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**Point Forecast Matrices**

#  PFM User's Guide

The PFM displays forecast weather parameters in 3, 6, and 12 hour
intervals out to 7 days in the future. To see what the different values
mean, refer to the associated red numbers on the pages below.

FOUS51 KRAH 161733 (1)

PFMRAH

POINT FORECAST MATRICES (2)

NATIONAL WEATHER SERVICE RALEIGH, NC

233 PM EDT WED OCT 8 2003

NCZ024-025-041-090633

RALEIGH DURHAM AIRPORT-WAKE, NC(3)

35.8N 78.78W

233 PM EDT WED OCT 8 2003

DATE (4) TUE 09/16/03 WED 09/17/03 THU 09/18/03

UTC 3HRLY 09 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21
00

MDT 3HRLY 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15
18

MAX/MIN(5) 59 36 46 31 60

TEMP (6) 57 59 56 50 43 38 36 39 44 46 44 40 35 32 31 41 55 60 57

DEWPT (7) 39 39 39 38 38 37 36 36 35 35 34 32 30 28 28 29 30 31 31

RH (8) 51 47 53 63 82 96100 89 70 65 68 73 82 85 88 62 38 33 37

WIND DIR (9) NE NE NE N NW NW NW NW NW NW NW NW NW W W W W W W

WIND SPD (10) 10 10 10 11 14 14 14 14 21 21 17 17 17 11 11 10 10 10 10

CLOUDS (11) BK BK OV OV OV OV BK BK BK BK BK BK BK BK SC SC FW FW FW

POP 12HR (12) 60 80 50 30 0

QPF 12HR (13) 0.03 0.21 0.04 0.03 0

SNOW 12HR (14) 00-00 00-00 00-00

RAIN SHWRS(15)

SNOW (15) D D C C C C C C

RAIN (15) L L D D D D C C C C C C

OBVIS (16) F F PF

WIND CHILL(17) 36 29 27 31 36 38 36 31 25 23 22 34

MIN CHILL (18) 37 36 27 27 36 25 22 24

DATE (19) FRI 09/19/03 SAT 09/20/03 SUN 09/21/03 MON 09/22/03

UTC 6HRLY 06 12 18 00 06 12 18 00 06 12 18 00 06 12 18 00

MDT 6HRLY 00 06 12 18 00 06 12 18 00 06 12 18 00 06 12 18

MIN/MAX 40 66 42 62 38 68 40 70

TEMP 46 40 61 63 49 42 59 59 45 38 63 64 48 40 65 66

DEWPT 33 34 40 MM MM MM MM MM MM MM MM MM MM MM MM MM

PWIND DIR (20) W W NW NW NW W W W

WIND CHAR (21) GN GN BZ BZ GN GN BZ GN

AVG CLOUDS (22) SC BK BK BK BK BK BK BK BK FW FW FW FW FW FW

POP 12HR 0 0 0 30 30 0 0 0

RAIN SHWRS C C C C

\$\$

\(1\) - This is the WMO Identification Code for the product, the issuing
office identifier and the issuance date and time in UTC.

\(2\) - This is the product name, issuing office information, and data
and time of product issuance in local time.

\(3\) - This is the area or point location the forecast is for, and the
date and time in UTC that the forecast product expires.

\(4\) - Forecast Date and Time group. The forecast times and dates are
listed, both in UTC and in local time, with 3 hour increments for most
products.

\(5\) -MAX/MIN: - (Alternatively labeled as MIN/MAX for afternoon
issuance) A forecast of maximum or minimum temperatures in degrees
Fahrenheit (F). The nighttime MIN and daytime MAX may be displayed as
single integer (e.g., -2, 8, 53, 102) as a range (e.g., 54 56 60) if the
MAX/MIN temperatures are expected to vary across the area. In area
forecasts, the middle number within the range is the representative
single digit value for that area. MAX/MIN is forecast out through Day 7.

\(6\) - TEMP: The expected temperature in degrees F valid at the
indicated hour. The temperature is right justified in the column below
the hour to which it refers. TEMP is forecast at 3-hour intervals
through 60 hours, then 6-hour intervals through Day 7.

