Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 042210
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
410 PM CST WED MAR 4 2015

.SHORT TERM...
251 PM CST

THROUGH THURSDAY NIGHT...

OVERALL...IT LOOKS LIKE A QUITE...BUT UNSEASONABLY COLD SHORT RANGE
PERIOD. THE HEART OF ANOTHER PUSH OF COLD ARCTIC AIR IS EXPECTED TO
SHIFT SOUTH OVER THE AREA TONIGHT INTO THURSDAY AS A POSITIVELY
TILTED UPPER LEVEL TROUGH GRADUALLY SAGS SOUTHWARD. AT THE
SURFACE...HIGH PRESSURE AROUND 1040 MB WILL ALSO BUILD SOUTHEASTWARD
FROM THE NORTHERN PLAINS THIS AFTERNOON...TO CENTRAL ILLINOIS BY
EARLY THURSDAY EVENING.

AS FOR TEMPERATURES TONIGHT...THE CENTER OF THE SURFACE HIGH WILL
REMAIN WEST OF THE AREA...KEEPING THE REGION IN A GRADIENT
SUPPORTING 5 TO 10 KT NORTHWESTERLY FLOW THROUGH THE NIGHT. THIS MAY
HELP TEMPERATURES FROM DROPPING OFF TO MUCH BELOW ZERO ACROSS NORTH
CENTRAL ILLINOIS...WHERE THE COLDEST TEMPERATURES ARE EXPECTED
TONIGHT. FARTHER TO THE SOUTH...THE COMBINATION OF A CONTINUED
NORTHERLY FLOW UP TO 10 KT AND MORE CLOUD COVER TONIGHT SHOULD KEEP
CONDITIONS SEVERAL DEGREES WARMER...ESPECIALLY ACROSS MY EAST CENTRAL
ILLINOIS AND NORTHWESTERN INDIANA COUNTIES. WIND CHILLS TONIGHT LOOK
TO FALL JUST SHY OF CRITERIA ACROSS NORTH CENTRAL ILLINOIS...WHERE
15 TO 20 BELOW ZERO READINGS ARE FORECAST.

ON THURSDAY THE MAIN STORY WILL CONTINUE TO BE THE UNSEASONABLY COLD
CONDITIONS. THE HEART OF THIS COLD AIR MASS...FEATURING AROUND -18
CELSIUS 850 AND 925 MB TEMPERATURES...SHOULD BE CENTERED OVER THE
AREA DURING THE DAY. IT APPEARS THAT A RECORD COLD MAXIMUM
TEMPERATURE COULD BE SET AT KRFD. SEE CLIMO BELOW FOR THE RECORD
INFO. OVERALL...HIGHS ARE ONLY EXPECTED TO REACH INTO THE TEENS
AREA-WIDE...AND THIS WILL SET THE STAGE FOR THE POSSIBILITY FOR
ANOTHER PERIOD OF SUBZERO LOWS IN MANY AREAS THURSDAY NIGHT. THE
CURRENT FORECAST LOW FOR CHICAGO ORD THURSDAY NIGHT IS RIGHT AROUND
+1. THE CURRENT RECORD LOW FOR FRIDAY MORNING IS +2...SO YET
ANOTHER RECORD LOW IS POSSIBLE.

KJB

&&

.LONG TERM...
309 PM CST

FRIDAY THROUGH WEDNESDAY...

AFTER A POSSIBLE RECORD COLD START TO THE DAY...TEMPERATURES
SHOULD BEGIN A NICE WARMING TREND THROUGH THE UPCOMING WEEKEND.
THE SURFACE RIDGE OF HIGH PRESSURE MOVING OVER THE AREA ON
THURSDAY EVENING IS EXPECTED TO SAG SOUTHWARD AND EXPAND ACROSS
MUCH OF THE SOUTHERN HALF OF THE CONUS FRIDAY AND INTO THE
WEEKEND. THIS WILL ALLOW THE DEEP COLD TO SHIFT EASTWARD...AND
ALLOW A MILDER AIR MASS TO GREET THE REGION. CURRENTLY IT APPEARS
TEMPERATURES NEAR 40 ARE POSSIBLE AREA-WIDE FOR SATURDAY AND
SUNDAY...IN SPITE OF A GOOD POSSIBILITY OF A FEW WEAK SYSTEMS AND
SURFACE COLD FRONTS DROPPING ACROSS THE AREA. I HAVE CONTINUED
WITH A DRY FORECAST THROUGH THE WEEKEND...THOUGH THERE IS A VERY
SMALL POTENTIAL OF SOME LIGHT PRECIP FAR NORTH WITH THE PASSAGE
OF EACH WEAK SYSTEM.

