b e r 3 0 )
C L A S S I C M O N S O O N
N O R T H E A S T & I N T E R I O R
DA
ILY
AV
G.
RA
INFA
LL (
mm
) D
AIL
Y A
VG
. R
AIN
FALL
(m
m)
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
10
0
1
2
3
4
5
6
7
8
9
10
S I N A L O A
S I N A L O A - S O N O R A
S O N O R A
S O U T H E A S T A R I Z O N A
T A M A U L I P A S
D U R A N G O
C H I H U A H U A
J U J L A U S
J U J L A U S
T R O P IC A L C Y C L O N E T O T O T A L S E A S O N A LR A IN F A L L (M E D IA N P E R C E N T A G E )
3
10
76
3
222
60 6
640
20
533
0 1 2
0 2
0 2
4 7
3
8
3 46
8 10
910
10
1439
9 830
168
172112
6 7
8
3 4
58
24
38
T C R A I N F A L L ( m m ) v s . L A N I Ñ Ab y A M O P H A S E
4 1 4 8
3 5 5 1
1 1 2 1 0 85 5
5 9
1 2 4 4 6
1 4 5 1 0 1
1 3 4 1 6 8
1 1 5 1 5 6
2 0 1 1 4 4
2 4 7 3 4
P O S I T I V E A M O N E G A T I V E A M O
1 6 8 9 6
2 0 5 8 66 8
3 3
2 2 7 7 0
1 5 1 8
2 0 1 1 0 7
2 1 7 1 5 3
2 0 7 1 1 2
4 2 3 6
1 2 5 7 7
4 2 8 6
1 2 5 4 3 1 1 7
1 7 1
1 1 8 1 8 2
1 2 4 1 0 7
9 5 1 5 3
1 5 2 9 8
2 0 9 1 2 52 0
2 3
1 5 1 3
1 8 2 7
2 8 3 3
1 8 2 6
8 4 4 2
6 6 5 3
6 0 7 7
5 1 6 9
1 1 11 2 9. 4 1 7 5
9 1
Transient Synoptic Features Transient Synoptic Features Affecting Northern MexicoAffecting Northern Mexico
1. Tropical Cyclones (Published).1. Tropical Cyclones (Published). 2. Inverted Troughs: Cold and 2. Inverted Troughs: Cold and
Warm.Warm. 3. Cold Fronts.3. Cold Fronts. 4. Cutoff Lows.4. Cutoff Lows. 5. Open Troughs.5. Open Troughs.
RAOB Sites
NOAA NWS LIBRARYNOAA NWS LIBRARY
Meridional Wind Time Section8 July to 12 August 2005
Meridional Wind Time SectionJuly 1973
N u m b er o f I n ve rted T ro u g h - D ays o ve r th e N A M D o m a in 1 9 6 7 - 2 0 0 1
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
8
16
24
32
40
48
56
64
72
80
Day s
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
8
16
24
32
40
48
56
64
72
80
Day s
C o m p a r is o n o f N u m b e r o f S y n o p t ic F e a tu r e so v e r th e N A M D o m a in
C L I M O v s 2 0 0 4
F R O N T S I N V E R T E D T R O U G H S
C U T - O F F L O W S
O P E N T R O U G H S
10
20
30
40
50
60
No . of Day
s
3 . 52 . 1
4 . 43 . 5
6 . 33 . 9
6 . 24 . 2
5 . 23 . 0
3 . 51 . 7 5 . 2
2 . 4
167
125
161
148
173
208216
Average Daily Rainfall (mm)
Inverted Trough Days
vs.