\(7\) - DEWPT: The expected dew point temperature in degrees F for the
same time periods as its corresponding temperature forecast. DEWPT is
located directly below the temperature line.

\(8\) - RH: The relative humidity (RH) is the expected RH for the same
time periods as its corresponding temperature and dew point forecast.
The RH row is located directly below the "DEWPT" row. RH is available at
3-hour increments through 60 hours.

\(9\) - WIND DIR : A snapshot of the expected forecast direction that
the wind is coming from at the indicated hour, using the 8 points of a
compass (i.e., N, NE, E, SE, S, SW, W, NW). If a calm wind is forecast,
double zeros (00) will be listed in place of a wind direction. WIND DIR
is located below the hour to which it refers. WIND DIR is available in
3-hour increments out to 60 hours.

\(10\) WIND SPD and WIND GUST A snapshot of the sustained wind speed in
miles per hour (MPH) forecast to occur at the indicated hour. If a calm
wind is forecast, double zeros (00) will be listed in place of a wind
speed. WIND SPD is valid in 3-hour increments out to 60 hours. A wind
gust row will appear in the 3HRLY block whenever forecasted wind gusts
exceed the sustained wind speed (WIND SPD) by at least 10 MPH.

\(11\) CLOUDS: The amount of sky coverage during the indicated hour.
CLOUDS is divided into five category codes ranging from clear to
overcast . Each code represents an equivalent percentage of sky cover in
percent. CLOUDS parameter is included in 3-hour time intervals out to 60
hours. (See Table)

\(12\) POP 12HR: Probability of Precipitation (POP), is defined as the
likelihood, expressed as a percent, of a measurable precipitation event
(.01 of an inch) at any given point within the forecast area(s) covered
by the PFM. The "12HR" refers to the 12-hour valid time ending at 6:00
a.m. or 6:00 p.m. local time (0600 or 1800).

\(13\) QPF 12HR: This parameter, quantitative precipitation forecast
(QPF) represents the total amount of liquid precipitation, in inches,
expected during a 12-hour period ending at 6:00 a.m., or 6:00 p.m. local
time at any point in the forecast area.

\(14\) SNOW 12HR: The expected range of total snowfall accumulation (in
whole inches) forecast to occur at the specific point during a 12-hour
period ending at 6:00 a.m. or 6:00 p.m. local time. SNOW 12HR will only
appear during the locally defined winter period. The snow parameter
contains 1 to 5 alphanumeric characters which are right justified in the
column below the hour defining the ending time of the precipitation
period. SNOW 12HR may appear as a one or two digit number (1, 4, 12), or
as a specified range (2-4, 8-12). When no snowfall is forecast during
the locally specified winter period, double zeros (00-00) will appear in
the row. Snowfall that is not measurable (less than 0.1 inch of frozen
precipitation) is referred to as a trace. A trace of snow is depicted by
a "T." SNOW 12HR is forecast out to 36 hours.

\(15\) PRECIPITATION TYPE AND CATEGORY: The PFM may list several types
of precipitation. Precipitation types only appear in the PFM if they are
forecast to occur at any point within the zones(s) during the seven day
forecast. (See Table)

\(16\) OBVIS: If an obstruction to visibility (OBVIS) is forecast for
the zone, a row labeled OBVIS will be listed underneath any forecast of
precipitation. If no precipitation is forecast, then OBVIS will be
listed under the row labeled AVG CLOUDS. In the Figure 19 example, "K"
implies that smoke is restricting visibility during the 6-hour period
from 3:00 a.m. - 9:00 a.m. EST on Monday 2/12/01. OBVIS is forecast at
3-hour intervals through 60 hours. (See Table)

\(17\) WIND CHILL: Wind Chill is included seasonally based upon locally
defined criteria. The decision on whether to include or exclude these
parameters is determined by the local WFO criteria. The Wind Chill is
forecast out to 60 hours.

