500 hpa and prog charts Flashcards
How long after observation time are the 500 vorticity and 500 thickness charts transmitted?
vorticity - 2 hrs
Thickness - 3.5 hrs
what are the letters or symbols used to indicate a vorticity maxima and a minima?
Maxima - C or +
Minima - A or -
Define Isopleth
Line of equal or constant value of a given quantity
The smaller the quadrilateral, the ______ the advection
greater
when isopleths are parallel to the contour lines, what is the advection value?
0
Define positive vorticity advection
Advection of higher values of vorticity, which is often associated with upward motion of the air.
What does negative vorticty advection represent?
Lower levels of vorticity moving towards higher levels of vorticity
NVA is associated with _______ and PVA is associated with _________
NVA - Convergence
PVA - Divergence
PVA is indicitive of:
Falling pressure, rising motion, and instability
The thickness pattern on the 500hpa chart reflects the :
Mean temperature of the layer between 500hpa and 1000 hpa and is proportional to the mean temperature of the air below 18000ft
Warm thickness advection supports:
Cyclogenesis
Fronts are usually located on the _____ of the thickness field.
warm.
the area between the 534 and 540 dashed lines is stippled to indicate ______ and is colored ______
change of phase state
yellow
The low to mid sfc prog chart (sfc to 400mb) contains:
- Pressure centers, surface fronts
- Surface positions of tropical storms
- significant clouds
- turbulence, freezing lvl, and icing
the comox sfc prog chart is issued for the period of __________
12, 24 and 36 hr
the CMC sig wx prog (400mb to 700mb) is prepared ____ times daily and is transmitted _____ after the GFAs.
4 times
1 hr
The mid level prog contains:
- surface presure centers, tropical storms, frontal positions
- Significant cloud, turbulence, freezing lvl and icing
The forecast wind chart for FL240 contains winds and temps for FL ______ and is produced by:
FL 240, 340 and 450
WAFC in washington, DC
List the steps necessary for interpolating conditions between 2 points on an analyzed weather chart
- Recognize the chart
- Understand the plotting model
- Proportional distance
- Topography/local effects
RUPT
Define local effect
Localized weather caused by the interaction between the atmosphere and the earth’s topography
The significance of localized weather is:
the localized weather doesn’t fit the synoptic picture
what scale is a local effect?
mesoscale
List the significant factors that contribute to the formation of local effects
Moisture
Stability
Circulation
List the local effects that occur near water bodies
Moisture source Streamers Thermal lows Moderated temperature extremes Land/Sea breezes Convergence zones Fog/stratus
List the local effects that occur over higher terrain
Orographic clouds Wind Persistent radiation fog Persistent freezing rain Windshear
List the local effects that occur near cities/industrial areas
Poor visibility
Ice fog
List the steps required to address discrepancies between current and forecast weather, prior to calling the forecast office:
Identify discrepancies
Determine MANAIR requirements
Apply local procedures
What are the shortcuts to pull up upper air plots on FWGS
TA - Temp, t-12 TB - temp, pressure, Td AN - tephigram PB - sig and mandatory winds PA - sig winds only UP - entire upper air plot
