A deterministic post-processing program for an

Automatic Weather Interpretation

Fabrizio Ciciulla

Italian Meteorological Service(UGM / CNMCA)

Contents

• Introduction

• Architecture of AWI program

• Case studies

• Planned developments

IntroductionIntroduction

For an operational forecaster it’s important to rely on automatic technical procedures in the numerical model output fields analysis and interpretation.

Such a guidance tool will describe the numerical model output in a synoptical way and will suggest the possibility of occurence for weather events like fog, drizzle, showers or thunderstorms.

At this end the Italian Air Force Meteorological Service is renewing its post-processing operating procedures realizing such an objective and automatic interpretation of numerical model output fields by means of a program called AWI (Automatic Weather Interpretation).

The original idea for such a program derives from the automatic weather interpretation scheme developed by DWD.

AWI Post-Processing of LM fields DWD

Architecture Architecture of the AWI programof the AWI program

Design choices

– Use of standard format for I/O (in order to let a possible exchange of the product)

» GRIB (input) (LAMI, italian version od LM, produced by CINECA with BC from GME)

» BUFR (output) (as a forecast pseudo-synops dataset)

– Use of a scheme adapted to WMO regulations– Weather phenomena distinguished :

» Fog (with and without rime ice)» Drizzle (also freezing)» Rain-fall (slight, moderate, heavy / freezing)» Snow-fall (slight, moderate, heavy)» Snow-showers (slight, moderate to heavy, violent)» Rain-showers (slight, moderate to heavy, violent)» Thunderstorm and heavy thunderstorm

GRIB (DATASET)

DECOD

AWI BUFR(DATASET)

ENCOD

Plottingroutines

maps

GRIBreading

I

ARRAYloading

Calculation of thePRECIP RATE

ARRAYSCANNING

ELAB

GRID-POINTFUNCTION

WWARRAY

O

CONTROLOUTPUT

FILE

BUFR

AWI

WW

FOG DZ RA SNSHRA SHSN TS

Grid-point Function

10 mtwindspeed

T (2 mt)

K RAIN(mm/h)

LS RAIN(mm/h)

Td(2 mt)

K SNOW(mm/h)

LS SNOW(mm/h)

CLDscoverage

C-LWCRH

SurfaceP

T (ml) P (ml) OROG LSM T (pl)

Top of the CC

Base of theCC

SoilT

Input Data

FOG

Conditions

A Total precipitation < an assigned threshold ( 0.015 mm/h )

C Height < 300 mt

B T2m – TD2m < ΔT (it depends on the Tsoil value)

D 10m windspeed < a max assigned threshold

E 10m windspeed > a min assigned threshold

F T2m OR Tsoil < -1 °C

Phenomena

WW = 451 {

A B C Dand

and

and

} IF

2 {

E Fand

and

} IF 1

=

= WW = 48

SNOW - 1Conditions

A Total precipitation > an assigned threshold ( 0.015 mm/h )

B ( LS precipitation > Convective precipitation ) OR (MC coverage > 95 %)

E T2m < a min assigned threshold (-10 °C)

F Supplementary Condition for liquid Preciopitation not verified

C T2m < a max assigned threshold (1 °C)

D IF Solid Precip > 0

D1 (LP > 0) and (0.25 LP <= SP < 0.75 LP)

D2 ((LP > 0) and (SP >= 0.75 LP)) or (LP = 0)

D3 (LP > 0) and (SP < 0.25 LP)

G Precipitation-rate threshold G1 ( TP <= 0.25 mm/h )

G2

G3

G4

( TP > 0.25 mm/h ) and ( TP <= 2 mm/h )

( TP > 2 mm/h )

( TP <= 2 mm/h )

SNOW - 2

Phenomena

{

}

A B Cand

and

1 = and ( NOT ) D3Condition

{{

D1 Fand ( or ) } IF 1WW = 68G4 IF

WW = 69ELSE

G3IF

WW = 73

WW = 70

WW = 75

and ( or or ) {

D2 E }

IF 1 F {G1IF

G2IF

THUNDERSTORM

Conditions

A Total precipitation > an assigned threshold ( 0.2 mm/h )

C TTI > 40

B Pbase_CC – Ptop_CC > 400 hPa

Phenomena

{

A B Cand

and

} IF

WW = 95{

IFCP > 0.5 mm/h

- 4 <= KOI < 2

WW = 96{

IFCP > 2 mm/h

KOI < - 4

Case StudiesCase Studies

Case 1Case 1

11 – 12 March 200311 – 12 March 2003

LIMS 120655Z 22002KT 2800 BR NSC 06/05 Q1021 RMK BKN FEW120 BKN200 YLO

LIMN 120655Z 01001KT 0500 FG NSC 03/02 Q1020 RMK FEW FEW200 RED

LIMC 120650Z 00000KT 0900 R35R/1500N R35L/1500N BCFG RED

LIME 120650Z VRB01KT 1500 BR SCT015 BKN020 09/07 Q1021

LIPL 120655Z 29009KT 2800 BR FEW040 SCT200 11/09 Q1021 RMK BKN YLO

LIPX 120655Z 03001KT 0800 R05/P1500 FG FEW005 SCT100 06/05 Q1021 RMK BKN AMB

LIPT 120655Z 00000KT 0000 FG VV001 06/05 Q1021 RMK RED

LIPS 120655Z 07003KT 0000 FG VV001 07/06 Q1021 RMK RED

LIPH 120655Z 09002KT 0050 R07/0175 FG VV001 08/07 Q1021 RMK WIND THR07 09002KT RED

LIPZ 120650Z 00000KT 0100 R04/0250N FG VV001 08/07 Q1020

LIPI 120655Z 02002KT 1500 BR SCT030 SCT070 08/07 Q1021 RMK BKN AMB

METAR of 12 - 03 - 2003, 07.00 UTC