\(18\) MIN CHILL 6HR: When WIND CHILL values appear in the PFM, a 6-hour
minimum wind chill may appear on the following row. These values
indicate the minimum wind chill index forecast to occur during the
6-hour period ending at the time indicated at the top of the column. MIN
CHILL 6HR is forecast out to 60 hours.

\(19\) Forecast Date and Time group for the extended forecast periods
from 60 hours through Day 7. The data is generally in a 6 hourly
increment.

\(20\) In the 6HRLY block, PWIND DIR is the "predominant" wind direction
for the zone(s) during the 12-hour period between 6:00 a.m. and 6:00
p.m., or 6:00 p.m. and 6:00 a.m. local time. PWIND DIR is valid beyond
60 hours through Day 7.

\(21\) WIND CHAR: Used beyond 60 hours through Day 7 of the forecast and
denote the character of the wind for the 12-hour period between 6:00
a.m. and 6:00 p.m., or 6:00 p.m. and 6:00 a.m. WIND CHAR is comprised of
range categories used in conjunction with deterministic wind speeds.
Each range category is equated to a descriptive wind term, i.e., a "wind
character" to best describe the MAXIMUM SUSTAINED wind speed during the
12 hour period.

\(22\) AVG CLOUDS: Valid for 6-hour increments beyond 60 hours through
Day 7 and indicates the average amount of all clouds during the 6-hour
period ending on the hour indicated at the top of the column.

+-------------------------+--------------------+-----------------------+
| Wind Speed              | Precipitation Type | Obstructions to       |
| Characteristics Table   |                    | Visibility            |
|                         | RAIN Rain          |                       |
| LT Light \< 8 mph       |                    | F Fog                 |
|                         | RAIN SHWRS Rain    |                       |
| GN Gentle 8 - 14 mph    | Showers            | PF Patchy Fog         |
|                         |                    |                       |
| BZ Breezy 15 - 22 mph   | SPRINKLES          | F+ Dense Fog          |
|                         | Sprinkles          |                       |
| WY Windy 23 - 30 mph    |                    | PF+ Patchy Dense Fog  |
|                         | TSTMS              |                       |
| VW Very Windy 31 - 39   | Thunderstorms      | H Haze                |
| mph                     |                    |                       |
|                         | DRIZZLE Drizzle    | BS Blowing Snow       |
| SD Strong/Damaging = 40 |                    |                       |
| mph                     | SNOW Snow          | K Smoke               |
|                         |                    |                       |
|                         | SNOWSHWRS Snow     | BD Blowing Dust       |
|                         | Showers            |                       |
|                         |                    | VA Volcanic Ash       |
|                         | FLURRIES Snow      |                       |
|                         | Flurries           |                       |
|                         |                    |                       |
|                         | SLEET Ice Pellets  |                       |
|                         |                    |                       |
|                         | FRZNG RAIN         |                       |
|                         | Freezing Rain      |                       |
|                         |                    |                       |
|                         | FRZNG DRZL         |                       |
|                         | Freezing Drizzle   |                       |
+-------------------------+--------------------+-----------------------+
| Clouds/Sky Cover        | POP Codes          | POP Codes Convective  |
|                         | Stratiform or      | Only                  |
| CL Clear/Sunny 0%= 6%   | Convective         |                       |
|                         |                    | IS Isolated (= 20%)   |
| FW Mostly Clear/Mostly  | S Slight Chance (= |                       |
| Sunny \> 6% and = 31%   | 20%)               | SC Scattered          |
|                         |                    | (30%-50%)             |
| SC Partly Cloudy/Partly | C Chance (30%-50%) |                       |
| Sunny \>31% and = 69%   |                    | NM Numerous (60%-70%) |
|                         | L Likely (60%-70%) |                       |
| BK Mostly Cloudy \>69%  |                    | EX None (80%-100%)    |
| and = 94%               | O                  |                       |
|                         | Occasional/Periods |                       |
| OV Cloudy \>94% and =   | of (80%-100%)      |                       |
| 100%                    |                    |                       |
|                         | D None (80%-100%)  |                       |
+-------------------------+--------------------+-----------------------+