FOBX51 EBWM 232100
SYNOPTIC BULLETIN VALID FROM :
24/07/2007 00.00Z TILL 28/07/2007 00.00Z
AREA : BELGIUM
ON DUTY : DJ
1. MODEL OUTPUT ASSESSMENT
==========================
FORECAST BASED ON THE SHORT-RANGE OUTPUT OF HIRLAM AND THE
GFS-RUN 23/12Z.
GFS-EPS SHOWS A LARGE RELIABILITY IN THE FORECAST AS THE
OPER IS WELL PLACED IN THE TUBE. THIS IS ALSO THE CASE ON
MEDIUM RANGE. SOME SPREADING FROM SUNDAY ON, BUT THEN AGAIN
THE OPER IS PERFECTLY IN BALANCE WITH THE DIFFERENT
MEMBERS.
2. SYNOPTIC SITUATION EVOLUTION UP TO D+4
=========================================
2.1 SHORT SUMMARY
-----------------
TODAY WILL BE UNSETTLED WITH A GRADU STABILISATION IN THE
EVENING. WEDNESDAY WILL TURN OUT RATHER SWELL AND WARM WITH
NICE SUNNY PERIODS ENDING IN CLOUDY WX OVER THE WEST IN THE
EVENING. THURSDAY AND PARTIALLY FRIDAY AGAIN UNSETTLED.
SATURDAY TEMPO ZONAL FLOW WITH TAILS OF FRONTS PRODUCING
LGT RAIN OR RAINSHOWERS. SUNDAY TEMPO A SUNNY AND WARM DAY.
2.2 DAILY EVOLUTION
-------------------
TODAY:
AN UPPER TROUGH OVER THE NORTHSEA AND OUR COUNTRY INTO
FRANCE HAS BEEN FED WITH A NEW POOL OF COLD AIR IN THE PAST
FEW DAYS. THE ASSOCIATED JETSTREAK IS MOVING UP THE UPWARD
BRANCH AND CREATED A DEEPENING DEPRESSION IN THE LEFT EXIT.
THE SURFACE DEPESSION IS SITUATED OVER HOLLAND IN THE
BEGINNING OF THE SEQUENCE, AND MOVES SLOWLY NE TO BE
POSITIONED OVER DENMARK AROUND 12Z AND NEAR THE BALTIC SEA
THIS EVENING. PRESSURE GRADIENT ON THE SW'ERN FLANK IS
QUITE TIGHT AND WINDS WILL TEMPO TURN OUT TO BE RATHER
STRONG. THE UPPER TROUGH STARTS TO RELAX AND THE JET LOOSES
IDENTITY AND SO, THE DEPRESSION WILL SLOWLY FILL WHILE
PRESSURE GRADIENT EASES. ASSOCIATED WAVING COLD FRONT IS
LINGERING OVER GERMANY/POLAND AND THE ALPS, WHILE AN ACTIVE
TROUGHLINE IS GLIDING UNDERNEATH THE LOWLANDS INTO GERMANY.
HOWEVER, AN IMPORTANT BACKBENT-OCCLUSION WILL CROSS THE
AREA FROM WEST TO EAST IN THE FORENOON/NOON TO LEAVE THE
COUNTRY IN EARLY AFTERNOON. INSTABILITY INDICES YET AGAIN
INDICATE A SLIGHT THREAT OF THUN EMB IN THIS SYSTEM.
ACCUMULATION OF PCIP! THIS FEATURE WILL BE FOLLOWED BY AN
ILL DEFINED OCCLUSION (ORIGINALLY ASSOCIATED TO THE
DEPRESSION OVER SCANDINAVIA) THAT WILL FOLLOW THE SAME
TRACK IN THE AFTERNOON. THIS LATTER WILL BE SLIGHTLY LESS
ACTIVE AND SUBJECT TO DAILY EVOLUTIONS AS PROG-TEMPS
INDICATE THE CUSC-CLOUDS TO BE TOPPED AROUND FL100 ISOL
140. THIS IS THE RESULT OF THE WAA SETTING IN, AND FINALLY
THE APPROACH OF A RIDGE OF HIGH PRESSURE THIS EVENING FROM
THE WEST. T850HPA AROUND P08°C TEMPO LOWERING TO CA. P06°C
AROUND NOON.
OVERNIGHT:
OUR WX IS INFLUENCED BY THE RIDGE OF HIGH PRESSURE
EXTENDING FROM THE ACORES INTO THE UK, MOVING EAST. T850HPA
GENTLY RISING TO P08°C.
