Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 281935
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
235 PM CDT MON JUL 28 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 235 PM CDT MON JUL 28 2014

FAIRLY QUIET WEATHER THIS WEEK. SCATTERED SHOWERS...MAINLY DURING
THE AFTERNOONS AND EVENINGS...WITH SEASONABLE TEMPERATURES.

HIGHLY AMPLIFIED PATTERN NOW IN PLACE ACRS NOAM...WITH SEASONABLY
DEEP UPR TROFS OFF THE BRITISH COLUMBIA COAST AND OVER ERN NOAM...
BRACKETING A STG UPR RIDGE OVER THE INTERMOUNTAIN WEST. THE UPR
PATTERN IS VERY STABLE...AND LITTLE CHG TO THE TROF AND RIDGE
POSNS IS EXPECTED DURING THE PERIOD. BUT A GRADUAL MODIFICATION
OF THE COLD AIR IN THE ERN NOAM UPR TROF WL CAUSE THE FLOW ACRS
THE ERN CONUS TO GRADUALLY WEAKEN.

THE NW UPR FLOW REGIME WILL KEEP TEMPS A LITTLE BELOW NORMAL
EARLY IN THE FCST PERIOD...WITH READINGS MODERATING TO NR OR A
LITTLE ABV NORMAL BY THE WEEKEND. THERE WILL BE AMPLE
OPPORTUNITIES FOR PRECIPITATION AS DISTURBANCES RIDE SEWD ACRS
THE AREA. BUT THE MAIN POOL OF VERY MOIST UNSTABLE AIR WL REMAIN
WELL TO OUR S...AND WITH MOISTURE LIMITED...PCPN AMNTS WL BE
MODEST.
&&

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 235 PM CDT MON JUL 28 2014

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW AN UPPER
RIDGE CENTERED OVER THE WESTERN NOAM AND TROUGH AXIS RUNNING FROM
EASTERN QUEBEC SOUTHWARD OVER THE EASTERN GREAT LAKES AND
APPALACHIANS.  BETWEEN THESE TWO FEATURES...A BROKEN CU FIELD POPPED
UP AGAIN AROUND MIDDAY.  THERE IS A SHORTWAVE DROPPING SOUTH JUST
NORTH OF LAKE SUPERIOR THAT IS PRODUCING SCATTERED SHOWERS OR
SPRINKLES.  AS THIS WAVE DROPS INTO THE AREA...SMALL SHOWER CHANCES
TONIGHT...AND THUNDER CHANCES TOMORROW ARE THE MAIN FORECAST
CONCERNS.

TONIGHT...THE WEAK SHORTWAVE JUST NORTH OF LAKE SUPERIOR WILL
CONTINUE TO MOVE SOUTHEAST ACROSS THE UPPER PENINSULA AND DOOR
COUNTY.  SCATTERED TO BROKEN MID-LEVEL CLOUDS WILL ACCOMPANY THE
SHORTWAVE WHICH WILL SPREAD ACROSS MUCH OF THE FORECAST AREA THIS
EVENING.  BECAUSE OF A FEW RETURNS SHOWING UP ON CANADIAN
RADARS...WILL ADD A CHANCE OF SPRINKLES OVER NORTH-CENTRAL WISCONSIN
FOR MUCH OF THE NIGHT.  LOW LEVEL TEMPS DO NOT WARM MUCH
TONIGHT...BUT A RELATIVELY TIGHT PRESSURE GRADIENT AND MORE CLOUD
COVER SHOULD LEAD TO A SLIGHTLY WARMER NIGHT THAN YESTERDAY.  WENT
WITH LOWS RANGING FROM THE UPPER 40S NORTH TO MIDDLE 50S SOUTH.

TUESDAY...THE DEEP UPPER TROUGH WILL REMAIN ANCHORED ACROSS THE
GREAT LAKES.  CANNOT FIND MUCH EVIDENCE OF SHORTWAVE FORCING THAT
COULD GENERATE PRECIP. INSTEAD THOUGH...MID-LEVEL HEIGHTS DO NOT
REBOUND MUCH AND CONVECTIVE TEMPERATURES ARE ONLY IN THE UPPER 60S
TO AROUND 70.  THESE TEMPS SHOULD BE BREACHED AROUND MIDDAY SO
THINKING SPOTTY SHOWERS/SPRINKLES IN THE MORNING FROM THE MID DECK
WILL BECOME MORE NUMEROUS LATE MORNING THROUGH EARLY AFTERNOON.  CANNOT RULE
OUT THUNDERSTORMS THAT COULD CONTAIN SMALL HAIL GIVEN THE WET BULB
ZERO HEIGHTS AROUND 9KFT.  HIGHS WILL BE A DEGREE OR TWO WARMER THAN
TODAY.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 235 PM CDT MON JUL 28 2014

TIMING OF PCPN CHCS AGAIN THE MAIN FCST CHALLENGE. THE TWO MAIN
FACTORS MODULATING PCPN CHCS WL BE THE DIURNAL VARIATION IN
STABILITY...AND FORCING FM WK SHRTWVS DROPPING SEWD INTO THE ERN
NOAM LNGWV TROF POSN. PCPN CHCS WL BE MAXIMIXED WITH BOTH FACTORS
ARE IN PHASE. AS OF THIS AFTN...THAT SEEMED MOST LIKLEY TO OCCUR
TUE AND AGAIN THU...WITH WED MORE LIKELY TO HAVE FEWER SHRA. OF
COURSE TIMING OF THE SML SCALE UPR DISTURBANCES IS ALWAYS
DIFFICULT...SO THERE IS NO GUARANTEE THINGS WON/T LOOK DIFFERENT
TOMORROW.

NO SIG CHGS WERE MADE TO THE BROAD-BASED BLEND OF GUIDANCE
PRODUCTS USED TO INITIALIZE THE EXTENDED PART OF THE FCST.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1208 PM CDT MON JUL 28 2014

VFR CONDITIONS EXPECTED TODAY INTO TONIGHT. CLOUDS
AT 5000-6000 FEET AGL WILL BE INCREASING FROM THE NORTH AS A WEAK
UPPER DISTURBANCE DROPS INTO THE NORTHERN GREAT LAKES REGION TODAY
INTO TONIGHT. A FEW SPRINKLES ARE ALSO POSSIBLE ACROSS THE NORTH
THIS AFTERNOON AND EVENING. A BETTER CHANCE OF SHOWERS WILL ARRIVE
TOMORROW BY LATE MORNING BUT THE EXPECTED COVERAGE IS NOT HIGH
ENOUGH TO INCLUDE IN THE TAFS AT THIS POINT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
BEACH HAZARDS STATEMENT UNTIL 6 PM CDT THIS EVENING FOR WIZ050.
&&

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......SKOWRONSKI
AVIATION.......MPC






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