Days with No Synoptic Feature
Increase in Daily Rainfall (%)
Inverted Trough Days
with respect to
Days with No Synoptic Feature
51.922.3
72.315.7
121.020.5
137.921.7
116.225.6
93.127.4 101.1
19.9
Inverted Troughs Contribution to Seasonal (June-Sept) Rainfall (1967-2001)
Average Rainfall (mm) Percent Contribution to Seasonal Total
-4-3-2-11 2 3 4
0
1
2
3
4
5
6
7
8
9
-4-3-2-11 2 3 4
0
1
2
3
4
5
6
7
8
9
-4-3-2-11 2 3 4
0
1
2
3
4
5
6
7
8
9
RAINFALL Associated with INVERTED TROUGHS as a function of TROUGH POSITION (i.e. Displacement East (-) or West (+) of the Division Location in º Long.) SONORA/SINALOA DURANGO TAMAULIPAS/NUEVO LEON
16.722.3
25.615.7
11.820.5
16.521.7
20.625.6
23.627.4 8.9
19.9
CONTRIBUTION OF INVERTED TROUGHS TO SEASONAL TOTAL RAINFALL
2004/CLIMO
0 14 28 42 56 70 84 98 112 126
0
2
4
6
8
10
12
14
16
18
Rai
nfal
l (m
m)
0 14 28 42 56 70 84 98 112 126
0
2
4
6
8
10
12
14
16
18
Rai
nfal
l (m
m)
C L I M O
2 0 0 4
SONORA DAI LY RAI NFALL (mm) 2 0 0 4 vs C L I M O (11-pt Binomial Smoothing)
J U N E 1 = 1
Transient Synoptic Features Transient Synoptic Features Affecting Northern MexicoAffecting Northern Mexico
1. Tropical Cyclones (Published).1. Tropical Cyclones (Published). 2. Inverted Troughs: Cold and 2. Inverted Troughs: Cold and
Warm.Warm. 3. Cold Fronts.3. Cold Fronts. 4. Cutoff Lows.4. Cutoff Lows. 5. Open Troughs.5. Open Troughs.
N u m ber o f F ro n ta l D ays o ver th e N A M D o m ain 1 9 6 7 - 2 0 0 1
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
6
12
18
24
30
36
42
48
54
60
D ay s
VIS 16Z October 7, 2005VIS 16Z October 7, 2005
Total Rainfall October 2-7, 2005Total Rainfall October 2-7, 2005
C o m p a r is o n o f N u m b e r o f S y n o p t ic F e a tu r e so v e r th e N A M D o m a in
C L I M O v s 2 0 0 4
F R O N T S I N V E R T E D T R O U G H S
C U T - O F F L O W S
O P E N T R O U G H S
10
20
30
40
50
60
No . of Day
s
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
% s
easo
n al t
o ta l
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
% s
easo
n al t
o ta l
2 0 0 4 = 5 .6 C L IM O = 5 .9
TAMAULIPAS/NUEVO LEON (DIVISION 7)
Percentage of Total Seasonal Rainfall Associated with Fronts (< 350 km)
C o m p a r is o n o f N u m b e r o f S y n o p t ic F e a tu r e so v e r th e N A M D o m a in
C L I M O v s 2 0 0 4
F R O N T S I N V E R T E D T R O U G H S
C U T - O F F L O W S
O P E N T R O U G H S
10
20
30
40
50
60
No . of Day
s
N u m b e r o f C u tO ff L o w - D a ys o ve r th e N A M D o m a in 1 9 6 7 - 2 0 0 1
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
60
Days
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
60
Days
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
60
Days
N u m b e r o f O p e n T r o u g h - D a y s o v e r th e N A M D o m a in 1 9 6 7 - 2 0 0 1
1965 1970 1975 1980 1985 1990 1995 2000 2005
0
10
20
30
40
50
Days
Summary and Conclusions
1. A 35 year climatology of transient synoptic features indicates that NAME 2004 was characterized by:
a. Cold Front Days 200% of normal. b. Inverted Trough Days 70% of normal. c. Cutoff Low Days 90% of normal. d. Open Trough Days 170% of normal.
2. Inverted troughs provide 20%-25% of the summer rainfall received in NC and NE Mexico.
3. Rainfall with IV troughs peaks when the system is overhead in NC Mexico. Rainfall peaks in Western Mexico when the IV system is 3° to 4° upstream: associated with MCS development ahead of IV troughs (downslope, weak capping).
4. IV Rainfall in NE Mexico peaks when the system is 4° upstream and this may be related to disruption of the normal divergent trade system in the western Gulf of Mexico
5. In NE Mexico cold fronts provide about 6% of the normal summer rainfall (June to September).