WEDNESDAY:
AT FIRST STILL INFLUENCE OF THE UPPER RIDGE OVERHEAD.
OVER THE ATLANTIC, A NEW PLUNGE OF COLD AIR IS DIGGING SE.
ASSOCIATED UPPER TROUGH SLOWLY STARTS TO RELAX WITH THE JET
POSITIONING IN THE SE'ERN FLANK. AS A RESULT, THE ASSO
FRONTAL SYSTEM WILL APPROACH FROM THE WEST WHILE WAVE-
FORMATION IS ENGAGED IN THE COLD FRONT. THE TAIL OF THE
WARM FRONT WILL GLIDE OVER THE WEST OF THE COUNTRY IN THE
AFTERNOON, INITIALLY ONLY PRODUCING A GATHERING OF MEDIUM
AND HIGH CLOUDS. IN THE COURSE OF LATE AFTERNOON, ALSO
LOWER CLOUDS WILL BECOME IMPORTANT, ESP OVER THE EXTREME W
AND NW, WITH A RISK OF SOME LGT PCIP. T850HPA BECMG P10-
P11°C IN THE TINY WARM SECTOR.
OVERNIGHT:
THE UPPER RIDGE IS FURTHER RETREATING EAST AND THE WAVING
COLD FRONT IS SLOWLY ENTERING THE COUNTRY IN THE
EVENING/SECOND PART OF THE NIGHT AND MAKING ITS WAY EAST.
T850HPA DOWN TO P09°C.
THURSDAY:
THE RELAXING UPPER TROUGH OVER THE UK IS SWINGING EAST
GRADU PUSHING THE NOCTURNAL FRONTAL SYSTEM TO THE EAST.
MARITIME AND UNSTABLE AIR WILL BE ADVECTED AS THE FLOW
REMAINS WELL CYCLONIC AT ALL LEVELS. INSTABILITY WILL
PARTLY BE DEPENDING ON DAILY EVOLUTIONS.
THE REMNANTS OF THE WRAPPED AROUND OCCLUSION (AROUND THE
DEPRESSION OVER SCOTLAND) WILL REORGANISE AND BE ADVECTED
TOWARDS THE COUNTRY. THIS FRONTAL SYSTEM WILL APPROACH FROM
THE WEST IN AFTERNOON AND EVENING, ENHANCING THE RISK OF
SHOWERS OR SHOWERY RAIN. THE RISK OF A THUN IS EVALUATED TO
BE RATHER SMALL AT THE MOMENT. T850HPA AROUND P08°C.
FRIDAY:
THE FRONTAL SYSTEM WILL LEAVE THE AREA BY MID FORENOON AND
IS RAPIDLY FOLLOWED BY THE STEERING UPPER TROUGH. THIS
LATTER WILL TEMPO KEEP THE RISK OF SHOWERS ALIVE. FROM THE
WEST, A WEAK UPPER RIDGE IS MOVING IN AND WILL TEMPER
FURTHER INSTABILITY IN PM. IN THE FOLLOWING NIGHT A SFC-
RIDGE WILL CROSS. SUBSIDENCE WILL GRADU BE THE MOST
IMPORTANT FACTOR. T850HPA AROUND P08°C.
3. WEATHER
==========
3.1 FOR TODAY
--------------
MOSTLY CLOUDY, OVER THE SE AT FIRST CLOUDY, WITH SHOWERY
RAIN OR SHOWERS, MOD AT TIMES, SLOWLY SPREADING FROM WEST
TO EAST. RISK OF AN ISOL EMB THUN. LOC ACCUMULATION OF
PCIP! IN AFTERNOON FROM THE WEST CLOUDY WITH LOC
RAINSHOWERS AND SOME MINOR BREAKS. TMAX P15-P20°C.
RATHER STRONG W TO NW'LY 13-17KT WITH GUSTS 30-35KT, WINDS
BACKING TO SW IN LATE PM BECMG 06-10KT. COT RATHER STRONG
NW'LY 14-20KT GUSTS 35-40KT GRADU BACKING SW IN THE COURSE
OF PM BECMG 10-15KT.
OVERNIGHT:
LOC SHOWERS SOON MOVING INTO GERMANY BECMG FROM WEST PARTLY
CLOUDY AND DRY. MIST FORMATION AROUND DAWN WITH A SLIGHT
RISK OF LOW TURBULENT CLOUDS. TMIN P08-P13°C, COT APPROX
P15°C. MOD SW'LIES 05-10KT, COT 08-12KT.