EVEN WARMER WEATHER IS LIKELY FOR THE AREA EARLY NEXT WEEK AS THE
LARGE SCALE UPPER LEVEL PATTERN ACROSS THE COUNTRY BECOMES MORE
ZONAL...WITH THE MAIN STORM TRACK SHIFTING WELL NORTH OF THE AREA
OVER SOUTHERN CANADA. THIS SHOULD ALLOW A MUCH WARMER AND DRIER
AIR MASS TO SHIFT EASTWARD OVER MUCH OF THE CENTRAL PORTION OF THE
COUNTRY. THIS WARM-UP COULD EASY PUSH TEMPS UP WELL INTO THE 50S
BY TUESDAY OF NEXT WEEK. THE THREAT FOR PRECIP DURING THIS PERIOD
IS VERY LOW.

KJB

&&

.CLIMATE...

WE COULD COME CLOSE TO A COUPLE RECORDS WITH THIS NEXT COLD SPELL.
THE ONES WITH STARS (*) ARE MOST VULNERABLE.

                  THU 3/5         FRI 3/6
ROCKFORD

RECORD LOW      -9 (1978)        -7 (1960)
RECORD LOW MAX  17 (1960)*

CHICAGO
RECORD LOW 0 (1978)*        2 (1960)*
RECORD LOW MAX   12 (1901)

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* NORTHWEST WINDS OCCASIONALLY GUSTING TO AROUND 20 KT THROUGH SUNSET.

MDB

//DISCUSSION...UPDATED 22Z...

WINDS HAVE SETTLED INTO THE 300-330 DIRECTION AND SHOULD REMAIN IN
THAT RANGE THROUGH THE REST OF THE AFTERNOON. OCCASIONAL GUSTS
AROUND 20 KT WILL DIMINISH THROUGH SUNSET.

MDB

FROM 18Z...

HIGH PRESSURE BUILDING ACROSS THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY WILL RESULT IN VFR CONDITIONS AND BREEZY
NORTHWEST WINDS THROUGH THE TAF PERIOD. PERSISTENT COLD ADVECTION
AND AMPLE SUNSHINE SHOULD ALLOW WINDS AT THE TOP OF THE MIXED
LAYER...ARND 20KT...TO MIX DOWN TO THE SFC. EXPECT THAT GUSTINESS
SHOULD END ARND SUNSET. PREVAILING HIGH PRESSURE WILL KEEP MOSTLY
CLEAR SKIES ACROSS THE AREA THROUGH TOMORROW. AS THE CENTER OF THE
HIGH SETTLES INTO THE OHIO VALLEY TOMORROW...WINDS WILL BACK TO
WLY IN THE AFTERNOON. THE PRESSURE GRADIENT WILL BE RELATIVELY
WEAK...SO WINDS SHOULD BE LESS THAN 10 KT THROUGH THE DAY
TOMORROW.

KREIN

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS.

MDB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...VFR.
FRIDAY THROUGH SUNDAY...MVFR POSSIBLE. SUNDAY...
MONDAY THROUGH TUESDAY...PRIMARILY VFR.

BMD

&&

.MARINE...
214 PM CST

STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS WILL CONTINUE SOUTHEAST
ACROSS THE CENTRAL PLAINS AND INTO THE LOWER OHIO VALLEY BY LATE
THURSDAY. THE HIGH WILL THEN MOVE OFF TO THE EAST FRIDAY AS
LOW PRESSURE MOVES EAST ACROSS SOUTHERN HUDSON BAY. SOUTHERLY WINDS
INCREASE TO AROUND 30 KT AHEAD OF THE LOW. A TRAILING WEAKER
LOW/TROUGH AXIS WILL CLEAR THE LAKE BY SATURDAY MORNING
WHILE STEERING A COLD FRONT ACROSS THE UPPER MIDWEST AND GREAT
LAKES REGION ON SATURDAY AND SHIFTING WINDS TO NORTH/NORTHWESTERLY.
ANOTHER LOW WILL TRACK THROUGH SOUTHERN ONTARIO INTO QUEBEC MONDAY
MORNING.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

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