3.2 FOR TOMORROW
-----------------
AFTER DISSIPATION OF MORNING-MIST AND POSS LOW CLOUDS, AT
FIRST LARGE BREAKS AND SUNNY. FROM LATE FORENOON FROM W,
INCREASING CLOUDINESS (MAINLY MEDIUM AND HIGH OVER CENTRE)
BECMG CLOUDY TO MOSTLY CLOUDY. RISK OF LGT RAIN OVER
EXTREME W AND NW. THE CENTRE AND EAST WILL REMAIN DRY. TMAX
P19-P23°C. MOD SW'LIES 08-12KT, COT MOD TO RATHER STRONG SW
GRADU SSW'LY 10-15KT.
OVERNIGHT:
MAINLY CLOUDY TO MOSTLY CLOUDY AND PERIODS OF LGT RAIN
SLOWLY SPREADING INLAND. TMIN P11-P16°C. WEAK TO MOD SSW'LY
04-08KT, COT MOD 08-13KT.
3.3 FOR THURSDAY JULY 26TH 2007
------------------------------
OVER THE EAST AT FIRST STILL MOSTLY CLOUDY WITH PERIODS OF
LGT RAIN, GRADU IN FORENOON BECMG LIKE REMAINDER: MAINLY
CLOUDY TEMPO PARTLY CLOUDY AND RISK OF RAINSHOWERS
INCREASING WITH DAILY EVOLUTIONS. THE RISK OF SHOWERS
INCREASES EVEN MORE IN THE EVENING FROM THE WEST. TMAX P19-
P23°C.
MOD TO RATHER STRONG SW'LY 08-12KT INLAND AND 13-18KT COT.
RISK OF LOCAL GUST REACHING WARNING LIMITS IN EVENING INVOF
MOD SHOWERS.
OVERNIGHT:
CLOUDY TO MOSTLY CLOUDY AND PERIODS OF RAIN OR RAINSHOWERS,
MOD AT TIMES. TMIN P12-P15°C. MOD COT RATHER STRONG SW'LY
VEERING TO WSW TO W IN THE NIGHT 10-14KT INLAND AND 13-18KT
COT. RISK OF GUSTS 30-35KT.
3.4 FOR FRIDAY JULY 27TH 2007
------------------------------
AT FIRST CLOUDY TO MOSTLY CLOUDY WITH RAINSHOWERS OR
SHOWERY RAIN MOVING TO THE EAST. FROM FORENOON GRADU PARTLY
CLOUDY TO CLOUDY AND RATHER SUNNY/DRY. TMAX P18-P23°C.MOD
TO RATHER STRONG WSW'LY BACKING TO SW IN AFTERNOON AND
EASING. INLAND 10-15KT GRADU 05-10KT, COT 12-18KT GRADU 10-
15KT.
OVERNIGHT:
CLOUDY GRADU MOSTLY CLOUDY IN SECOND PART OF THE NIGHT.
ISOL SOME LGT RAIN. TMIN P09-P15°C. MOD SW GRADU SSW, 05-
10KT INLAND AND 08-12KT COT.
4. OUTLOOK :
==========
4.1 FOR SATURDAY 28TH 2007
------------------------------
A ZONAL FLOW TEMPO INFLUENCES OUR WX, POINTING THE JETAXIS
OVER THE UK TOWARDS THE NETHERLANDS. BELGIUM REMAINS ON THE
WARM SIDE WITH TAILS OF (WARM) FRONTAL SYSTEMS CROSSING THE
AREA. T850HPA GRADU P10°C.
WX: CLOUDY TO MOSTLY CLOUDY. DRY PERIODS ALTERNATE WITH LGT
RAIN OR DRIZZLE OR A LOC SHOWER, ESP OVER THE N'ERN HALF.
TMAX P18-P22°C. TMIN P14-P17°C. MOD SW'LIES, OVER WEST
GRADU MOD TO RATHER STRONG.
4.2 FOR SUNDAY 29TH 2007
------------------------------
ATLANTIC UPPER TROUGH DIGGING SOUTH WITH STRONG WAA ON
FORWARD SIDE, PUSHING THE FRONTAL SYSTEMS SLOWLY TO THE
NORTH. WARMER AND DRY AIR INVADING THE COUNTRY FROM THE SW
TO SSW WITH T850HPA LIFTING TO P13°C. NEXT FRONTAL SYSTEM
ONLY EXPECTED IN FOLLOWING NIGHT.
WX: PARTLY CLOUDY AND SUNNY. WARM. IN PM GRADU CLOUDY BY
HIGH AND LOC MEDIUM CLOUDS. TMAX P24-P28°C. MOD SW GRADU
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